Lichen planus

Lichen planus is an itchy rash that can show up on many parts of the body, including inside the mouth. It isn't infectious.

Lichen planus doesn't look or feel the same for everyone. The symptoms you get depend on which part of the body is affected.

Lichen planus often shows up on the wrists, ankles and lower back, but it can appear anywhere on the body.

It can cause purple-red bumps (papules) that are slightly raised, shiny and flat on top. The papules usually measure 3 to 5mm, and they may have irregular white streaks. Once the papules have cleared, the skin can sometimes stay discoloured.

Lichen planus can also cause thick, scaly patches of skin. This is known as hypertrophic lichen planus.

The rash may be itchy as well.

Oral lichen planus can show up in a few different ways:

• a white pattern on the tongue and inner cheeks
• red and white patches in the mouth
• burning and discomfort in the mouth while eating or drinking
• painful red gums

If you have a mild form of oral lichen planus, you usually won't have any pain or discomfort.

Lichen planus on the penis can cause a few signs you may notice:

• purple or white ring-shaped patches on the tip of the penis
• bumps (papules) that are flat-topped and shiny
• a non-itchy rash

Lichen planus on the vulva and vagina can cause these symptoms:

• soreness, burning and rawness around the vulva
• white streaks on the vulva
• redness, pinkness or a pale white colour on the vulva
• pain during sex
• moist, red patches
• a change in shape of the vagina caused by scar tissue
• sticky yellow or green discharge, which may be bloodstained
• narrowing of the vagina

Lichen planus can sometimes affect other areas of the body, including the nails. The nails may become thinner, ridged and grooved, or they may turn darker, thicker or raised. Sometimes they shed or stop growing.

The scalp can be affected too. You may notice red patches around clusters of hair. Some people end up with permanent hair loss.

A doctor can usually diagnose lichen planus by looking at your rash and asking about your symptoms.

Oral lichen planus, the kind that affects the mouth, is often picked up by a dentist during a routine dental check-up.

Some conditions, such as eczema or psoriasis, look quite similar to lichen planus. So sometimes you may need a skin biopsy to find out exactly what is causing your symptoms.

If you do need a skin biopsy, you'll be given a local anaesthetic to numb the affected area. This means you won't feel any pain or discomfort during the procedure.

Lichen planus usually clears up on its own within 6 to 9 months. Creams and ointments from your doctor can help to relieve itching and control the rash.

If creams and ointments don't work, or your lichen planus is severe, you may need other treatments. These include steroid tablets or treatment with a special kind of light (light therapy).

Oral lichen planus, and lichen planus in the genital area, may last longer. Mouthwashes and sprays from a doctor can help ease symptoms like burning or sore gums.

There are a few things you can do at home to ease the symptoms of lichen planus. What will help depends on which part of your body is affected.

If you have lichen planus on your skin, these steps can help:

• wash with warm water, and avoid soap, bubble bath or body wash
• wash your hair over a basin so the shampoo doesn't touch the rest of your skin
• use an emollient to moisturise your skin
• try not to scratch the rash

If you have lichen planus in your mouth, a few simple habits can help:

• eat soft, bland foods like mashed potatoes and porridge if your mouth is sore
• use your usual toothpaste, if possible
• keep your mouth as clean as possible
• visit your dentist regularly to help keep your teeth and gums healthy

If your mouth is sore, try to avoid:

• spicy foods
• acidic food and drinks like fruit juice
• sharp foods like crusty bread
• alcohol, particularly spirits
• mouthwashes that contain alcohol

If you have lichen planus on your genitals, a few simple habits can help:

• wash in warm water, and avoid soap or bubble bath
• use an emollient, like petroleum jelly, before and after urinating
• avoid wearing tights or tight-fitting clothes
• try to have showers instead of baths
• dry yourself carefully after going to the toilet, to reduce the chance of pee touching your skin
• use a lubricant if sex is painful

You can also put an ice pack on the area to soothe itching and swelling. Don't put the ice pack directly on your skin. Wrap it in a clean tea towel first, then place it on your body.

Nobody knows the exact cause of lichen planus. It may have something to do with the immune system, or with an abnormal reaction of the immune system to certain medicines.

Lichen planus isn't infectious, so you can't pass it on to other people, including sexual partners. It doesn't usually run in families.

Lichen planus is more common in adults over the age of 40. Men and women are affected equally. The exception is oral lichen planus, which is more common in women.

Once the lichen planus rash has cleared, your skin may not go back to its original colour. You might be left with a brown or grey mark, and it can sometimes stay for months. Doctors call this post-inflammatory hyperpigmentation. It tends to show up more clearly in people with darker skin.

Erosive lichen planus is a rare form of lichen planus, and it can last a long time. It causes painful ulcers to form in the mouth and in the genital area.

In some cases, if you have had erosive lichen planus for many years, it can raise the chance of some types of cancer developing.