Albendazole

Table of Contents

1. What Albendazole Is
2. Discovery: From Farm Animals to People
3. How It Acts on Worms
4. How the Body Handles It
5. Neurocysticercosis: Tapeworm Cysts in the Brain
6. Hydatid Disease: Tapeworm Cysts in the Liver and Lungs
7. Intestinal Worms: Roundworm, Hookworm, Whipworm, Pinworm
8. Other Infections in the Research
9. Mass Deworming and Lymphatic Filariasis
10. Resistance and Falling Efficacy
11. Cancer Research
12. Safety Findings
13. Pregnancy and Breastfeeding
14. What Is Not Known
15. Connections
16. Key Research Papers
17. Featured Videos

What Albendazole Is

Albendazole is a synthetic, man-made medicine. Chemically it is methyl 5-(propylthio)-2-benzimidazolecarbamate, a white to yellowish powder that, in the words of the United States label, is "practically insoluble in alcohol and in water." It belongs to the benzimidazoles, a family of anthelmintics — medicines that kill parasitic worms (helminths). Its relatives include mebendazole, used in people, and fenbendazole and oxfendazole, used in animals.

In the United States albendazole is sold as 200 milligram tablets that the label says may be crushed or chewed and swallowed with water. The label lists two approved uses, both caused by the larval (immature) stage of a tapeworm:

• Neurocysticercosis — "parenchymal neurocysticercosis due to active lesions caused by larval forms of the pork tapeworm, Taenia solium." These are cysts in the brain tissue itself.
• Hydatid disease — "cystic hydatid disease of the liver, lung, and peritoneum, caused by the larval form of the dog tapeworm, Echinococcus granulosus."

Outside the label, albendazole is one of two medicines the World Health Organization lists for deworming against roundworm, hookworm and whipworm, and part of every World Health Organization drug combination for lymphatic filariasis. Its 2017 deworming guideline notes that the albendazole 400 milligram chewable tablet is on the World Health Organization Model List of Essential Medicines for Children, as an intestinal deworming and an antifilarial medicine.

Human and veterinary products

Albendazole is also an animal medicine: the DailyMed label database of the United States National Library of Medicine lists veterinary albendazole suspensions, separate products from the human tablets.

Discovery: From Farm Animals to People

Albendazole was first described in 1976 in a short scientific report titled "Anthelmintic activity of albendazole against liver flukes, tapeworms, lung and gastrointestinal roundworms" (Theodorides and colleagues, 1976). Its early research was in farm animals. A 1980 study in sheep found that albendazole itself was barely detectable in the blood; what circulated was its breakdown product, albendazole sulfoxide, and the authors concluded that much of the drug's activity "is due to the metabolically formed sulfoxide and sulfone" (Marriner and Bogan, 1980). That finding — the swallowed drug is a delivery form for an active metabolite — still describes how it works in people.

The United States label gives the drug's initial approval in that country as 1996. LiverTox, the liver-safety reference of the United States National Institutes of Health, lists the dates of the benzimidazoles reaching the American market: thiabendazole in 1967, mebendazole in 1974, albendazole in 1996 and triclabendazole in 2019 (Hoofnagle, LiverTox). Much of the early research in people, on neurocysticercosis and hydatid disease, came from Latin America and India.

How It Acts on Worms

The label describes the mechanism this way: albendazole "binds to the colchicine-sensitive site of β-tubulin inhibiting their polymerization into microtubules." Tubulin is the protein cells use to build microtubules — tiny internal tubes that act as scaffolding and transport tracks. With albendazole bound to the worm's tubulin, the tubes cannot form.

According to the label, the loss of microtubules in the worm's intestinal cells reduces their ability to absorb nutrients, "especially the uptake of glucose," and depletes the worm's stored sugar (glycogen). Without enough glucose the parasite cannot make enough energy, "and the parasite eventually dies."

Laboratory work on tapeworm tissue

Tapeworms and flukes have no gut; they absorb food through their skin-like outer layer, the tegument. A 2025 laboratory study of a model tapeworm, Mesocestoides corti, found that the microtubules of this outer layer were "specifically sensitive to low, chemotherapeutically relevant concentrations" of albendazole and albendazole sulfoxide, and that albendazole also caused a broad drop in the worm's protein production (Guarnaschelli and Koziol, 2025). This was laboratory work, not a study in people.

