In-depth

Acute coronary syndrome

Acute coronary syndrome occurs when there isn't enough blood flowing through your heart. It can be felt as chest pain (angina) or a heart attack.

Acute kidney failure

Acute liver failure

Addison's disease

Addison's disease occurs when your adrenal glands produce insufficient amounts of certain important hormones. Treatment may include taking corticosteroids.

Agoraphobia

Do you feel trapped in your own home? Do you worry about having a panic attack? Find out how agoraphobia can be treated.

Airplane ear

Airplane ear, a problem with air pressure in the middle ear, can cause pain and muffled hearing. It can usually be treated with self-care techniques.

Alcohol intolerance

Alcohol poisoning

Alcohol use disorder

Alcoholic hepatitis

Alcohol can severely damage your liver — even moderate drinkers aren't immune. Learn more about this serious liver disease.

Allergies

Amniotic fluid embolism

Amniotic fluid embolism — Overview covers definition, symptoms and treatment of this pregnancy or post-pregnancy condition.

Anaphylaxis

Anaphylaxis is the most serious type of allergic reaction. It often occurs rapidly after exposure to an allergen and may be life-threatening.

Angina

Anthrax

Antibiotic-associated diarrhea

Antibiotics save lives, but they can also have side effects. The most common are mild to severe diarrhea and a serious type of colitis.

Appendicitis

Ascariasis

Autoimmune hepatitis

Autoimmune hepatitis — Early detection, medications can help.

Bee stings

Bee stings — Comprehensive overview covers prevention, treatment of bee stings.

Benign paroxysmal positional vertigo (BPPV)

Bile reflux

Bird flu (avian influenza)

Blastocystis hominis infection

A microscopic parasite causes Blastocystis hominis infection. Experts disagree as to whether this infection causes diarrhea and other associated signs and symptoms.

Blind loop syndrome

Botulism

Brain aneurysm

C. difficile

C. difficile can be a life-threatening infection. It typically develops when antibiotics destroy other bacteria in your intestines, allowing C. difficile to flourish.

Carbon monoxide poisoning

Carcinoid tumors

Carcinoid tumors are rare, slow-growing cancerous tumors that most often occur in the gastrointestinal tract or in the lungs.

Cardiogenic shock

Castleman disease

Celiac disease

Celiac disease is an immune reaction to gluten, a protein found in certain foods. As a result, the body is unable to absorb some important nutrients.

Chagas disease

Chest pain

Cholecystitis

Cholera

Cholera causes severe diarrhea and can kill in a matter of hours, yet can be easily treated with oral or intravenous fluids.

Chronic daily headaches

Chronic kidney disease

Chronic kidney disease, often caused by diabetes or high blood pressure, is the gradual loss of kidney function. Early detection and treatment can help.

Chronic sinusitis

Chronic sinusitis involves long-term inflammation or infection of the sinus cavities. Medications can help, and in rare cases surgery can treat this painful condition.

Churg-Strauss syndrome

Churg-Strauss syndrome is a rare disorder marked by blood vessel inflammation that affects organs throughout the body. Asthma is the most common sign.

Cirrhosis

Colon polyps

Concussion

Concussions can be serious injuries that need sufficient time to heal.

Congenital adrenal hyperplasia

Congenital adrenal hyperplasia is a genetic condition affecting the adrenal glands and interfering with normal growth and development in boys and girls.

Constipation in children

Constipation in children is common. Often, simple changes in diet and routine are helpful.

Cryptosporidium infection

Cryptosporidium infection may cause diarrhea in healthy people, but for people with HIV/AIDS and weakened immune systems, the illness can cause serious complications.

Cyclic vomiting syndrome

Cyclic vomiting syndrome can last for hours or days and shares many triggers with migraines.

Cyclospora infection

Dengue fever

Diabetes insipidus

Diabetes insipidus is a rare condition characterized by intense thirst and the excretion of large amounts of urine.

Diabetic coma

Diabetic ketoacidosis

Diabetic neuropathy

Diverticulitis

Drug allergy

Dumping syndrome

Dysphagia

E. coli

Ear infection (middle ear)

Ear infections are common in children. These bacterial or viral infections of the middle ear can cause mild to severe ear pain.

Ebola virus and Marburg virus

Ectopic pregnancy

Egg allergy

Ehrlichiosis

Encephalitis

Encephalitis is inflammation of the brain usually caused by a viral infection. Severe cases can cause brain damage, even death.

Endometriosis

Endometriosis is a common and often painful disorder in which tissue that normally lines the inside of your uterus grows outside your uterus.

