All Diseases

You have flatfeet when the arch on the inside of your feet is flattened, allowing the entire sole of your foot to touch the floor when you stand up.

A common and usually painless condition, flatfeet may occur when the arches don't develop during childhood. In other cases, flatfeet may develop after an injury or from the simple wear-and-tear stresses of age.

Flatfeet can sometimes contribute to problems in your ankles and knees because the condition can alter optimal alignment of your legs. If you aren't experiencing any pain, no treatment is usually necessary for flatfeet.

Folliculitis is a common skin condition in which hair follicles become inflamed. It's usually caused by a bacterial or fungal infection. At first it may look like small red bumps or white-headed pimples around hair follicles — the tiny pockets from which each hair grows. The infection can spread and turn into nonhealing, crusty sores.

The condition isn't life-threatening, but it can be itchy, sore and embarrassing. Severe infections can cause permanent hair loss and scarring.

If you have a mild case, it'll likely clear in a few days with basic self-care measures. For more serious or recurring folliculitis, you may need to see a doctor.

Certain types of folliculitis are known as hot tub rash, razor bumps and barber's itch.

Food allergy is an immune system reaction that occurs soon after eating a certain food. Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives or swollen airways. In some people, a food allergy can cause severe symptoms or even a life-threatening reaction known as anaphylaxis.

Food allergy affects an estimated 6 to 8 percent of children under age 3 and up to 3 percent of adults. While there's no cure, some children outgrow their food allergy as they get older.

It's easy to confuse a food allergy with a much more common reaction known as food intolerance. While bothersome, food intolerance is a less serious condition that does not involve the immune system.

Food poisoning, also called foodborne illness, is illness caused by eating contaminated food. Infectious organisms — including bacteria, viruses and parasites — or their toxins are the most common causes of food poisoning.

Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.

Food poisoning symptoms, which can start within hours of eating contaminated food, often include nausea, vomiting or diarrhea. Most often, food poisoning is mild and resolves without treatment. But some people need to go to the hospital.

Foot drop, sometimes called drop foot, is a general term for difficulty lifting the front part of the foot. If you have foot drop, you may drag the front of your foot on the ground when you walk.

Foot drop isn't a disease. Rather, foot drop is a sign of an underlying neurological, muscular or anatomical problem.

Sometimes foot drop is temporary. In other cases, foot drop is permanent. If you have foot drop, you may need to wear a brace on your ankle and foot to hold your foot in a normal position.

Frontal lobe seizures are seizures that originate in the front of the brain. Epilepsy symptoms can vary depending on what part of the brain is involved. Frontal lobe seizures may produce unusual symptoms that can appear to be related to a psychiatric problem or a sleep disorder.

Frontal lobe seizures often occur during sleep and may feature bicycle pedaling motions and pelvic thrusting. Some people scream profanities or laugh during frontal lobe seizures.

In many cases of frontal lobe seizures, brain wave tests (electroencephalograms) may not show the changes characteristic of epileptic seizures that originate elsewhere in the brain. Medications usually can control frontal lobe seizures, but surgery is an option if anti-epileptic drugs aren't effective.

Frontotemporal dementia (frontotemporal lobar degeneration) is an umbrella term for a diverse group of uncommon disorders that primarily affect the frontal and temporal lobes of the brain — the areas generally associated with personality, behavior and language.

In frontotemporal dementia, portions of these lobes atrophy or shrink. Signs and symptoms vary, depending upon the portion of the brain affected. Some people with frontotemporal dementia undergo dramatic changes in their personality and become socially inappropriate, impulsive or emotionally indifferent, while others lose the ability to use language.

Frontotemporal dementia is often misdiagnosed as a psychiatric problem or as Alzheimer's disease. But frontotemporal dementia tends to occur at a younger age than does Alzheimer's disease, generally between the ages of 40 and 75.

Frostbite is an injury caused by freezing of the skin and underlying tissues. First your skin becomes very cold and red, then numb, hard and pale. Frostbite is most common on the fingers, toes, nose, ears, cheeks and chin. Exposed skin in cold, windy weather is most vulnerable to frostbite. But frostbite can occur on skin covered by gloves or other clothing.

Frostnip, the first stage of frostbite, doesn't cause permanent skin damage. You can treat very mild frostbite with first-aid measures, including rewarming your skin. All other frostbite requires medical attention because it can damage skin, tissues, muscle and bones. Possible complications of severe frostbite include infection and nerve damage.

Frozen shoulder, also known as adhesive capsulitis, is a condition characterized by stiffness and pain in your shoulder joint. Signs and symptoms typically begin gradually, worsen over time and then resolve, usually within one or two years.

Your risk of developing frozen shoulder increases if you're recovering from a medical condition or procedure that affects the mobility of your arm — such as a stroke or a mastectomy.

Treatment for frozen shoulder involves stretching exercises and, sometimes, the injection of corticosteroids and numbing medications into the joint capsule. In a small percentage of cases, surgery may be needed to loosen the joint capsule so that it can move more freely.

Fuchs' (fooks) dystrophy affects the cornea — the clear front window of your eye. This disorder causes swelling in the cornea that can lead to glare, cloudy vision and eye discomfort.

Fuchs' dystrophy usually affects both eyes and can cause your vision to gradually worsen over many years. But most people with Fuchs' dystrophy have a mild type and don't notice much change in their eyesight.

Some medications and self-care steps may help relieve your Fuchs' dystrophy signs and symptoms. But when the disorder is advanced and you've lost vision, the only way to restore vision is with cornea transplant surgery.