Thecause of lichen planus is unknown.
It's thoughtto be related to the immune system, or an abnormal response of the immune system to certain medicines.
Lichen planus isn't infectious, doesn't usually run in families and can't be passed on to others.
The immune system protects your body against illness and infectionby producing antibodies (proteins)that attack bacteria and viruses.
In people with lichen planus, it's thought that the immune system becomes overactive, causing an excess amount of proteins to be produced, which inflame the skin. This is known as an autoimmune reaction and causes the symptoms of lichen planus .
A reaction to certain medications is another possible cause of lichen planus. For example:
Lichen planus is a non-infectious, itchy rash that can affect many areas of the body.
The symptoms of lichen planus vary, depending on which area of the body is affected. Affected areas can include the skin, mouth, penis and vulva.
The cause of lichen planus is unknown. It's thought to be related to the immune system, or an abnormal response of the immune system to certain medicines.
If you have lichen planus of the skin, your GP will examine the affected area and may be able to make a diagnosis based on the characteristic rash.
There's no cure for lichen planus, so treatments aim to ease the symptoms and clear the rash. Mild lichen planus doesn't require treatment.
Complications of lichen planus may include discoloured skin and, in some cases, erosive lichen planus may develop into certain types of cancer.
Dale Hodgson was diagnosed with oral lichen planus when she was 44, and has learnt to adapt her lifestyle in order to cope.
Bridget Nelson was diagnosed with a painful, erosive form of lichen planus that affected her mouth and vulva.