Lichen planus is a fairly common skin rash that is thought to be triggered by the immune system. Exactly why the immune response occurs is not known. There may be several contributing factors, and each case is different. Potential causes include viral infections, an allergen, or even stress or genetics. Sometimes lichen planus occurs along with autoimmune disorders.
While it may be uncomfortable, in most cases lichen planus is not a serious condition. It is not contagious. There are some rare variations of the condition that are more serious and painful. It can be treated by using topical and oral medications to reduce symptoms, or by using drugs that suppress the immune system.
Lichen planus can occur in anyone at any age, but there are certain factors that make some people more likely to develop the condition. The skin form of lichen planus occurs in men and women equally, but women are twice as likely to get the oral form. It is very rare in young and elderly people, and most common in middle-aged people.
Other risk factors include having other family members with lichen planus, having a viral disease like hepatitis C, or being exposed to certain chemicals that may act as allergens. These could be antibiotics, arsenic, gold, iodide compounds, diuretics, and certain kinds of dyes.
Some of the most common symptoms of lichen planus include the following:
- purplish-colored lesions, or bumps, with flat tops (mostly found on the wrist, inner forearm, or ankles, but can be anywhere)
- lesions that develop and spread over the course of two weeks to a few months
- itching at the site of the rash
- lesions in the mouth, which may be painful or cause a burning sensation
- blisters, which become scabby after bursting
- thin white lines over the rash
The most common type of lichen planus affects the skin. The lesions appear and spread over the course of several weeks and usually clear up within six months to a year and a half. Less commonly the lesions can occur on mucous membranes, genitalia, nails, and the scalp. There are also variations of the condition that are more common in the Middle East, Asia, Africa, and Latin America.
Anytime you see or feel a new type of rash on your skin or lesions in your mouth or on your genitals, you should see your doctor as soon as possible. Your primary care doctor may send you to a dermatologist if a diagnosis of lichen planus is not obvious, or if you have more than mild, uncomfortable symptoms.
Your doctor or dermatologist may be able to tell that you have lichen planus simply by looking at your rash. To confirm the diagnosis, you may need further tests. These could include a biopsy, which means taking a small sample of your skin cells to view under a microscope, or an allergy test to find out if you are having an allergic reaction. If your doctor suspects the underlying cause is an infection, you may need to have a test for hepatitis C.
For mild cases of lichen planus, which usually clear up in weeks or months, you may not need any treatment. If the symptoms are uncomfortable or severe, your doctor can prescribe certain medications that may help. There is no cure for the condition, but medications that treat the symptoms are helpful and some may even be able to target a possible underlying cause. Possible medications include one or more of the following:
- retinoids: Retinoids are medications that are related to vitamin A. They can be used topically or taken orally to treat your rash.
- corticosteroids: These help to reduce the inflammation of a lichen planus rash, and can be topical, oral, or given as an injection.
- antihistamines: These also reduce inflammation and may be particularly helpful if your rash is triggered by an allergen.
- nonsteroidal creams: There are topical creams available that can suppress your immune system and help clear up the rash.
- light therapy: In some cases, treating lichen planus with ultraviolet light seems to help.
Lichen planus is rarely severe and, although it can be uncomfortable, is not a dangerous condition to have. With treatment and time, your rash will clear up and you will once again have normal skin.