Why the dose matters to the person taking it

A 2021 review describes albendazole and mebendazole as blocking "the microtubule systems of parasites and mammalian cells" (Chai and colleagues, 2021) — that is, human cells are not completely immune to the effect. LiverTox notes that for gut worms "a single dose of a poorly absorbed anthelmintic is usually effective," while systemic infections need longer courses (Hoofnagle, LiverTox). The serious side effects described on the label — bone-marrow suppression and liver injury — are tied mostly to the long courses used for tissue cysts (see Safety Findings).

How the Body Handles It

Pharmacokinetics describes how a drug is absorbed, spread, broken down and removed. The label's findings:

• Absorption is poor. Albendazole "is poorly absorbed from the gastrointestinal tract due to its low aqueous solubility." Albendazole itself is "negligible or undetectable" in blood because the liver converts it to albendazole sulfoxide before it reaches the circulation. The label attributes the drug's effect on worms outside the gut to this sulfoxide.
• A fatty meal raises the level. When albendazole was taken with a fatty meal (about 40 grams of fat), blood levels of albendazole sulfoxide were "up to 5-fold on average" higher than on an empty stomach. The label directs that the tablets be taken with food, and its dosing table for both approved uses specifies "with meals."
• Peak and half-life. Peak blood levels of the sulfoxide came 2 to 5 hours after a dose. The half-life — the time for the blood level to fall by half — ranged from 8 to 12 hours in healthy volunteers and in patients with hydatid disease or neurocysticercosis.
• Where it goes. The sulfoxide is 70% bound to blood proteins and "widely distributed throughout the body"; it has been found in urine, bile, liver, cyst wall, cyst fluid and the fluid around the brain and spinal cord (cerebrospinal fluid). Blood levels were 3 to 10 times higher than in cyst fluid and 2 to 4 times higher than in cerebrospinal fluid.
• How it leaves. Less than 1% of a dose appears in urine as the sulfoxide; the label states that elimination through bile "presumably accounts for a portion." The sulfoxide is further broken down to albendazole sulfone.
• The body speeds its own clearance. After 4 weeks of treatment, sulfoxide levels were about 20% lower than in the first half of treatment, "suggesting that albendazole may induce its own metabolism."
• Blocked bile ducts. In 5 patients with blockage of the bile ducts outside the liver, peak sulfoxide levels doubled, total exposure rose about 7-fold and the half-life lengthened to 31.7 hours.

Wide differences between people

A 2022 systematic review and modelling analysis pooled studies of single doses and described "extensive inter-individual variation" in albendazole sulfoxide levels. Age, existing parasitic infection (particularly echinococcosis) and a fatty meal before the dose were all associated with differences; a fatty meal was associated with greater absorption (Whittaker and colleagues, 2022).

Neurocysticercosis: Tapeworm Cysts in the Brain

Neurocysticercosis happens when a person swallows eggs of the pork tapeworm (passed in the stool of a human tapeworm carrier) and the larvae settle in the brain as fluid-filled cysts. The 2017 guideline of the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH) states that in endemic areas the infection "is linked to approximately 29% of cases of seizures" (White and colleagues, 2018). The site's pages Parasites in the Brain and Neurocysticercosis Treatment cover the disease itself.

What the label states

For neurocysticercosis the label lists 400 milligrams twice daily with meals for people weighing 60 kilograms or more, and 15 milligrams per kilogram of body weight per day in two doses (maximum 800 milligrams a day) for lighter patients, for 8 to 30 days. It states that patients treated for neurocysticercosis receive "appropriate steroid and anticonvulsant therapy as required," because dying cysts provoke inflammation that can cause seizures and raised pressure inside the skull, and that patients be examined for cysts in the retina (the light-sensing layer at the back of the eye) before treatment, since inflammation around a dying cyst there can damage the retina.

What the 2017 guideline recommends

The guideline of the Infectious Diseases Society of America and the American Society of Tropical Medicine and Hygiene ties treatment to the type of disease (White and colleagues, 2018):

• For one or two living cysts in the brain tissue, it recommends albendazole alone for 10–14 days, describing the usual dose as 15 milligrams per kilogram per day in two doses "with food," with a maximum of 1,200 milligrams a day.
• For more than two living cysts, it recommends albendazole combined with praziquantel for 10–14 days rather than albendazole alone.
• For a single enhancing lesion (one cyst that is already degenerating), it suggests albendazole for 1–2 weeks rather than no antiparasitic treatment, and recommends corticosteroids started before it.
• For people with untreated hydrocephalus (fluid build-up in the brain) or diffuse brain swelling, it recommends managing the raised pressure "and not antiparasitic treatment"; its text explains that in these cases antiparasitic drugs "can lead to fatal adverse events, such as herniation."
• For cysts that have already turned into calcium deposits, it recommends symptom treatment alone instead of antiparasitic drugs.
• It recommends an eye examination of the retina before treatment for all patients, and monitoring for liver injury and low white-cell counts in anyone treated with albendazole for more than 14 days.

