All Diseases

Obstructive sleep apnea is a potentially serious sleep disorder in which breathing repeatedly stops and starts during sleep.

Several types of sleep apnea exist, but the most common type is obstructive sleep apnea, which occurs when your throat muscles intermittently relax and block your airway during sleep. The most noticeable sign of obstructive sleep apnea is snoring.

Anyone can develop obstructive sleep apnea, although it most commonly affects middle-aged and older adults and people who are overweight.

Obstructive sleep apnea treatment may involve using a device to keep your airway open or using a mouthpiece to thrust your jaw forward during sleep. Some people undergo a procedure to change the structure of their nose, mouth or throat.

Occupational asthma is asthma that's caused or worsened by breathing in chemical fumes, gases, dust or other substances on the job. Like other types of asthma, occupational asthma can cause chest tightness, wheezing and shortness of breath.

When treated early, occupational asthma may be reversible. Long-term exposure to allergy-causing substances can cause worsening symptoms and lifelong asthma.

Treatment for occupational asthma is similar to treatment for other types of asthma, and it generally includes taking medications to reduce symptoms. But the only sure way to eliminate your symptoms and prevent lung damage due to occupational asthma is to avoid whatever's triggering it.

Ocular rosacea (roe-ZAY-she-uh) is inflammation of the eye that occurs as a result of rosacea, a chronic, inflammatory condition that affects the skin on your face, nose and forehead. Many people with skin rosacea develop ocular rosacea, usually in combination with skin symptoms, but occasionally ocular rosacea occurs by itself.

Ocular rosacea primarily affects adults between the ages of 30 and 60. Ocular rosacea is more common in people with fair skin.

If you have skin rosacea, you may not realize that your ocular rosacea symptoms, such as dry eyes, are connected to the condition. There's no cure for ocular rosacea, and left untreated, it tends to get worse. There are medications to help you manage the condition.

Even the best-behaved children can be difficult and challenging at times. But if your child or teen has a frequent and persistent pattern of anger, irritability, arguing, defiance or vindictiveness toward you and other authority figures, he or she may have oppositional defiant disorder (ODD).

As a parent, you don't have to go it alone in trying to manage a child with ODD. Doctors, counselors and child development experts can help.

Treatment of ODD involves therapy, training to help build positive family interactions and skills to manage behaviors, and possibly medications to treat related mental health conditions.

Optic neuritis is an inflammation of the optic nerve, the bundle of nerve fibers that transmits visual information from your eye to your brain. Pain and temporary vision loss are common symptoms of optic neuritis.

Optic neuritis is highly associated with multiple sclerosis, a disease that causes inflammation and damage to nerves in your brain and spinal cord. In some people, signs and symptoms of optic neuritis may be the first indication of multiple sclerosis.

Most people who have a single episode of optic neuritis eventually recover their vision. Treatment with steroid medications may speed up vision recovery after optic neuritis.

Oral lichen planus (LIE-kun PLAY-nus) is an ongoing (chronic) inflammatory condition that affects mucous membranes inside your mouth. Oral lichen planus may appear as white, lacy patches; red, swollen tissues; or open sores. These lesions may cause burning, pain or other discomfort.

Oral lichen planus can't be passed from one person to another. The disorder occurs when the immune system mounts an attack against cells of the oral mucous membranes for unknown reasons (autoimmune disorder).

Symptoms can usually be managed, but people who have oral lichen planus need regular monitoring because they may be at risk of developing mouth cancer in the affected areas.

Oral thrush — also called oral candidiasis (kan-dih-DIE-uh-sis) — is a condition in which the fungus Candida albicans accumulates on the lining of your mouth. Candida is a normal organism in your mouth, but sometimes it can overgrow and cause symptoms.

Oral thrush causes creamy white lesions, usually on your tongue or inner cheeks. Sometimes oral thrush may spread to the roof of your mouth, your gums or tonsils, or the back of your throat.

Although oral thrush can affect anyone, it's more likely to occur in babies, the elderly, and in people with suppressed immune systems or certain health conditions, or those who take certain medications. Oral thrush is a minor problem if you're healthy, but if you have a weakened immune system, symptoms of oral thrush may be more severe and difficult to control.

Orchitis (or-KIE-tis) is an inflammation of one or both testicles. It is usually caused by a bacterial infection or by the mumps virus.

Bacterial orchitis can be caused by sexually transmitted infections (STIs), particularly gonorrhea or chlamydia. Bacterial orchitis often results from epididymitis, an inflammation of the coiled tube (epididymis) at the back of the testicle that stores and carries sperm. In that case, it's called epididymo-orchitis.

Orchitis causes pain and can affect fertility. Medication can treat the causes of bacterial orchitis and can ease some signs and symptoms of viral orchitis. But it may take several weeks for scrotal tenderness to disappear.

Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint.

Orthostatic hypotension is often mild, lasting a few seconds to a few minutes after standing. However, long-lasting orthostatic hypotension can be a sign of more-serious problems, so talk to your doctor if you frequently feel lightheaded when standing up. It's even more urgent to see a doctor if you lose consciousness, even momentarily.

Mild orthostatic hypotension often doesn't need treatment. Many people occasionally feel dizzy or lightheaded after standing, and it's usually not cause for concern. The treatment for more-severe cases of orthostatic hypotension depends on the cause.

Osgood-Schlatter disease can cause a painful lump below the kneecap in children and adolescents experiencing growth spurts during puberty.

Osgood-Schlatter disease occurs most often in children who participate in sports that involve running, jumping and swift changes of direction — such as soccer, basketball, figure skating and ballet.

While Osgood-Schlatter disease is more common in boys, the gender gap is narrowing as more girls become involved with sports.

Age ranges differ by sex because girls experience puberty earlier than do boys. Osgood-Schlatter disease typically occurs in boys ages 13 to 14 and girls ages 11 to 12. The condition usually resolves on its own, once the child's bones stop growing.