In-depth

Acute kidney failure

Acute lymphocytic leukemia

Acute myelogenous leukemia (AML)

Amyloidosis

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

Aortic valve regurgitation

Aortic valve stenosis

Aplastic anemia

Aplastic anemia occurs when your bone marrow stops producing enough new blood cells. It's a serious problem, but treatments are available.

ARDS

Arteriovenous fistula

Ascariasis

Aspergillosis

Atrial septal defect

Atrioventricular canal defect

Bipolar disorder

Bradycardia

Bronchitis

Bronchitis often develops after a cold. Learn how to prevent this potentially serious lung infection.

Brucellosis

Brucellosis is an infectious disease that spreads from animals to people, mainly via unpasteurized dairy products. Travelers should take special care to avoid infection.

Brugada syndrome

Cancer

Cardiomyopathy

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

Cholera

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

Chronic fatigue syndrome

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.

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.

Concussion

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

Crohn's disease

Cyclospora infection

Cyclothymia (cyclothymic disorder)

Depression

Dermatomyositis

Diabetes

Diabetes affects how your body uses blood sugar. Too much blood sugar over long periods can cause serious health problems, but treatments are available.

Diabetic coma

Diabetic ketoacidosis

Dilated cardiomyopathy

Dumping syndrome

Encephalitis

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

Endocarditis

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

Esophageal cancer

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

Fibromyalgia

Fatigue and widespread pain are common with fibromyalgia, a condition affecting mainly women. Treatment often focuses on managing symptoms with medication and self-care.

Gaucher's disease

Generalized anxiety disorder

Giardiasis

Glomerulonephritis

Glomerulonephritis affects your kidneys' filtering function. Complications include high blood pressure, protein in the urine (proteinuria) and kidney failure.

Grand mal seizure

Graves' disease

Hairy cell leukemia

Hangovers

Hashimoto's disease

Hashimoto's disease (chronic lymphocytic thyroiditis) causes thyroid gland inflammation and often an underactive thyroid (hypothyroidism). Treatment may involve thyroid hormone replacement medication.

Heart attack

Heart disease

Heart disease, usually thought of as blockages in the arteries that can cause a heart attack, can describe any medical condition affecting your heart.

Heart failure

Heat exhaustion

Hemophilia

Hepatitis A

Hepatitis B

Hepatitis C

Hiatal hernia

HIV/AIDS

Hodgkin's lymphoma

Huntington's disease

Hypercalcemia

Hyperglycemia in diabetes

Hyperparathyroidism

Hyperthyroidism

Hyponatremia

Hypoparathyroidism

Hypothermia

Inflammatory bowel disease (IBD)

Influenza (flu)

Insomnia

Sleepless nights? Insomnia includes difficulty going to sleep, staying asleep or going back to sleep after you awaken. Insomnia may be temporary or chronic.

Iron deficiency anemia

Iron deficiency anemia may leave you feeling sapped of energy. This condition is especially common in women. Iron supplements usually help.

Jet lag disorder

Kidney cancer

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.

Leukemia

Long QT syndrome

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.

Lupus

Lyme disease

Male hypogonadism

Membranous nephropathy

Menorrhagia

Mental illness

Mitral valve prolapse

Mitral valve prolapse occurs when the valve separating two of your heart's chambers malfunctions. The disorder usually isn't serious and often doesn't require surgical treatment.

Mitral valve stenosis

Mixed connective tissue disease

Multiple myeloma

Mumps

Myelodysplastic syndromes

Myelofibrosis

In myelofibrosis, healthy bone marrow is replaced with scar tissue, leading to severe anemia and fatigue.

Myocarditis

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease is associated with obesity and diabetes. Lifestyle changes may prevent it from becoming serious.

Non-Hodgkin's lymphoma

Parvovirus infection

Pectus excavatum

Pelvic inflammatory disease (PID)

Pericarditis

Peritonitis

Pneumonitis

Pneumonitis is a general term for lung inflammation. It can cause difficulty breathing, often accompanied by a cough.

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.

Polycythemia vera

Polycythemia vera is a rare blood disorder in which a person's bone marrow makes too many blood cells.

Polymyalgia rheumatica

Polymyositis

Post-concussion syndrome

Postpartum depression

Post-polio syndrome

Prediabetes

Premenstrual syndrome (PMS)

Primary biliary cirrhosis

Primary sclerosing cholangitis

Pulmonary edema

Pulmonary fibrosis

Pulmonary fibrosis results from scar tissue that forms in your lungs. This affects your ability to breathe and obtain enough oxygen.

Pulmonary valve stenosis

Q fever

Rheumatic fever

Rheumatic fever, an inflammatory disease triggered by untreated or poorly treated strep throat, can cause permanent heart damage.

Rocky Mountain spotted fever

Roseola

Sheehan's syndrome

Sheehan's syndrome is a rare pituitary gland disorder that occurs in women usually as a result of severe blood loss during childbirth.

Shingles

Sick sinus syndrome

Sinus headaches

Sjogren's syndrome

Smallpox

Somatic symptom disorder

Sunburn: Soothing solutions

Swine flu (H1N1 flu)

Thalassemia

Thalassemia is an inherited blood disorder, characterized by less hemoglobin and fewer red blood cells than normal. When necessary, treatment includes blood transfusions.

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.

Toxoplasmosis

Toxoplasmosis is an infection caused by a parasite. It doesn't make most people ill, but infants and people with HIV/AIDS are at risk of complications.

Trench mouth

Although trench mouth is much less common than in years past, some people still get this painful gum infection. Brushing and flossing are keys to prevention.

Tricuspid atresia

Type 1 diabetes

Type 1 diabetes in children

Type 1 diabetes is a lifelong — sometimes frightening — condition, but it doesn't need to slow your child down. Learn more about managing type 1 diabetes.

Type 2 diabetes in children

Typhoid fever

Ulcerative colitis

Valley fever

Vasculitis

Vitamin deficiency anemia

Lacking certain vitamins can lead to vitamin deficiency anemia. Find out which vitamins are linked to this condition.

Von Willebrand disease

Von Willebrand disease is an inherited bleeding condition caused by a deficit in or impairment of a protein essential for blood clotting.

Whiplash

Whipple's disease

Whooping cough

Wilson's disease

Feb. 02, 2016