Hops (Humulus lupulus)

Table of Contents

1. What Hops Are
2. From Brewing Bitter to Bedtime Herb
3. Official Status in Europe and the United States
4. The Active Compounds
5. Sleep: What the Trials Show
6. Stress, Anxiety and Low Mood
7. Hops, 8-Prenylnaringenin and Menopause
8. Xanthohumol: Laboratory Promise, Little Human Data
9. Other Studied Uses
10. Forms and the Doses Used in Studies
11. Safety Findings
12. A Serious Hazard for Dogs
13. Beer Is Not a Hops Supplement
14. The Bottom Line
15. Key Research Papers
16. Connections
17. Featured Videos

What Hops Are

Humulus lupulus is a perennial climbing vine that dies back to its root each winter. The plant is dioecious, meaning each plant is either male or female; only the female plants produce the papery, pale-green cones that brewers and herbalists use.

Tucked at the base of the cone's overlapping bracts are tiny yellow resin glands called lupulin glands. They hold almost everything that matters about hops chemically: the bitter acids that flavour beer, the aromatic essential oil, and the prenylated flavonoids such as xanthohumol. Botanical reviews describe xanthohumol as the principal prenylated flavonoid of the female inflorescences and note that it is made inside these lupulin glands by a specialised branch of the plant's flavonoid chemistry (Stevens and Page, 2004).

In herbal medicine the part used is the dried cone. The European Medicines Agency's herbal committee calls it Lupuli flos, "hop strobile". Botanically, hops belong to the plant family Cannabaceae.

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From Brewing Bitter to Bedtime Herb

The most widespread use of hops has always been in beer. A review of beer and skin health notes that the German beer purity rules, traced to a Bavarian law of 1516, allowed only barley, hops, yeast and water in brewing (Chen and colleagues, 2014). Hops contribute the bitterness and much of the aroma of beer.

Alongside brewing, hop cones entered European herbal practice as a calming, sleep-promoting bitter. That traditional use is the basis of modern regulatory status: the German Commission E, the expert panel that reviewed herbal medicines for German authorities, approved hops for anxiety and mood disorders and restlessness, as a 2017 trial report notes in passing (Kyrou and colleagues, 2017). More recently the European Medicines Agency's Committee on Herbal Medicinal Products adopted a monograph on hop strobile, discussed below.

Hops have also been studied as a supposed aid to breast-milk supply. The U.S. LactMed database describes hops as a purported galactogogue (a substance claimed to increase milk), but reports that a small human study found a hop soup appeared to lower prolactin, the hormone that drives milk production, and that no data exist on hop components in breast milk or on safety in nursing mothers or infants.

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Official Status in Europe and the United States

• European Union. The EMA herbal committee's monograph classifies hop strobile preparations as traditional herbal medicinal products "for relief of mild symptoms of mental stress and to aid sleep". The word traditional matters: the committee states that this status rests on at least 30 years of use, not on clinical-trial proof. It considered the clinical studies but, because they used hops combined with valerian, concluded that firm conclusions on the effects of hops alone could not be drawn. The monograph restricts use to adults and adolescents over 12 and reported no side effects at the time of its assessment. EMA: Lupuli flos
• Germany. Commission E approved hops for anxiety and mood disorders and for restlessness (as cited by Kyrou and colleagues, 2017).
• United States. LactMed reports that hops is "generally recognized as safe" (GRAS) as a food by the Food and Drug Administration. Hop supplements are sold as dietary supplements, which LactMed notes do not require pre-marketing proof of safety or effectiveness.

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The Active Compounds

Hop chemistry is unusually well described, partly because the brewing industry has studied it for more than a century. The main groups are:

• Bitter acids. The alpha acids (humulone and relatives) and beta acids (lupulone and relatives). During brewing the alpha acids are converted to iso-alpha acids, also called isohumulones, which give beer its bitterness.
• 2-methyl-3-buten-2-ol. A small volatile alcohol formed as the alpha acids break down. A 2012 study introduction names it as the compound principally credited with the sedative effect of hop resin, and describes a proposed action through GABA, the brain's main calming chemical messenger (Franco and colleagues, 2012). That mechanism is a hypothesis from earlier work, not something the study itself measured.
• Prenylated flavonoids. Xanthohumol is the main one. In the body it is converted to isoxanthohumol and, in smaller amounts, to 8-prenylnaringenin (8-PN) and 6-prenylnaringenin (Legette and colleagues, 2014). 8-PN has been described in more than one review as the most potent phytoestrogen (plant oestrogen) known (Stevens and Page, 2004; Chen and colleagues, 2014).
• Essential oil and common plant polyphenols such as kaempferol, quercetin and ferulic acid (Chen and colleagues, 2014).

