In-depth

Acromegaly

Acute kidney failure

Acute lymphocytic leukemia

Acute myelogenous leukemia (AML)

Acute sinusitis

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.

Anemia

Angina

Anorexia nervosa

Anthrax

Anxiety

Aortic valve regurgitation

Aortic valve stenosis

Aplastic anemia

ARDS

Arteriovenous fistula

Ascariasis

Aspergillosis

Atrial septal defect

Atrioventricular canal defect

Autoimmune hepatitis

Bipolar disorder

Blastocystis hominis infection

Bone cancer

Bradycardia

Bronchitis

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

Brucellosis

Brugada syndrome

Cancer

Cardiomyopathy

Castleman disease

Celiac disease

Chagas disease

Chemo brain

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 lymphocytic leukemia

Chronic myelogenous leukemia

Chronic sinusitis

Churg-strauss syndrome

Cirrhosis

Colon cancer

Common cold

Concussion

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

Crohn's disease

Cushing syndrome

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

Ebstein's anomaly

Encephalitis

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

Endocarditis

Endometriosis

Enlarged liver

Enlarged spleen (splenomegaly)

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

Granulomatosis with polyangiitis

Graves' disease

Hairy cell leukemia

Hangovers

Hashimoto's disease

Heart arrhythmias

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

Hemochromatosis

Hemolytic uremic syndrome (HUS)

Hemophilia

Hepatitis A

Hepatitis B

Hepatitis C

Hiatal hernia

Hirschsprung's disease

HIV/AIDS

Hodgkin's lymphoma

Huntington's disease

Hypercalcemia

Hyperglycemia in diabetes

Hyperparathyroidism

Hyperthyroidism

Hypertrophic cardiomyopathy

Hyponatremia

Hypoparathyroidism

Hypopituitarism

Hypothermia

Hypothyroidism

Inflammatory bowel disease (IBD)

Influenza (flu)

Insomnia

Iron deficiency anemia

Jet lag disorder

Kidney cancer

Lead poisoning

Legionnaires' disease

Leukemia

Liver cancer

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 regurgitation

Mitral valve stenosis

Mixed connective tissue disease

Mononucleosis

Multiple myeloma

Multiple sclerosis

Mumps

Myelodysplastic syndromes

Myelofibrosis

Myocarditis

Non-Hodgkin's lymphoma

Parvovirus infection

Pectus excavatum

Pelvic inflammatory disease (PID)

Pericarditis

Peritonitis

Persistent depressive disorder (dysthymia)

Plague

Pneumonia

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 atresia

Pulmonary edema

Pulmonary fibrosis

Pulmonary hypertension

Pulmonary valve stenosis

Q fever

Rheumatic fever

Rheumatoid arthritis

Rocky Mountain spotted fever

Roseola

Sarcoidosis

Sheehan's syndrome

Shingles

Sick sinus syndrome

Sinus headaches

Sjogren's syndrome

Small vessel disease

Smallpox

Somatic symptom disorder

Stomach cancer

Strep throat

Sudden cardiac arrest

Sunburn: Soothing solutions

Swine flu (H1N1 flu)

Takayasu's arteritis

Teen depression

Thalassemia

Toxic hepatitis

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

Tricuspid valve regurgitation

Tuberculosis

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

Type 2 diabetes in children

Typhoid fever

Ulcerative colitis

Valley fever

Vasculitis

Viral hemorrhagic fevers

Vitamin deficiency anemia

Von Willebrand disease

West Nile virus

Whiplash

Whipple's disease

Whooping cough

Wilson's disease

Feb. 02, 2016