All Diseases

Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you're allergic to, such as a peanut or the venom from a bee sting.

The flood of chemicals released by your immune system during anaphylaxis can cause you to go into shock; your blood pressure drops suddenly and your airways narrow, blocking normal breathing. Signs and symptoms of anaphylaxis include a rapid, weak pulse, a skin rash, and nausea and vomiting. Common triggers of anaphylaxis include certain foods, some medications, insect venom and latex.

Anaphylaxis requires an immediate trip to the emergency department and an injection of epinephrine. If anaphylaxis isn't treated right away, it can lead to unconsciousness or even death.

Anemia is a condition in which you don't have enough healthy red blood cells to carry adequate oxygen to your tissues. Having anemia may make you feel tired and weak.

There are many forms of anemia, each with its own cause. Loss of blood is the most common cause of anemia. Anemia can be temporary or long term, and it can range from mild to severe.

Treatments for anemia range from taking supplements to undergoing medical procedures. You may be able to prevent some types of anemia by eating a healthy, varied diet.

See your doctor if you suspect you have anemia because anemia can be a sign of serious illnesses.

Angelman syndrome is a genetic disorder that causes developmental disabilities and neurological problems, such as difficulty speaking, balancing and walking, and, in some cases, seizures. Frequent smiles and outbursts of laughter are common for people with Angelman syndrome, and many have happy, excitable personalities.

Angelman syndrome usually isn't detected until parents begin to notice developmental delays when a baby is about 6 to 12 months old. Seizures often begin when a child is between 2 and 3 years old.

People with Angelman syndrome tend to live a normal life span. But they may become less excitable and develop sleep problems that may improve with age. Treatment focuses on managing medical and developmental issues.

Angina is a term used for chest pain caused by reduced blood flow to the heart muscle. Angina (an-JIE-nuh or AN-juh-nuh) is a symptom of coronary artery disease. Angina is typically described as squeezing, pressure, heaviness, tightness or pain in your chest.

Angina, also called angina pectoris, can be a recurring problem or a sudden, acute health concern.

Angina is relatively common but can be hard to distinguish from other types of chest pain, such as the pain or discomfort of indigestion. If you have unexplained chest pain, seek medical attention right away.

Anhidrosis is the inability to sweat normally. When you don't sweat (perspire), your body can't cool itself, which can lead to overheating and sometimes to heatstroke — a potentially fatal condition.

Anhidrosis — sometimes called hypohidrosis — can be difficult to diagnose. Mild anhidrosis often goes unrecognized. Dozens of factors can cause the condition, including skin trauma and certain diseases and medications. You can inherit anhidrosis or develop it later in life.

Treatment of anhidrosis involves addressing the underlying cause, if one can be found.

Ankylosing spondylitis is an inflammatory disease that can cause some of the vertebrae in your spine to fuse together. This fusing makes the spine less flexible and can result in a hunched-forward posture. If ribs are affected, it may be difficult to breathe deeply.

Ankylosing spondylitis affects men more often than women. Signs and symptoms of ankylosing spondylitis typically begin in early adulthood. Inflammation also can occur in other parts of your body — most commonly, your eyes.

There is no cure for ankylosing spondylitis, but treatments can decrease your pain and lessen your symptoms.

Anorexia (an-o-REK-see-uh) nervosa — often simply called anorexia — is an eating disorder characterized by an abnormally low body weight, intense fear of gaining weight and a distorted perception of body weight. People with anorexia place a high value on controlling their weight and shape, using extreme efforts that tend to significantly interfere with activities in their lives.

To prevent weight gain or to continue losing weight, people with anorexia usually severely restrict the amount of food they eat. They may control calorie intake by vomiting after eating or by misusing laxatives, diet aids, diuretics or enemas. They may also try to lose weight by exercising excessively.

Some people with anorexia binge and purge, similar to individuals with bulimia nervosa. However, people with anorexia generally struggle with an abnormally low body weight, while individuals with bulimia typically are normal to above normal weight. No matter how weight loss is achieved, the person with anorexia has an intense fear of gaining weight.

Anorexia isn't really about food. It's an unhealthy way to try to cope with emotional problems. When you have anorexia, you often equate thinness with self-worth.

Anorexia can be very difficult to overcome. But with treatment, you can gain a better sense of who you are, return to healthier eating habits and reverse some of anorexia's serious complications.

Anorgasmia is the medical term for regular difficulty reaching orgasm after ample sexual stimulation, causing you personal distress. Anorgasmia is a common occurrence, affecting a significant number of women.

Orgasms vary in intensity, and women vary in the frequency of their orgasms and the amount of stimulation necessary to trigger an orgasm. In fact, most women don't consistently have orgasms with vaginal penetration alone. Plus, orgasms often change with age, medical issues or medications you're taking.

If you're happy with the climax of your sexual activities, there's no need for concern. However, if you're bothered by lack of orgasm or the intensity of your orgasms, talk to your doctor about anorgasmia. Lifestyle changes and sex therapy may help.

Anterior prolapse, also known as a cystocele (SIS-toe-seel), occurs when the supportive tissue between a woman's bladder and vaginal wall weakens and stretches, allowing the bladder to bulge into the vagina. Anterior prolapse is also called a prolapsed bladder.

Straining the muscles that support your pelvic organs may lead to anterior prolapse. Such straining occurs during vaginal childbirth or with chronic constipation, violent coughing or heavy lifting. Anterior prolapse also tends to cause problems after menopause, when estrogen levels decrease.

For a mild or moderate anterior prolapse, nonsurgical treatment is often effective. In more severe cases, surgery may be necessary to keep the vagina and other pelvic organs in their proper positions.

Anthrax is a rare but serious illness caused by a spore-forming bacterium, Bacillus anthracis. Anthrax mainly affects livestock and wild game. Humans can become infected through direct or indirect contact with sick animals.

There's no evidence that anthrax is transmitted from person to person, but it's possible that anthrax skin lesions may be contagious through direct contact. Usually, anthrax bacteria enter the body through a wound in the skin. You can also become infected by eating contaminated meat or inhaling the spores.

Signs and symptoms, which depend on how you're infected, can range from skin sores to vomiting to shock. Prompt treatment with antibiotics can cure most anthrax infections. Inhaled anthrax is more difficult to treat and can be fatal.