Lichen planus is a skin rash that is triggered by the immune system. It is not known why the immune response occurs. There may be several contributing factors, and each case is different. Potential causes include:
- viral infections
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 also not contagious.
However, there are some rare variations of the condition that may be 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.
Some of the most common symptoms of lichen planus include the following:
- purplish-colored lesions or bumps with flat tops on your skin or genitals
- lesions that develop and spread over the body during weeks or a few months
- itching at the site of the rash
- lacy white lesions in the mouth, which may be painful or cause a burning sensation
- blisters, which burst and become scabby
- thin white lines over the rash
The most common type of lichen planus affects the skin. Over the course of several weeks lesions appear and spread. The condition will usually clear up within six to 16 months.
Less commonly the lesions can occur in areas besides the skin or genitals. These may include:
- mucous membranes
- the scalp
There are also variations of the condition more common in the Middle East, Asia, Africa, and Latin America.
Causes and risk factors
Lichen planus develops when your body attacks your skin or mucous membrane cells by mistake. Doctors are not sure why this happens.
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 children and older adults. It is most common in middle-aged people.
Other risk factors include having family members who’ve had lichen planus, having a viral disease like hepatitis C, or being exposed to certain chemicals that act as allergens. These allergens may include:
- iodide compounds
- certain kinds of dyes
Anytime you see or feel a 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 your symptoms are making you very uncomfortable.
Your primary care 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.
Tests 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 medication.
There is no cure for lichen planus, but medications that treat the symptoms are helpful and some may even be able to target a possible underlying cause. Medications often prescribed include:
- retinoids, which are related to vitamin A and are taken topically or orally
- corticosteroids reduce inflammation and can be topical, oral, or given as an injection
- antihistamines reduce inflammation and may be particularly helpful if your rash is triggered by an allergen
- nonsteroidal creams are applied topically and can suppress your immune system and help clear up the rash
- light therapy treats lichen planus with ultraviolet light
There are other things you can try at home to complement your prescription treatments. These include:
- soaking in an oatmeal bath
- avoiding scratching
- applying cool compresses to the rash
- using OTC anti-itch creams
Talk to your doctor before adding OTC products to your treatment plan. This way you’ll be certain that nothing you might take will interact with prescription medications you’re taking.
Lichen planus can be difficult to treat if it develops on your vagina or vulva. This can lead to pain, scarring, and discomfort during sex.
Developing lichen planus can also increase your risk of squamous cell carcinoma. The increase in risk is small, but you should see your doctor for routine skin cancer examinations.
Lichen planus can be uncomfortable, but is not dangerous. With time, and a combination of home and prescription treatments, your rash will clear up.