Lichen planus is a common disease that causes inflammation (swelling and irritation) on your skin or inside your mouth. On your skin, lichen planus causes a rash that is usually itchy. Inside your mouth, it may cause burning or soreness.

The cause of lichen planus is usually not known, although possible causes include:

• Hepatitis C, a virus that attacks your liver

• Certain medicines, including some drugs used to treat high blood pressure, diabetes, heart disease, and malaria

• Reactions to metal fillings in your teeth

• An autoimmune reaction, meaning the body's own defense system, the immune system, attacks your mouth and skin cells by mistake

Symptoms

Symptoms of lichen planus depend on the part or parts of your body affected. Common symptoms include:

• Skin: The most common symptoms are shiny red or purple bumps. These bumps are firm and may itch a little or a lot; you may have just a few or many of them. Fine white lines or scales may accompany the bumps. They can occur anywhere, but are most common on your wrists, arms, back, and ankles. Thick scaly patches may appear on your shins and ankles. Sometimes, bumps on your skin may appear in an area where your skin has been scratched or burned. Dark skin patches may replace skin bumps that fade. These patches usually fade away after many months.

• Mouth: Lichen planus inside your mouth looks like lacy patches of tiny white dots. These patches may occur on the inside of your cheeks or on your tongue. They may not cause any other symptoms; in severe cases, redness and sores develop.

• Nails: Lichen planus may appear on a few, or all, of your fingernails and toenails. Thinning, ridges, splitting, and nail loss are signs of the condition.

• Scalp: Redness, irritation, and tiny bumps can form on your scalp. In some cases, hair may start to thin and patches of hair loss may occur.

• Genitals: Lichen planus in your genitals can cause bright red, painful areas.

Who’s at risk?

About 1 in 100 people will get lichen planus at some time. It is not caused by an infection, and you can’t pass it on to others. Lichen planus usually affects men and women in middle age. Equal numbers of men and women get lichen planus of the skin, but women are twice as likely to get oral (inside the mouth) lichen planus. The disease is rare in people who are very young or very old.

Diagnosis

Your doctor or dentist may diagnose lichen planus, based on the changes on your skin or in your mouth. To make sure of the diagnosis, your doctor will perform a biopsy. He or she will remove mouth mucosa, or a small piece of skin, and send it to be examined it under a microscope.

Treatment

If your biopsy shows lichen planus and you have no symptoms, you probably do not need treatment. In most cases, lichen planus will go away within 2 years. If you have symptoms, such as severe itching or sores in your mouth or genital area, treatment can help. If you have lichen planus on your scalp, treatment is important to prevent permanent hair loss.

Lichen planus has no cure, but different treatments can help relieve your symptoms and speed healing. Possible treatments include:

• Antihistamine medicine to relieve itching

• Steroids on your skin or in your mouth to fight inflammation (You may also take steroids in pill form for severe cases)

• A type of ultraviolet light treatment called PUVA

• Retinoic acid, a medicine derived from vitamin A and usually used for acne

• Tacrolimus and pimecrolimus, ointments used for eczema.

Complications

Some evidence suggests that oral lichen planus may be an early warning for oral cancer. Make sure you see your dentist for an oral exam at least twice a year.

When to call the doctor

If you have any symptoms of lichen planus, talk with your doctor. You may need to see a dermatologist for the most effective care.

How to manage or live with the condition

You can’t do much to prevent lichen planus, but once you have it, you can take steps to keep it from getting worse.

• Avoid injuries to your skin.

• Apply cool compresses instead of scratching.

• Limit the stress in your life.

• For oral lichen planus, stop smoking, avoid alcohol, maintain good oral hygiene, and avoid any foods that seem to irritate your mouth.

Lichen planus is not a dangerous disease, and it usually goes away on its own. However, in some people, it may come back.