DEFINITION Mittelschmerz is one-sided, lower abdominal pain associated with ovulation. German for “middle pain,” mittelschmerz occurs midway through a menstrual cycle — about 14 days before your next menstrual period. In most cases, mittelschmerz doesn’t require medical attention. For minor…
DEFINITION Mitral valve stenosis — or mitral stenosis — is a narrowing of the heart’s mitral valve. This abnormal valve doesn’t open properly, blocking blood flow into the main pumping chamber of your heart (left ventricle). Mitral valve stenosis can…
DEFINITION Mitral valve regurgitation — also called mitral regurgitation, mitral insufficiency or mitral incompetence — is a condition in which your heart’s mitral valve doesn’t close tightly, allowing blood to flow backward in your heart. As a result, blood can’t…
DEFINITION Mitral valve prolapse (MVP) occurs when the valve between your heart’s left upper chamber (left atrium) and the left lower chamber (left ventricle) doesn’t close properly. During mitral valve prolapse, the leaflets of the mitral valve bulge (prolapse) upward…
DEFINITION If you have a mold allergy, your immune system overreacts when you breathe in mold spores. This triggers a cascade of reactions that lead to allergic symptoms. Like other allergies, a mold allergy can make you cough, make your…
DEFINITION Moles are a common type of growth on the skin. They often appear as small, dark brown spots and are caused by clusters of pigmented cells. Moles generally appear during childhood and adolescence. Most people have 10 to 45…
DEFINITION Molluscum contagiosum (mo-LUS-kum kun-tay-jee-OH-sum) is a relatively common viral infection of the skin that results in round, firm, painless bumps ranging in size from a pinhead to a pencil eraser. If the bumps are scratched or injured, the infection…
DEFINITION If you have a mood disorder, your general emotional state or mood is distorted or inconsistent with your circumstances. Some examples of mood disorders include: Major depressive disorder — prolonged and persistent periods of extreme sadness …
DEFINITION Morning sickness is nausea that occurs during pregnancy. The name is a misnomer, however, since morning sickness can strike at any time of the day or night. Morning sickness affects a large proportion of pregnant women. It is most…
DEFINITION Morphea (mor-FEE-uh) is a rare skin condition that causes reddish or purplish patches on your skin. Morphea is a localized or limited form of scleroderma, a condition that can cause a wide variety of problems, from skin discoloration to…
DEFINITION Mosquito bites are the itchy bumps that appear after mosquitos use their mouthparts to puncture your skin and feed on your blood. Most mosquito bites are harmless, but occasionally a mosquito bite causes a large area of swelling, soreness…
DEFINITION Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by a strain of staph bacteria that’s become resistant to the antibiotics commonly used to treat ordinary staph infections. Most MRSA infections occur in people who’ve been in hospitals or other health…