The trial evidence

A 2021 Cochrane review (a systematic review by the independent Cochrane network) pooled 16 trials; almost all usable data concerned albendazole. For people with a single cyst, albendazole "probably improves seizure recurrence" — fewer seizures came back (risk ratio 0.61; 5 trials, 396 participants, moderate-certainty evidence). Those trials recruited people whose cysts were already non-viable, and most were children. For people with multiple cysts the reviewers were uncertain, and the direction of the very low-certainty evidence pointed towards harm (risk ratio 2.05; 2 trials). Albendazole probably slightly increased the complete clearing of lesions on scans, and side effects — mostly headache, abdominal pain and nausea or vomiting — were more common with treatment (Monk and colleagues, 2021).

Not every trial found a benefit. A 1995 Indian placebo-controlled trial of 29 patients with multiple cysts found no significant difference in cyst reduction at 3 months after 7 days of albendazole, concluding that this regimen "does not change the natural course of neurocysticercosis" (Padma and colleagues, 1995).

A 2014 double-blind trial in Peru randomised 124 patients with living brain cysts. Complete cyst resolution on 6-month brain scans was seen in 64% of those given albendazole plus praziquantel, against 37% given standard-dose albendazole alone; a higher albendazole dose gave 53%, a difference from standard dose that was not statistically significant. Side effects did not differ significantly between groups (Garcia and colleagues, 2014). The label reports that praziquantel raises albendazole sulfoxide levels in the blood by about 50%. The site's page Praziquantel and Albendazole covers the combination in more detail.

Hydatid Disease: Tapeworm Cysts in the Liver and Lungs

Hydatid disease (cystic echinococcosis) is caused by the larval stage of the dog tapeworm Echinococcus granulosus. People swallow eggs passed by infected dogs, and slow-growing cysts form, mostly in the liver and lungs. A related species, Echinococcus multilocularis, causes alveolar echinococcosis, which grows into the liver more like a tumour. The site's Echinococcus page covers the parasite.

What the label states

For hydatid disease the label lists the same weight-based daily dose as for neurocysticercosis, given in cycles: 28 days of treatment followed by a 14-day break, for a total of 3 cycles. Blood counts and liver enzymes are to be checked at the start of each cycle and every 2 weeks during it.

Where albendazole fits beside surgery

Reviews describe surgery as the main treatment and albendazole as a partner to it. A 2025 review of liver echinococcosis calls surgical management "the cornerstone of treatment," describes albendazole, mebendazole and praziquantel as options "for treating small cysts and preventing recurrence after surgery," and states that alveolar echinococcosis, which is usually not operable except early, is managed with albendazole (Pavlidis and colleagues, 2025).

The lungs are different. A 2023 review of lung cysts describes surgery as "the mainstay of treatment" and reports that albendazole "induces decay of the parasitic cyst membrane, opening of cystobronchial fistulas and cyst complications, which can be life threatening" — a breakdown of the cyst wall that can connect the cyst to the airways (Weber and colleagues, 2023).

A 2022 Turkish study looked back at 153 patients given albendazole after surgery for lung cysts. Liver enzymes rose partially in 16 patients (10.5%), one had mild low white-cell counts, one had a recurrence 30 months later, and none had to stop the drug (Aydin and colleagues, 2022). With no comparison group, it describes tolerance, not prevention of recurrence.

Intestinal Worms: Roundworm, Hookworm, Whipworm, Pinworm

The "soil-transmitted helminths" are three worms spread through soil contaminated with human faeces: the large roundworm (Ascaris lumbricoides), hookworms and whipworm (Trichuris trichiura). For these, albendazole is given as a single dose; the World Health Organization's fact sheet lists albendazole 400 milligrams and mebendazole 500 milligrams as its recommended medicines.

Roundworm

A 2020 Cochrane review of 30 trials with 6,442 participants found that single doses of albendazole, mebendazole or ivermectin all cured most infections, with an illustrative cure rate of 93% against 16% with placebo. A single dose of albendazole was as effective as several doses (high-certainty evidence), and the review detected no difference between albendazole and mebendazole or ivermectin. No included trial reported a serious adverse event (Conterno and colleagues, 2020). See Albendazole and Mebendazole for Roundworm.