Different products therefore contain very different things. A sleep extract, a beer, a xanthohumol supplement and an 8-PN extract are not interchangeable, and results from one say little about the others.

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Sleep: What the Trials Show

Sleep is the best-studied use, and the main fact to hold onto is that almost every positive human trial tested hops mixed with valerian, and sometimes with other herbs too.

• The largest placebo-controlled trial. In 184 adults with mild insomnia across nine U.S. sleep centres, a valerian–hops tablet taken for 28 days produced modest improvements in sleep measured by diary; few comparisons with placebo reached statistical significance, and sleep measured in the laboratory (polysomnography) showed no significant group differences. Quality of life improved more than with placebo, and there was no rebound insomnia on stopping (Morin and colleagues, 2005).
• A 2025 feasibility trial. Forty people with occasional sleep problems wore sleep trackers; the valerian–hops extract coded Ze 91019 increased tracked sleep by an average of 21.7 minutes a day compared with placebo in exploratory analyses, with no effect on daytime thinking or mood (Schicktanz and colleagues, 2025).
• A three-herb comparison with zolpidem. A valerian, passionflower and hops tablet performed about as well as the prescription sleep drug zolpidem over two weeks in 91 recruited patients; both groups improved and there was no placebo group (Maroo and colleagues, 2013).
• Two negative trials. A fatty-acid supplement with hop extract did no better than olive-oil placebo on sleep quality, melatonin or actigraphy in adults with chronic insomnia (Cornu and colleagues, 2010), and a five-ingredient complex including hops did no better than placebo over two weeks in 171 adults with mild insomnia (Scholey and colleagues, 2017).

Reviews reflect this. A 2010 review found that 12 of 16 studies linked valerian, alone or with hops, to improvements in some sleep measures, but called the studies too different in design for firm conclusions (Salter and Brownie, 2010). A 2021 review concluded that valerian combined with hops and passionflower gave the best results among the plant combinations it examined (Borrás and colleagues, 2021). The details are on Sleep and the Valerian Combination.

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Stress, Anxiety and Low Mood

One small trial tested hops on its own. Thirty-six healthy young adults who reported at least mild depression, anxiety and stress took a hop dry extract (two 0.2 g capsules once daily) or placebo for four weeks each, in random order. Scores on a standard depression, anxiety and stress questionnaire fell significantly more with hops than with placebo; morning cortisol and body weight did not change (Kyrou and colleagues, 2017). It was a pilot study, almost all participants were women (31 of 36), and no larger replication appears among the studies reviewed for this page.

A 2022 review of plants used for anxiety, depression and stress grouped hops with lavender, passionflower, lemon balm and valerian as plants that clinical trials have consistently shown to relieve mild forms of these complaints, while calling for more work on how they act (Kenda and colleagues, 2022). The review abstract does not separate trials of hops alone from trials of combinations.

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Hops, 8-Prenylnaringenin and Menopause

Because 8-PN binds oestrogen receptors so strongly in laboratory tests, hop extracts have been tried for hot flushes. The picture is mixed:

• A 2014 mini-review of herbal options for menopause reported that randomised trials of 8-PN gave conflicting results (Depypere and Comhaire, 2014).
• A 2018 review of 8-PN described the clinical results in menopause as promising, but stressed that long-term safety of phytoestrogens is questioned and that more precise evidence is needed (Štulíková and colleagues, 2018).
• A 2021 review of herbal products for menopause concluded that the available data do not fully support hops for menopausal symptoms, in contrast with black cohosh and red clover (Kenda and colleagues, 2021).
• In animal studies, 8-PN lowered the pituitary hormones LH and FSH, raised prolactin and uterine weight, and thickened the vaginal lining — classic signs of oestrogen action (as summarised by Abdi and colleagues, 2016).

An important practical point comes from a human study of xanthohumol: after single doses of up to 180 mg, 8-PN was undetectable in the blood of most people (Legette and colleagues, 2014). How much 8-PN a person is actually exposed to therefore depends heavily on the product. See 8-Prenylnaringenin and Menopause.

