Causes of lichen planus 

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.

Lichen planus isn't infectious, doesn't usually run in families and can't be passed on to others.

Autoimmune reaction

The immune system protects your body against illness and infection by 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.

Reaction to medication

A reaction to certain medications is another possible cause of lichen planus. For example:

  • gold injections  these are disease-modifying anti-rheumatic drugs (DMARDs) that are sometimes injected into the muscles of people with arthritis to help reduce inflammation and painful joints
  • antimalarial tablets  these help treat and prevent malaria (a serious tropical disease spread by mosquitoes)

Page last reviewed: 08/10/2014

Next review due: 08/10/2016