Hookworm and whipworm

A 2017 network meta-analysis (a statistical method that compares several drugs across many trials at once) of single-dose regimens found that all four standard drugs worked well against roundworm. Albendazole had the highest cure rate against hookworm, 79.5%. Against whipworm all drugs did poorly; mebendazole had the highest cure rate, 42.1% (Moser and colleagues, 2017).

Pairing albendazole with ivermectin raised whipworm cure rates in trials in Laos and on Pemba Island, Tanzania. Six months after treatment, cure rates were 65.8% with the combination against 13.4% with albendazole alone in Laos, and 17.8% against 1.4% on Pemba (Keller and colleagues, 2021).

A growth question from 1998

A 1998 trial in 622 Mexican children with symptom-free whipworm compared a 3-day albendazole course, one albendazole dose and pyrantel. In lightly infected children, weight gain and arm measures were smaller with the 3-day course than with pyrantel. The authors wrote that "possible toxic effects of high-dose albendazole require further investigation" (Forrester and colleagues, 1998).

Albendazole is also used against pinworm (Enterobius vermicularis), the common threadworm of children (Cañete and colleagues, 2012); see Pyrantel and Albendazole for Pinworm.

Other Infections in the Research

A 2021 review lists many other worm infections against which albendazole and mebendazole have shown "considerable therapeutic effects," including the wandering-larva infections called visceral, ocular, neural and cutaneous larva migrans, trichinosis, angiostrongyliasis and gnathostomiasis, and it notes that albendazole has been tried against several protozoa (single-celled parasites) such as Giardia (Chai and colleagues, 2021). These uses lie outside the United States label.

Toxocara and larva migrans

Toxocara roundworms of dogs and cats can migrate through human organs (visceral and ocular larva migrans), and larvae of animal hookworms can wander under the skin, leaving itchy, snaking tracks (cutaneous larva migrans). The 2021 review lists all of these among the infections where benzimidazoles have shown therapeutic effects (Chai and colleagues, 2021). The site covers Toxocara treatment in Albendazole for Toxocara.

Trichinella

Trichinosis comes from eating undercooked meat containing Trichinella larvae, which settle in muscle. The 2021 review lists it among the tissue infections treated with benzimidazoles (Chai and colleagues, 2021); the site's Albendazole and Mebendazole for Trichinella page covers the evidence.

Giardia

A 2012 double-blind trial in Cuba randomised 150 adults with symptomatic Giardia infection to albendazole 400 milligrams daily or metronidazole 250 milligrams three times daily, each for 5 days. Cure rates were similar, 82.6% and 85.3%. Bitter taste, headache, vomiting and dizziness were more common with metronidazole; abdominal pain was more common with albendazole (Cañete and colleagues, 2012). The site's Refractory Giardiasis and Drug Resistance page covers infections that do not clear.

Strongyloides

The threadworm Strongyloides stercoralis is the exception among intestinal worms. The World Health Organization's fact sheet states that this parasite "is not sensitive to albendazole or mebendazole" and so is not affected by mass deworming; ivermectin is the drug used against it (see the site's Strongyloides page).

Mass Deworming and Lymphatic Filariasis

Mass drug administration means giving a medicine to everyone in a target group — all schoolchildren, or a whole community — without testing each person first.

The 2017 World Health Organization deworming guideline

The World Health Organization's 2017 guideline on preventive chemotherapy (deworming) recommends deworming with a single dose of albendazole 400 milligrams or mebendazole 500 milligrams, given once or twice a year, for young children aged 12–23 months, preschool and school-age children, and for non-pregnant adolescent girls and women of reproductive age, in areas where 20% or more of that group carry any soil-transmitted worm; twice-yearly treatment is recommended where the figure is over 50%. A half dose of albendazole, 200 milligrams, is recommended for children younger than 24 months. A separate, conditional recommendation covers pregnant women after the first trimester (see Pregnancy and Breastfeeding). The World Health Organization's fact sheet describes the two medicines as "effective, inexpensive and easy to administer by non-medical personnel (e.g. teachers)," and states that both are donated to ministries of health through the World Health Organization in all endemic countries for the treatment of school-age children.