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Xanthohumol: Laboratory Promise, Little Human Data

Xanthohumol attracts more research papers than any other hop compound. A 2021 review describes activity, mostly in cells and animals, against ageing, diabetes, inflammation, microbial infection and cancer (Girisa and colleagues, 2021). The human picture is far thinner:

• A 2022 review of cardiometabolic effects found consistent benefits on body weight, blood fats and glucose in animals, but called the human evidence inconsistent and quantitatively insufficient, while noting that xanthohumol was safe and well tolerated in the human studies that exist (Neumann and colleagues, 2022).
• A single-dose study in 48 adults measured how xanthohumol is absorbed: blood levels peaked around one hour and again at four to five hours, and the half-life was about 18–20 hours at the two higher doses (Legette and colleagues, 2014).
• In a small crossover study, 14 healthy adults drank a beverage with 0.125 mg xanthohumol; their isolated white blood cells then responded less strongly to a bacterial trigger in the laboratory (Jung and colleagues, 2022). That is a laboratory marker, not a health outcome.

The cancer and skin claims seen online rest on cell and animal studies. Details: Xanthohumol Research.

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Other Studied Uses

• Overactive bladder. A 12-week observational study of 117 women used a combination of pumpkin seed oil, fragrant sumac bark and hop cone extract. Urination frequency and leakage fell from baseline (Gauruder-Burmester and colleagues, 2019). There was no placebo group, the study was funded by the product's maker, and hops was one of three ingredients, so the effect of hops cannot be separated out.
• Blood-vessel function. In a randomised crossover study of 23 people (12 smokers, 11 non-smokers), an isomerised hop extract rich in the beer-bitter compounds isohumulones improved flow-mediated dilation, a short-term ultrasound measure of artery lining function, at 30 and 120 minutes (Tomita and colleagues, 2017). This was an acute single-dose effect; no long-term outcomes were studied.
• Skin. Reviews describe xanthohumol and other hop compounds as antibacterial, anti-inflammatory and pigment-reducing in laboratory work, and note that direct clinical evidence is lacking (Chen and colleagues, 2014; Kołodziejczak and colleagues, 2024).

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Forms and the Doses Used in Studies

Hops are sold as dried cones for tea, as liquid and dry extracts, in capsules and tablets (most often combined with valerian), and as isolated xanthohumol or 8-PN-standardised extracts. The amounts below are what particular studies used, not a dosing guide:

• Valerian–hops tablets (Morin and colleagues, 2005): two tablets nightly, together containing 187 mg of native valerian extract and 41.9 mg of native hop extract, for 28 days.
• Hop dry extract alone (Kyrou and colleagues, 2017): two 0.2 g capsules once daily for four weeks.
• Xanthohumol (Legette and colleagues, 2014): single oral doses of 20, 60 or 180 mg in a pharmacokinetic study.
• Xanthohumol in a drink (Jung and colleagues, 2022): 0.125 mg, chosen as an amount achievable through diet.
• Non-alcoholic beer (Franco and colleagues, 2012): 333 ml with 0.0% alcohol with supper for 14 days.

The EMA monograph lists specific preparations and doses for traditional use in adults and adolescents over 12; the committee's documents are linked above.

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Safety Findings

• Side effects in trials were few. No serious adverse events were reported with valerian–hops in the 184-person trial (Morin and colleagues, 2005), and the EMA reported no side effects for hop strobile at the time of its assessment.
• Sedation. LactMed states that hops can cause sedation and advises against its use with other sedating drugs and in people with depression.
• Hormone-like activity. Because of 8-PN, LactMed notes that some sources advise against hops during breastfeeding. Reviews of botanicals for women's health point out that such products have not been rigorously tested for toxic effects or drug interactions (Dietz and colleagues, 2016).
• Possible drug-metabolism effects. In human liver preparations in the laboratory, valerian and valerian–hops extracts inhibited glucuronidation, one of the liver's main routes for clearing drugs and hormones (Alkharfy and Frye, 2007). Whether this matters in people has not been established.
• Allergy to hops is described as rare (LactMed).
• Dogs. Veterinary studies describe hops as dangerous to dogs, causing severe overheating that can be fatal; see below and Dog Poisoning, Allergy and Beer.

Questions about combining any herb with prescription medicines are for a clinician or pharmacist.

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A Serious Hazard for Dogs

Hops are a recognised poisoning hazard in veterinary medicine. In the first published series, five dogs (four of them Greyhounds) ate spent hops from brewing; within about three hours they developed very high body temperature, panting, restlessness, vomiting, abdominal pain and seizures, and four of the five died (Duncan and colleagues, 1997). The authors compared the reaction to malignant hyperthermia, an inherited, runaway muscle-heat reaction.