Enlarged liver

You can get an enlarged liver from a number of medical problems or personal habits. Treatment depends on what's causing the enlargement.

Eosinophilic esophagitis

Esophagitis

Exercise headaches

Food allergy

Food allergy symptoms can make you miserable. Unfortunately, there's no cure — but there are steps you can take to keep your symptoms in check.

Food poisoning

Food poisoning has many forms, and some can be serious. Here's how to recognize food poisoning and ways to prevent getting sick.

Gallbladder cancer

Gastritis

Gastroparesis

Giardiasis

Giardia infection is a common waterborne illness. Learn the symptoms and reduce your risk.

Glaucoma

Glaucoma is a group of eye conditions that, left untreated, can seriously damage your optic nerve and lead to blindness.

H. pylori infection

Hangovers

Hantavirus pulmonary syndrome

Hantavirus pulmonary syndrome is initiated by a rodent-carried virus that infects the lung tissues, bringing on flu-like symptoms, respiratory problems and even death.

Headaches in children

Children of all ages experience headaches, but the causes aren't all the same. Here's how to help your child.

Heart attack

Heart failure

Heat exhaustion

Heatstroke

Hemolytic uremic syndrome (HUS)

Hemolytic uremic syndrome is an uncommon condition that can cause life-threatening kidney failure, especially for children and older adults.

Hemophilia

Henoch-Schonlein purpura

Henoch-Schonlein purpura causes inflammation of small blood vessels (vasculitis) and often a purplish rash. It's most common in children ages 2 to 6.

Hepatitis A

Hepatitis B

Hepatitis C

Hirschsprung's disease

Hirschsprung's disease, a disease of the colon, is present at birth and can cause serious problems passing stool.

Hydrocele

Hypercalcemia

Hyperglycemia in diabetes

Hyponatremia

Indigestion

Indigestion can ruin meals and make you feel uncomfortable. Take steps to prevent symptoms like upset stomach, bloating and pain.

Infant reflux

Spit up happens. Often, changes in feeding technique help keep reflux under control.

Intestinal ischemia

Intestinal obstruction

Intestinal obstruction — a serious condition that requires prompt medical attention — occurs when a blockage of the intestine prevents food or fluid from passing through.

Intracranial hematoma

Intussusception

A rare but serious disorder, intussusception occurs when one part of the intestine slides into an adjacent part, often causing intestinal obstruction.

Jellyfish stings

Kawasaki disease

Kawasaki disease — the leading cause of acquired coronary disease in children — causes artery wall inflammation throughout the body. It affects children younger than age 5.

Kidney stones

Krabbe disease

Krabbe disease is a rare, inherited disorder — most often affecting infants — that impairs functioning of the central nervous system and usually leads to early death.

Lactose intolerance

Lead poisoning

Legionnaires' disease

Legionnaires' disease, a severe form of pneumonia, is caused by bacteria that can live in water in air conditioning systems, showers and spas.

Listeria infection

Most people exposed to listeria don't become ill. But for those at risk of a listeria infection — a foodborne illness — the consequences can be severe.

Liver cancer

The risk of liver cancer may be reduced by protecting yourself from serious liver diseases such as cirrhosis and hepatitis B and C.

Liver disease

Liver hemangioma

Liver hemangioma is the most common type of noncancerous (benign) liver mass. Learn how doctors treat liver hemangioma.

Low blood pressure (hypotension)

Low blood pressure (hypotension) can be a sign of good health or of a life-threatening condition. Find out more about hypotension's causes and treatment options.

Malaria

Malaria is one of the oldest diseases on Earth and is still one of the leading killers.

Meningitis

Fever, headache and stiff neck are common signs and symptoms of meningitis — an infection of the membranes and fluid surrounding the brain and spinal cord.

Menstrual cramps

A monthly period is bad enough. Add in painful menstrual cramps, and you may be cursing this thing called womanhood. How do you get relief?

Mesenteric lymphadenitis

Mesenteric lymphadenitis is an inflammation of the lymph nodes in the tissue that attaches various organs to your abdominal wall (mesentery). It mainly affects children.

Migraine

A migraine isn't an ordinary headache. In addition to severe head pain, it can cause nausea, vomiting, and extreme sensitivity to light and sound.

Milk allergy

Molar pregnancy

Morning sickness

Multiple myeloma

Myocardial ischemia

Naegleria infection

Nonulcer stomach pain

Norovirus infection

Noroviruses cause an intestinal flu-like illness that typically resolves within days. Norovirus infection is highly contagious, especially in closed settings like hospitals and cruise ships.