What the evidence shows about mass deworming

The research is split on what mass deworming achieves beyond removing worms. A 2019 Cochrane review of 51 trials concluded that public health programmes that regularly treat all children "do not appear to improve height, haemoglobin, cognition, school performance, or mortality," that it is not known whether school attendance improves, and that large weight gains reported in some older trials were not found in more recent ones (Taylor-Robinson and colleagues, 2019). The site's Mass Deworming Programs and Hookworm Mass Drug Administration and Control pages go further.

Lymphatic filariasis

Lymphatic filariasis (the cause of elephantiasis) is caused by thread-like worms such as Wuchereria bancrofti, spread by mosquitoes; the larvae circulating in the blood are called microfilariae. The World Health Organization's fact sheet lists four regimens: albendazole 400 milligrams alone twice a year where the eye worm Loa loa is also present; ivermectin with albendazole where river blindness occurs; diethylcarbamazine with albendazole where it does not; and all three together (ivermectin, diethylcarbamazine and albendazole) where river blindness is absent and "other programmatic conditions are met."

The three-drug regimen rests on a 2018 trial in Papua New Guinea. In 182 adults with microfilariae in the blood, a single dose of all three drugs cleared them in 96% of participants at 12, 24 and 36 months. A single dose of diethylcarbamazine plus albendazole cleared 32% at 12 months and 83% at 36 months; the two-drug pair given once a year for 3 years cleared 98% at 36 months. Moderate adverse events were more common with three drugs (27% against 5%), and there were no serious adverse events (King and colleagues, 2018).

A larger community trial in Papua New Guinea compared the two regimens in 4,563 people. Adverse events, 87% of them mild, were similar overall (18% with two drugs, 20% with three), with none serious; they were more frequent in people with microfilariae in the blood. Microfilariae cleared in 96% with three drugs and 84% with two (Tavul and colleagues, 2022). See the site's Lymphatic Filariasis page.

Resistance and Falling Efficacy

The label describes the known mechanism of resistance: "changes in amino acids that result in changes in the β-tubulin protein," reducing how well the drug binds. In farm animals, benzimidazole resistance is widespread; in people, the evidence is of falling efficacy rather than proven resistance in most worms.

The clearest signal concerns whipworm. The 2017 network meta-analysis estimated that between 1995 and 2015 the cure rate of albendazole against whipworm fell from 38.6% to 16.4%, and the egg-reduction rate from 72.6% to 43.4%, both statistically significant. The authors called the decrease "of concern" and called for new drugs (Moser and colleagues, 2017). The 2021 review lists hookworm, whipworm, possibly roundworm, Wuchereria bancrofti and Giardia as organisms with "emerging issues of drug resistance" (Chai and colleagues, 2021).

Laboratory genetics is mapping the mechanism. In the model roundworm Caenorhabditis elegans, a 2024 study found that losing one β-tubulin gene, ben-1, gave the maximum level of resistance to albendazole, and losing a second β-tubulin gene did not add to it; the authors note that variants in ben-1 alone do not explain the differences in benzimidazole response across parasite populations (Collins and colleagues, 2024). This is laboratory work on a free-living worm.

Cancer Research

Because albendazole disrupts microtubules — structures several cancer drugs also target — it has been studied as a possible cancer drug. It is not approved for any cancer, and no study reviewed here shows it cures cancer.

• Cell and animal studies. A 2021 review reports that albendazole and mebendazole have been active "in vitro and in vivo (animals)" against liver, lung, ovary, prostate, colorectal, breast, and head and neck cancers and melanoma (Chai and colleagues, 2021). These are laboratory and animal results, not results in patients.
• One dose-finding trial in people. A phase 1 trial (a small first-in-patient study of safety and dose) gave oral albendazole to 36 people with advanced solid tumours that had stopped responding to treatment. The highest tolerated dose was 2,400 milligrams a day (1,200 milligrams twice daily), and bone-marrow suppression was the main dose-limiting toxicity; 16% of assessable patients had a fall of at least half in a tumour blood marker (Pourgholami and colleagues, 2010). A phase 1 trial is not designed to show that a drug works.
• Why mebendazole is studied more. The 2021 review states that because of albendazole's toxicity at high doses over long periods, "for example, neutropenia due to myelosuppression" (low white cells from bone-marrow suppression), mebendazole "is currently more popularly used than albendazole in anti-cancer clinical trials" (Chai and colleagues, 2021).

The site's page Mebendazole, Fenbendazole and Albendazole in Cancer Research covers this family in more depth.