Larger poison-centre reviews have since been published. Among 71 dogs, hyperthermia occurred in 96% and 77% survived with intensive treatment; each degree of temperature rise was associated with a 78% higher chance of death (Pfaff and colleagues, 2022). Among 177 dogs reported to another poison centre, outcomes were known for 83, and 95.2% of those survived; 8 developed severe hyperthermia above 41.4 °C and 3 of them died (Becker and colleagues, 2023). Hops calls rose as a share of all the centre's cases over the 13 years studied.

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Beer Is Not a Hops Supplement

Human exposure to xanthohumol and 8-PN comes mainly from beer (Stevens and Page, 2004), so it is tempting to read hop research as a case for beer. The research does not support that step. Reviews note that direct clinical evidence for beer compounds is lacking and that how much of these compounds reaches the body from moderate beer drinking, and whether it does any good, still needs study (Chen and colleagues, 2014). Beer also contains alcohol, which brings its own well-documented harms; see Alcohol.

The one study that used beer for sleep used non-alcoholic beer (0.0% alcohol): 17 nurses on rotating or night shifts fell asleep faster on actigraphy (about 12 minutes versus 20.5 minutes) and reported lower anxiety during 14 days of drinking it with supper, compared with their own control period (Franco and colleagues, 2012). There was no placebo drink and no blinding.

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The Bottom Line

• Sleep: modest, mostly subjective benefits in trials of valerian–hops combinations; two trials of other hop-containing mixtures were negative; hops alone untested for sleep in a proper trial.
• Stress and mood: one small positive pilot trial of hops alone in young adults.
• Menopause: a very potent plant oestrogen in lab assays; human trial results conflict; reviews disagree on how promising it is.
• Xanthohumol: broad cell and animal activity; human data limited to absorption and small marker studies.
• Safety: few side effects reported in people; hormone-like activity and sedation are the main open questions; genuinely dangerous to dogs.

The deeper evidence is laid out on the Hops Benefits hub.

