Diseases and Conditions

Find doctor-approved information about symptoms, causes, diagnosis, treatment and prevention of common diseases and conditions.

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  • Milk and cheese on a table. Lactose intolerance is a condition that causes stomach discomfort. It’s your body reacting to the sugar in milk (or other dairy).

    Lactose Intolerance

    Lactose intolerance is a condition that causes stomach discomfort. It’s your body reacting to the sugar in milk (or other…

  • A doctor wearing blue latex gloves

    Latex Allergy

    Natural rubber latex comes from a liquid in tropical rubber trees. The protein in this rubber can cause an allergic…

  • A person sits in a chair and rubs their foot with their hand. Leprosy is a chronic infection caused by bacteria. It can affect the skin, nerves, eyes, and nose. It’s also called Hansen’s disease.

    Leprosy

    Leprosy is a chronic infection caused by bacteria. It can affect the skin, nerves of the hands and feet, eyes,…

  • A close-up photo of a young girl without hair. Leukemia is a cancer involving the body’s white blood cells and bone marrow. It is most common in adults over 60, but kids can also get it.

    Leukemia

    Leukemia is a blood cancer involving your body’s bone marrow.

  • A man scratches an itch on his wrist. Lichen planus is a rash that forms on your skin, genitalia, or in your mouth. It is marked by purple bumps that are flat and uneven in size.

    Lichen Planus

    Lichen planus is a type of rash that forms on your skin, on genitalia, or in your mouth.

  • woman with hands holding her crotch

    Lichen Sclerosus

    Lichen sclerosus is a skin condition that affects the genital or anal areas. It can cause a rash, itching, pain,…

  • A lipoma under the skin by the elbow. Lipomas are slow-growing tumors that come from fat cells. They are usually round, moveable lumps under the skin.

    Lipomas

    Lipomas are slow-growing tumors that come from fat cells. They are usually round, moveable lumps under the skin.

  • Long COVID: Symptoms and Treatment

    Most people who get sick with COVID-19 will recover within a week or even a few days. But for some,…

  • Athletic woman standing outside, rubbing lower back muscles. Low back pain is a common problem and has many possible causes, including injury, pregnancy and poor posture.

    Low Back Pain

    Low back pain is common and has many causes, including injury, pregnancy, even poor posture.

  • A man in office clothes holding his back in pain

    Lumbar Spinal Canal Stenosis

    Lumbar spinal canal stenosis is when the canal in your lower spine narrows, squeezing the nerves in it. It’s treated…

  • A female doctor examines X-ray of a patient’s lungs looking for signs of lung cancer. Lung cancer is abnormal growth of cells in the lungs. It is one of the most common forms of cancer in the world.

    Lung Cancer

    Lung cancer is abnormal growth of cells in the lungs.

  • A doctor uses a stethoscope while examining a patient. Lupus is a disease that affects your immune system. Lupus symptoms can affect many parts of the body, including the joints, skin, and organs.

    Lupus

    Lupus is a disease that affects your immune system, causing it to attack healthy cells and tissue.

  • Lyme Disease

    Lyme disease is a bacterial infection caused by a tick bite.

  • A swollen foot caused by lymphedema. Lymphedema occurs when there is excess fluid inside your body. It causes swelling in your arms, legs, fingers, and toes.

    Lymphedema

    Lymphedema is a condition often caused by cancer treatment or surgery. It results in swelling of the lymph nodes located…

  • Cows peak their heads out of their stalls in a barn. Mad cow disease is a rare and deadly brain disease spread by eating beef products from a cow that has been infected. There is no cure.

    Mad Cow Disease

    Mad cow disease is a rare and deadly brain disease spread by eating beef products from a cow that has…

  • A mosquito sits on human skin

    Malaria

    Malaria is a serious disease caused by a parasite. The parasite is carried by one type of mosquito. Humans get…

  • Close-up of a pink ribbon (the symbol of breast cancer awareness) in a man’s hands

    Male Breast Cancer

    Breast cancer is a type of cancer that begins in the breast. Men can get breast cancer even though it…

  • close-up of a young man in jeans holding a baseball in his hand

    Mallet Finger

    Mallet finger is an injury to your fingertip that prevents you from straightening it. It is common in sports, especially…

  • colleagues wear protective facemasks during a meeting at work

    Mass Psychogenic Illness

    Mass psychogenic illness is sometimes called mass hysteria. It is when a group of people starts feeling sick at the…

  • a mother breastfeeds her baby

    Mastitis

    Mastitis is an inflammation of the breast usually caused by an infection.