Safety Findings

Single doses for gut worms

The World Health Organization's 2017 guideline summarises a safety review of benzimidazoles: in drug-safety trials covering more than 6,500 doses of albendazole and mebendazole there were no severe adverse events, and all adverse effects (9.7% for albendazole) "were minor and transient," lasting less than 48 hours. The 2020 Cochrane review of roundworm treatment found no serious adverse events in its trials; the commonest reported effects were nausea, vomiting, abdominal pain, diarrhoea, headache and fever (Conterno and colleagues, 2020).

Long courses: the label's warnings

The label's warnings concern the long courses used for tissue cysts:

• Bone-marrow suppression. "Fatalities associated with the use of" albendazole "have been reported due to granulocytopenia or pancytopenia" (loss of white cells, or of all blood cell types). The label also lists aplastic anaemia and agranulocytosis, calls for blood counts at the start of each 28-day cycle and every 2 weeks, and states that people with liver disease or with echinococcosis in the liver are at higher risk.
• Liver. In clinical trials, mild to moderate liver-enzyme rises occurred in about 16% of patients and generally returned to normal after stopping. The label also reports "case reports of acute liver failure of uncertain causality and hepatitis," and calls for liver tests before each cycle and at least every 2 weeks.
• Brain and eye. People treated for neurocysticercosis may have seizures, raised pressure inside the skull or other neurological symptoms as cysts die; cysts in the retina can be damaged by the inflammation. The label also warns that hidden neurocysticercosis can be "uncovered" in people treated for other conditions.
• Contraindication. Known allergy to the benzimidazole family or to any tablet ingredient.

In the label's trials, reactions in hydatid disease included abnormal liver tests (16%), abdominal pain (6%) and reversible hair loss (2%); in neurocysticercosis, headache (11%) and nausea and vomiting (6% each). Reports after approval include Stevens–Johnson syndrome (a severe skin reaction), rhabdomyolysis (muscle breakdown), acute kidney failure, convulsions and blurred vision; the label notes that such voluntary reports cannot establish frequency or cause.

Liver injury in the literature

A 2021 systematic review collected 12 cases of albendazole-associated liver injury, including two new ones. Most patients had jaundice, loss of appetite and vomiting, after either a single use or long-term use; all had high liver enzymes and recovered after stopping the drug. The authors wrote that it "may induce liver injury, even in small doses" (Piloiu and Dumitrascu, 2021). LiverTox describes albendazole and mebendazole as linked to "rare instances" of liver injury "which can be severe and prolonged" (Hoofnagle, LiverTox).

Interactions reported on the label

Dexamethasone (a corticosteroid often given for neurocysticercosis) raised trough albendazole sulfoxide levels about 56%; praziquantel raised them about 50%; cimetidine (a stomach-acid reducer) about doubled levels in bile and cyst fluid. Because albendazole induces a liver enzyme (cytochrome P450 1A) in human liver-cancer cells in the laboratory, the label recommends monitoring levels of theophylline (an asthma drug) during and after treatment.

Pregnancy and Breastfeeding

What the label states

The label states that, based on animal studies, albendazole "may cause fetal harm when administered to a pregnant woman." In rats and rabbits treated during organ formation, it caused embryo toxicity and skeletal malformations at doses about 0.1 to 0.6 times the human dose (scaled to body surface area); no malformations were seen in mice at the doses tested. In people, the label reports that "a small number of published case series and reports" of multiple-dose use in the first trimester, and "several published studies" of single-dose use later in pregnancy, "have not identified any drug-associated risks for major birth defects, miscarriage, or adverse maternal or fetal outcomes." The label calls for a pregnancy test before treatment in women who could become pregnant, and for effective contraception during treatment and for 3 days after the last dose.

What the World Health Organization states

The World Health Organization's 2017 guideline makes a conditional recommendation of single-dose albendazole 400 milligrams or mebendazole 500 milligrams for pregnant women after the first trimester, in areas where at least 20% of pregnant women carry hookworm or whipworm and anaemia affects 40% or more of them. It reports that, from the limited data on women treated unintentionally in the first trimester, "there appears to be no increased risk of congenital anomalies," but that "because of this uncertainty during the first trimester, deworming medicines are not prescribed during this period." In the trials it reviewed, a single dose in the second trimester lowered worm burden, while anaemia in the third trimester, low birth weight and deaths around the time of birth did not differ from placebo or no treatment.

Breastfeeding

The label reports that albendazole and albendazole sulfoxide levels in human breast milk "have been reported to be low," and that there are "no reports of adverse effects on the breastfed infant."

