DEFINITION Hepatitis A is a highly contagious liver infection caused by the hepatitis A virus. The virus is one of several types of hepatitis viruses that cause inflammation and affect your liver’s ability to function. You’re most likely to contract…
DEFINITION Hemophilia is a rare disorder in which your blood doesn’t clot normally because it lacks sufficient blood-clotting proteins (clotting factors). If you have hemophilia, you may bleed for a longer time after an injury than you would if your…
DEFINITION Heart palpitations (pal-pih-TAY-shuns) are the feelings of having rapid, fluttering or pounding heart. Heart palpitations can be triggered by stress, exercise, medication or, rarely, a medical condition. Although heart palpitations can be worrisome, they’re usually harmless. In rare cases,…
DEFINITION Hepatitis C is an infection caused by a virus that attacks the liver and leads to inflammation. Most people infected with the hepatitis C virus (HCV) have no symptoms. In fact, most people don’t know they have the hepatitis…
DEFINITION Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). For some people, hepatitis B infection becomes chronic, meaning it lasts more than six months. Having chronic hepatitis B increases your risk of developing liver…
DEFINITION Hearing loss that occurs gradually as you age (presbycusis) is common. About one-third of people in the United States between the ages of 65 and 75 have some degree of hearing loss. For those older than 75, the number…
DEFINITION A hemangioma (he-man-jee-O-muh) is a birthmark that most commonly appears as a rubbery, bright red nodule of extra blood vessels in the skin. Sometimes called a strawberry mark, a hemangioma grows during the first year of life, and then…
DEFINITION Boils and carbuncles are painful, pus-filled bumps that form under your skin when bacteria infect and inflame one or more of your hair follicles. Boils (furuncles) usually start as red, tender lumps. The lumps quickly fill…
DEFINITION Body lice are tiny insects, about the size of a sesame seed. Body lice live in your clothing and bedding and travel to your skin several times a day to feed on blood. The most common sites for bites…
DEFINITION Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow or irregularly. Heart arrhythmias (uh-RITH-me-uhs) may feel like a fluttering or racing heart…
DEFINITION A hangover is a group of unpleasant signs and symptoms that can develop after drinking too much alcohol. As if feeling awful weren’t bad enough, frequent hangovers are also associated with poor performance and conflict at work. As a…
DEFINITION Soggy sheets and pajamas — and an embarrassed child — are a familiar scene in many homes. But don’t despair. Bed-wetting isn’t a sign of toilet training gone bad. It’s often just a normal part of a child’s development.…