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Key Research Papers

1. Morin CM, Koetter U, Bastien C, et al. Valerian-hops combination and diphenhydramine for treating insomnia: a randomized placebo-controlled clinical trial. Sleep. 2005;28(11):1465-71. PubMed PMID: 16335333
2. Schicktanz N, Gerhards C, Schlitt T, et al. Effects of a Valerian-Hops Extract Combination (Ze 91019) on Sleep Duration and Daytime Cognitive and Psychological Parameters in Occasional Insomnia: A Randomized Controlled Feasibility Trial. Brain and behavior. 2025;15(6):e70600. PubMed PMID: 40462685
3. Maroo N, Hazra A, Das T. Efficacy and safety of a polyherbal sedative-hypnotic formulation NSF-3 in primary insomnia in comparison to zolpidem: a randomized controlled trial. Indian journal of pharmacology. 2013;45(1):34-9. PubMed PMID: 23543804
4. Cornu C, Remontet L, Noel-Baron F, et al. A dietary supplement to improve the quality of sleep: a randomized placebo controlled trial. BMC complementary and alternative medicine. 2010;10:29. PubMed PMID: 20569455
5. Scholey A, Benson S, Gibbs A, et al. Exploring the Effect of Lactium™ and Zizyphus Complex on Sleep Quality: A Double-Blind, Randomized Placebo-Controlled Trial. Nutrients. 2017;9(2). PubMed PMID: 28218661
6. Salter S, Brownie S. Treating primary insomnia - the efficacy of valerian and hops. Australian family physician. 2010;39(6):433-7. PubMed PMID: 20628685
7. Borrás S, Martínez-Solís I, Ríos JL. Medicinal Plants for Insomnia Related to Anxiety: An Updated Review. Planta medica. 2021;87(10-11):738-753. PubMed PMID: 34116572
8. Kyrou I, Christou A, Panagiotakos D, et al. Effects of a hops (Humulus lupulus L.) dry extract supplement on self-reported depression, anxiety and stress levels in apparently healthy young adults: a randomized, placebo-controlled, double-blind, crossover pilot study. Hormones (Athens, Greece). 2017;16(2):171-180. PubMed PMID: 28742505
9. Kenda M, Kočevar Glavač N, Nagy M, et al. Medicinal Plants Used for Anxiety, Depression, or Stress Treatment: An Update. Molecules (Basel, Switzerland). 2022;27(18). PubMed PMID: 36144755
10. Franco L, Sánchez C, Bravo R, et al. The sedative effect of non-alcoholic beer in healthy female nurses. PloS one. 2012;7(7):e37290. PubMed PMID: 22815680
11. Štulíková K, Karabín M, Nešpor J, et al. Therapeutic Perspectives of 8-Prenylnaringenin, a Potent Phytoestrogen from Hops. Molecules (Basel, Switzerland). 2018;23(3). PubMed PMID: 29543713
12. Depypere HT, Comhaire FH. Herbal preparations for the menopause: beyond isoflavones and black cohosh. Maturitas. 2014;77(2):191-4. PubMed PMID: 24314619
13. Kenda M, Glavač NK, Nagy M, et al. Herbal Products Used in Menopause and for Gynecological Disorders. Molecules (Basel, Switzerland). 2021;26(24). PubMed PMID: 34946512
14. Stevens JF, Page JE. Xanthohumol and related prenylflavonoids from hops and beer: to your good health! Phytochemistry. 2004;65(10):1317-30. PubMed PMID: 15231405
15. Legette L, Karnpracha C, Reed RL, et al. Human pharmacokinetics of xanthohumol, an antihyperglycemic flavonoid from hops. Molecular nutrition & food research. 2014;58(2):248-55. PubMed PMID: 24038952
16. Neumann HF, Frank J, Venturelli S, et al. Bioavailability and Cardiometabolic Effects of Xanthohumol: Evidence from Animal and Human Studies. Molecular nutrition & food research. 2022;66(6):e2100831. PubMed PMID: 34967501
17. Jung F, Staltner R, Tahir A, et al. Oral intake of xanthohumol attenuates lipoteichoic acid-induced inflammatory response in human PBMCs. European journal of nutrition. 2022;61(8):4155-4166. PubMed PMID: 35857130
18. Gauruder-Burmester A, Heim S, Patz B, et al. Cucurbita pepo-Rhus aromatica-Humulus lupulus Combination Reduces Overactive Bladder Symptoms in Women - A Noninterventional Study. Planta medica. 2019;85(13):1044-1053. PubMed PMID: 31261419
19. Tomita J, Mochizuki S, Fujimoto S, et al. Acute improvement of endothelial functions after oral ingestion of isohumulones, bitter components of beer. Biochemical and biophysical research communications. 2017;484(4):740-745. PubMed PMID: 28131837
20. Chen W, Becker T, Qian F, et al. Beer and beer compounds: physiological effects on skin health. Journal of the European Academy of Dermatology and Venereology : JEADV. 2014;28(2):142-50. PubMed PMID: 23802910
21. Hops. Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006–. PubMed PMID: 30000893
22. Alkharfy KM, Frye RF. Effect of valerian, valerian/hops extracts, and valerenic acid on glucuronidation in vitro. Xenobiotica; the fate of foreign compounds in biological systems. 2007;37(2):113-23. PubMed PMID: 17484515
23. Duncan KL, Hare WR, Buck WB. Malignant hyperthermia-like reaction secondary to ingestion of hops in five dogs. Journal of the American Veterinary Medical Association. 1997;210(1):51-4. PubMed PMID: 8977648
24. Pfaff A, Sobczak BR, Babyak JM, et al. Retrospective analysis of hops toxicosis in dogs (2002-2014): 71 cases. Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001). 2022;32(1):90-97. PubMed PMID: 34498796
25. Becker J, Brutlag AG, Hovda L, et al. A retrospective evaluation of hops ingestion in 177 dogs (2005-2018). Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001). 2023;33(3):348-353. PubMed PMID: 36908194

PubMed Topic Searches

1. PubMed: Hops (Humulus lupulus) sleep and insomnia
2. PubMed: Hops 8-prenylnaringenin and menopause
3. PubMed: Xanthohumol human studies
4. PubMed: Hops toxicosis in dogs

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Connections

• Calming and Hormonal Herbs — the category this herb belongs to
• Hops Benefits Deep Dive — the evidence ledger and all four articles
• Sleep and the Valerian Combination — why hops is rarely tested alone
• 8-Prenylnaringenin and Menopause — the potent hop phytoestrogen
• Xanthohumol Research — lab promise and human data
• Dog Poisoning, Allergy and Beer — the safety findings
• Valerian — the herb hops is almost always paired with
• Passionflower — the third herb in several sleep combinations
• Lemon Balm — another calming herb studied for stress and sleep
• Red Clover — an isoflavone-rich plant studied for menopause
• Black Cohosh — the most-studied herb for hot flushes
• Insomnia — the condition behind most hop research
• Anxiety — the other traditional indication
• Menopause — where 8-prenylnaringenin has been tested
• Alcohol — why beer is a different matter from hops

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