DEFINITION Thyroid cancer occurs in the cells of the thyroid — a butterfly-shaped gland located at the base of your neck, just below your Adam’s apple. Your thyroid produces hormones that regulate your heart rate, blood pressure, body temperature and…
DEFINITION Thunderclap headaches live up to their name, grabbing your attention like a clap of thunder. The pain of these sudden, severe headaches peaks within 60 seconds and can start fading after an hour. Some thunderclap headaches, however, can last…
DEFINITION Stuttering — also called stammering or childhood-onset fluency disorder — is a speech disorder that involves frequent and significant problems with the normal fluency and flow of speech. People who stutter know what they want to say, but have…
DEFINITION Suicide, taking your own life, is a tragic reaction to stressful life situations — and all the more tragic because suicide can be prevented. Whether you’re considering suicide or know someone who feels suicidal, learn suicide warning signs and…
DEFINITION Sun allergy is a term often used to describe a number of conditions in which an itchy red rash occurs on skin that’s been exposed to sunlight. The most common form of sun allergy is polymorphic light eruption, also…
DEFINITION Sunburn — red, painful skin that feels hot to the touch — usually appears within a few hours after too much exposure to ultraviolet (UV) light from sunshine or artificial sources, such as sunlamps. Sunburn may take several days…
DEFINITION A breast lump is a growth of tissue that develops within your breast. Finding a lump in your breast can be frightening. Most breast lumps aren’t dangerous, but it’s important to see your doctor to have them evaluated promptly.…
DEFINITION Sweating and body odor are facts of life for most people. Heavy perspiration and body odor can happen when you exercise, when you’re too warm, or when you’re nervous, anxious or under stress. Your body has two main types…
DEFINITION Technically, the term “swine flu” refers to influenza in pigs. Occasionally, pigs transmit influenza viruses to people, mainly to hog farmers and veterinarians. Less often, someone infected passes the infection to others. The human respiratory infection caused by a…
DEFINITION A swollen knee occurs when excess fluid accumulates in or around your knee joint. Your doctor might refer to this condition as an effusion (ih-FYU-zhen) in your knee joint. Some people call this condition “water on the knee.” A…
DEFINITION Swollen lymph nodes usually occur as a result of exposure to bacteria or viruses. When swollen lymph nodes are caused by an infection, this is known as lymphadenitis (lim-fad-uh-NIE-tis). Rarely, swollen lymph nodes are caused by cancer. Your lymph…
DEFINITION Syphilis is a bacterial infection usually spread by sexual contact. The disease starts as a painless sore — typically on your genitals, rectum or mouth. Syphilis spreads from person to person via skin or mucous membrane contact with these…