What Is Not Known

• Multiple brain cysts. The 2021 Cochrane review was uncertain whether albendazole reduces seizure recurrence in people with several cysts; the very low-certainty evidence leaned towards harm (Monk and colleagues, 2021).
• Hydatid disease. A 2019 literature review states that the efficacy of albendazole for hydatid cysts "has not been well documented," while concluding that it "may be associated with the prevention of recurrence and reduction of the size" of cysts (Dehkordi and colleagues, 2019).
• Benefits of mass deworming beyond worm counts. Large reviews disagree on what regular deworming of all children achieves for growth, school attendance and learning (Taylor-Robinson and colleagues, 2019).
• Whipworm and resistance. Whether the fall in albendazole's whipworm efficacy reflects genetic resistance, changes in study methods or something else is not settled (Moser and colleagues, 2017).
• First-trimester safety. Human data are limited to small case series and inadvertent exposures; the animal findings remain the basis of the label's warning.
• Why levels vary between people. Understanding of the factors remains "incomplete" (Whittaker and colleagues, 2022).
• Cancer. There is a single phase 1 dose-finding trial and no controlled trial of albendazole as a cancer treatment in the sources reviewed for this page.

Connections

• All Drugs
• Mebendazole — its closest human relative
• Praziquantel — its partner for brain cysts
• Ivermectin — its partner for filariasis and whipworm
• Fenbendazole — a veterinary benzimidazole
• Parasites — all parasite pages
• Tapeworm — pork and beef tapeworms
• Neurocysticercosis Treatment
• Praziquantel and Albendazole
• Parasites in the Brain
• Echinococcus — hydatid disease
• Ascaris — the large roundworm
• Albendazole and Mebendazole for Roundworm
• Mass Deworming Programs
• Hookworm
• Hookworm Mass Drug Administration
• Whipworm — where efficacy is lowest
• Pyrantel and Albendazole for Pinworm
• Albendazole for Toxocara
• Albendazole and Mebendazole for Trichinella
• Giardia
• Refractory Giardiasis
• Lymphatic Filariasis — the triple-drug regimen
• Strongyloides — the worm it does not reach well
• Benzimidazoles in Cancer Research

