Symptoms
Digestive
Liver, Bile & Pancreas
Musculoskeletal
Cardiopulmonary
Neurologic & Cognitive
Constitutional (Whole-Body)
Skin, Hair & Allergic
Urinary
Ear, Nose & Throat
Vascular & Circulatory
Symptoms are the body's signals that something has changed. They point clinicians toward an underlying diagnosis but are rarely a diagnosis on their own — fatigue can mean iron-deficiency anemia, hypothyroidism, depression, sleep apnea, or any of a dozen other conditions, and the same is true of headache, bloating, joint pain, and most of the symptoms above. Each page describes a symptom, its common causes, when it warrants medical evaluation, and links to the conditions where it most often appears. The Symptom-to-Condition Reference Table links each symptom directly to the conditions that produce it.
Detailed pages exist for the symptoms above. The reference table further down covers a wider range, including symptoms without their own dedicated page yet.
Red Flags — Warning Signs by Urgency
Most symptoms can be evaluated by a primary-care physician within a few days. A handful warrant urgent care or emergency care today. The lists below describe the signs that hospitals and clinics treat as emergencies, as same-day problems, or as reasons for a check within a week.
Signs Treated as Emergencies (911)
- Crushing, squeezing, or pressure-like chest pain — especially with shortness of breath, sweating, nausea, or pain radiating to the jaw, neck, or left arm.
- Sudden severe headache (the worst of your life), or sudden weakness or numbness on one side of the body, slurred speech, vision loss, or facial droop.
- Severe difficulty breathing, blue lips or fingertips, or inability to speak in full sentences.
- Vomiting blood, or stool that is black and tarry, maroon, or bright red.
- Severe abdominal pain that is constant and worsening, especially with a rigid abdomen, fever, or vomiting blood.
- Loss of consciousness, a new seizure, or confusion that comes on suddenly.
- Suicidal thoughts with a plan or means.
- New-onset jaundice in someone who looks unwell, or jaundice with fever and right-upper-quadrant pain (suggests cholangitis).
- Rapid swelling of the face, lips, or tongue, or difficulty swallowing or breathing after a food, drug, or insect-sting exposure.
Signs Usually Seen the Same Day
- Fever above 103°F (39.4°C) in an adult, or any fever in someone who is immunocompromised, pregnant, or very elderly.
- New rash that is rapidly spreading, painful, or accompanied by fever.
- Persistent vomiting that prevents keeping any fluids down for more than several hours.
- Moderate, sustained abdominal pain that does not resolve over a few hours.
- Tea- or cola-colored urine in a person who is dehydrated, has just exercised heavily, or has new back pain (rule out rhabdomyolysis or hemolysis).
- New shortness of breath that is not severe but is unfamiliar, particularly in someone with heart or lung disease.
- Heart palpitations that are sustained, accompanied by chest discomfort, lightheadedness, or near-fainting.
Signs Usually Checked Within a Week
- Fatigue that has lasted more than two weeks despite adequate sleep.
- Unintentional weight loss of more than 5 percent of body weight over six months.
- A chronic headache pattern that is changing in frequency or character.
- Persistent joint pain that is interfering with daily activities or work.
- Bloating, reflux, or bowel-habit changes that have lasted more than a few weeks.
- Mild persistent yellowing of the skin or eyes.
- Brain fog, memory complaints, or word-finding difficulty interfering with function.
Symptom-to-Condition Reference Table
A quick map from symptom to the conditions on this site that most often produce it. Where a symptom has its own page, the symptom name is linked. Otherwise, follow the links in the right-hand column to the relevant condition pages.
How These Pages Are Organized
Each symptom page is meant for two readers:
- Someone trying to make sense of a new or persistent symptom. The Overview, Common Causes, and When to Seek Medical Care sections are the starting point — they describe what the symptom usually means, what tests a clinician might order, and when to escalate care.
- Someone trying to understand a symptom that comes with an existing diagnosis. The Mechanisms, Evaluation, and Connections sections explain how the symptom fits the broader condition and what overlapping diagnoses to consider.
None of this content replaces medical care. Every page links to peer-reviewed research with DOIs and to PubMed topic searches so you can read further or bring evidence to your appointments.
Connections
- All Conditions
- By specialty: Cardiology · Dermatology · Endocrinology · ENT · Gastroenterology · Hematology · Infectious Disease · Nephrology & Hepatology · Neurology · Oncology · Ophthalmology · Orthopedics · Pain & Allergy · Psychiatry · Pulmonology · Reproductive Medicine · Rheumatology · Urology
- Lab Tests — the panels most commonly ordered for the symptoms above.
- Bacteria — pathogens behind infectious causes of fever, fatigue, and gastrointestinal (GI) symptoms.
- Toxins — environmental and chemical exposures that present as fatigue, neuropathy, or organ-specific symptoms.
- Vitamins and Minerals — nutrient deficiencies that mimic chronic disease.
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