Orchitis

Orthostatic hypotension (postural hypotension)

Orthostatic hypotension (postural hypotension) is a form of low blood pressure that occurs when you stand up.

Ovarian cancer

Ovarian cysts

Ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) — Comprehensive overview covers symptoms, treatment of this complication of infertility treatment.

Pancreatic cysts

Most cysts in the pancreas aren't malignant, but tests are needed to determine the best course of treatment.

Pancreatitis

The pain of pancreatitis, an inflammation of the pancreas, can last for days, or in chronic cases, for years. Pancreatitis can lead to serious complications.

Panic attacks and panic disorder

Parvovirus infection

Peanut allergy

Pelvic inflammatory disease (PID)

Peptic ulcer

Peptic ulcers are painful sores that commonly affect the lining of your stomach and upper small intestine. The most frequent cause is a treatable infection.

Peritonitis

Pinworm infection

Pituitary tumors

Pituitary tumors are abnormal growths in the pituitary gland in the brain. Most are noncancerous (benign). Some may cause overproduction of hormones and associated problems.

Plague

Plague is a disease carried by rats and other rodents. The risk of developing plague is low, and most cases occur in Africa.

Polio

One of the most feared diseases of the 20th century, polio has been eradicated from the developed world but remains a threat in less developed nations.

Polymorphous light eruption

Polymorphous light eruption is a sun-induced skin rash affecting people who develop a sensitivity to sunlight.

Porphyria

Porphyria is a group of inherited disorders that result from buildup of natural chemicals call porphyrins, which can cause nervous system and skin problems.

Postpartum preeclampsia

Preeclampsia

Pseudomembranous colitis

Pseudomembranous colitis is an inflammation of the colon that occurs most often in people using antibiotics.

Pseudotumor cerebri

Pseudotumor cerebri — Comprehensive overview covers symptoms, causes, treatment of increased pressure inside the skull.

Pyloric stenosis

Comprehensive overview covers symptoms, treatment of this uncommon digestive condition in infants.

Q fever

Radiation sickness

Radiation sickness is the effect of high doses of radiation on the body. The severity of illness depends on how much radiation the body absorbs.

Recurrent breast cancer

Reye's syndrome

Rocky Mountain spotted fever

Rotavirus

Rotavirus causes severe diarrhea in infants and children. Most cases can be treated at home with extra fluids.

Ruptured eardrum

A ruptured eardrum causes hearing loss and can give bacteria easy access to your middle ear. A ruptured eardrum usually heals without treatment.

Salmonella infection

Salmonella infection will cause only diarrhea and stomach pain in some people, but for infants and immunocompromised people, this bacterial illness can cause life-threatening complications.

Scarlet fever

Scarlet fever is a bacterial infection that causes a rash, fever and sore throat and usually affects children and adolescents.

Scrotal masses

Shaken baby syndrome


Shellfish allergy

Smallpox

Social anxiety disorder

Spider bites

Spider bites — Comprehensive overview covers symptoms, complications, treatment of spider bites.

Spinal headaches

Spontaneous coronary artery dissection (SCAD)

Find out about this rare cause of heart attack in young, healthy people.

Staph infections

Stomach cancer

Reduce your risk of stomach cancer by eating more fruits and vegetables.

Strep throat

Strep throat is a bacterial throat infection. It typically causes a very sore throat and is treated with antibiotics.

Sudden cardiac arrest

Sudden cardiac arrest is a medical emergency. Rapid treatment improves your chances of survival.

Swine flu (H1N1 flu)

Symptom Checker

Foot pain? Headache? Sore throat? Skin rash? Use the Symptom Checker to find out what's causing your symptom.

Tapeworm infection

Testicular torsion

Thunderclap headaches

Toxic hepatitis

Toxic hepatitis is liver damage that occurs when your liver isn't able to break down certain toxins — including common pain relievers such as Tylenol.

Toxic shock syndrome

Traumatic brain injury

While mild traumatic brain injury generally results in few long-term problems, more severe injury can cause several physical, emotional, behavioral, communication and cognitive problems.

Traveler's diarrhea

Traveler's diarrhea is unpleasant. Find out how to avoid this travel-related health problem.

Tularemia

Vasovagal syncope

Vasovagal syncope (fainting) is a sudden and brief loss of consciousness that occurs when the blood flow to your brain is markedly reduced.

Ventricular fibrillation

Wheat allergy

Whooping cough

Wilson's disease

Yellow fever

Zollinger-Ellison syndrome

In Zollinger-Ellison syndrome, tumors in the pancreas or duodenum secrete a hormone called gastrin that leads to excessive stomach acid and ulcers.

Sept. 04, 2014