Key Research Papers

1. Theodorides VJ, Gyurik RJ, Kingsbury WD, et al. Anthelmintic activity of albendazole against liver flukes, tapeworms, lung and gastrointestinal roundworms. Experientia. 1976;32(6):702-3. PubMed PMID: 950011
2. Marriner SE, Bogan JA. Pharmacokinetics of albendazole in sheep. American Journal of Veterinary Research. 1980;41(7):1126-9. PubMed PMID: 7436109
3. Hoofnagle JH. Anthelmintic Agents. In: LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. 2012-. PubMed PMID: 31643915
4. Guarnaschelli I, Koziol U. Albendazole specifically disrupts microtubules and protein turnover in the tegument of the cestode Mesocestoides corti. PLoS Pathogens. 2025;21(6):e1013221. PubMed PMID: 40465816
5. Chai JY, Jung BK, Hong SJ. Albendazole and Mebendazole as Anti-Parasitic and Anti-Cancer Agents: an Update. The Korean Journal of Parasitology. 2021;59(3):189-225. PubMed PMID: 34218593
6. Whittaker C, Chesnais CB, Pion SDS, et al. Factors associated with variation in single-dose albendazole pharmacokinetics: A systematic review and modelling analysis. PLoS Neglected Tropical Diseases. 2022;16(10):e0010497. PubMed PMID: 36306320
7. White AC Jr, Coyle CM, Rajshekhar V, et al. Diagnosis and Treatment of Neurocysticercosis: 2017 Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA) and the American Society of Tropical Medicine and Hygiene (ASTMH). The American Journal of Tropical Medicine and Hygiene. 2018;98(4):945-966. PubMed PMID: 29644966
8. Monk EJM, Abba K, Ranganathan LN. Anthelmintics for people with neurocysticercosis. The Cochrane Database of Systematic Reviews. 2021;6(6):CD000215. PubMed PMID: 34060667
9. Padma MV, Behari M, Misra NK, et al. Albendazole in neurocysticercosis. The National Medical Journal of India. 1995;8(6):255-8. PubMed PMID: 8520442
10. Garcia HH, Gonzales I, Lescano AG, et al. Efficacy of combined antiparasitic therapy with praziquantel and albendazole for neurocysticercosis: a double-blind, randomised controlled trial. The Lancet Infectious Diseases. 2014;14(8):687-695. PubMed PMID: 24999157
11. Pavlidis ET, Galanis IN, Pavlidis TE. Current considerations for the management of liver echinococcosis. World Journal of Gastroenterology. 2025;31(10):103973. PubMed PMID: 40093668
12. Weber TF, Junghanss T, Stojković M. Pulmonary cystic echinococcosis. Current Opinion in Infectious Diseases. 2023;36(5):318-325. PubMed PMID: 37578473
13. Dehkordi AB, Sanei B, Yousefi M, et al. Albendazole and Treatment of Hydatid Cyst: Review of the Literature. Infectious Disorders Drug Targets. 2019;19(2):101-104. PubMed PMID: 29956639
14. Aydin Y, Ulas AB, Ince I, et al. Evaluation of albendazole efficiency and complications in patients with pulmonary hydatid cyst. Interactive Cardiovascular and Thoracic Surgery. 2022;34(2):245-249. PubMed PMID: 34587626
15. Conterno LO, Turchi MD, Corrêa I, et al. Anthelmintic drugs for treating ascariasis. The Cochrane Database of Systematic Reviews. 2020;4(4):CD010599. PubMed PMID: 32289194
16. Moser W, Schindler C, Keiser J. Efficacy of recommended drugs against soil transmitted helminths: systematic review and network meta-analysis. BMJ. 2017;358:j4307. PubMed PMID: 28947636
17. Keller L, Welsche S, Patel C, et al. Long-term outcomes of ivermectin-albendazole versus albendazole alone against soil-transmitted helminths: Results from randomized controlled trials in Lao PDR and Pemba Island, Tanzania. PLoS Neglected Tropical Diseases. 2021;15(6):e0009561. PubMed PMID: 34191812
18. Forrester JE, Bailar JC 3rd, Esrey SA, et al. Randomised trial of albendazole and pyrantel in symptomless trichuriasis in children. Lancet. 1998;352(9134):1103-8. PubMed PMID: 9798586
19. Cañete R, Rodríguez P, Mesa L, et al. Albendazole versus metronidazole in the treatment of adult giardiasis: a randomized, double-blind, clinical trial. Current Medical Research and Opinion. 2012;28(1):149-54. PubMed PMID: 22114904
20. Taylor-Robinson DC, Maayan N, Donegan S, et al. Public health deworming programmes for soil-transmitted helminths in children living in endemic areas. The Cochrane Database of Systematic Reviews. 2019;9(9):CD000371. PubMed PMID: 31508807
21. King CL, Suamani J, Sanuku N, et al. A Trial of a Triple-Drug Treatment for Lymphatic Filariasis. The New England Journal of Medicine. 2018;379(19):1801-1810. PubMed PMID: 30403937
22. Tavul L, Laman M, Howard C, et al. Safety and efficacy of mass drug administration with a single-dose triple-drug regimen of albendazole + diethylcarbamazine + ivermectin for lymphatic filariasis in Papua New Guinea: An open-label, cluster-randomised trial. PLoS Neglected Tropical Diseases. 2022;16(2):e0010096. PubMed PMID: 35139070
23. Collins JB, Stone SA, Koury EJ, et al. Quantitative tests of albendazole resistance in Caenorhabditis elegans beta-tubulin mutants. International Journal for Parasitology. Drugs and Drug Resistance. 2024;25:100556. PubMed PMID: 38991432
24. Pourgholami MH, Szwajcer M, Chin M, et al. Phase I clinical trial to determine maximum tolerated dose of oral albendazole in patients with advanced cancer. Cancer Chemotherapy and Pharmacology. 2010;65(3):597-605. PubMed PMID: 19904538
25. Piloiu C, Dumitrascu DL. Albendazole-Induced Liver Injury. American Journal of Therapeutics. 2021;28(3):e335-e340. PubMed PMID: 33590990

PubMed Topic Searches

1. PubMed: albendazole neurocysticercosis trials
2. PubMed: mass deworming with albendazole
3. PubMed: triple-drug therapy for lymphatic filariasis
4. PubMed: albendazole and cancer

Other Sources

1. United States label, albendazole tablets 200 milligrams (generic), revised 2026. DailyMed. dailymed.nlm.nih.gov
2. World Health Organization. Guideline: preventive chemotherapy to control soil-transmitted helminth infections in at-risk population groups. Geneva, 2017. who.int
3. World Health Organization, fact sheet: soil-transmitted helminth infections. who.int
4. World Health Organization, fact sheet: lymphatic filariasis. who.int

Featured Videos