The cause of lichen planus is unknown. However, it is thought that causes of the condition may be related to:
- the immune system (the body’s natural defence against infection and illness)
- a reaction to certain types of medication
Autoimmune reaction
The immune system protects your body against infection and produces antibodies (proteins) that attack bacteria and viruses.
In people with lichen planus, it is thought that the immune system becomes overactive, causing an excess amount of proteins to be produced, which leads to the skin becoming inflamed. This is known as an autoimmune reaction in the body, and it causes the symptoms that are associated with the condition.
Reaction to medication
Another possible cause of lichen planus is a reaction in the body to certain medications. For example:
- gold injections: these are disease-modifying anti-rheumatic drugs (DMARDs), which are sometimes injected into the muscles of people with arthritis to help reduce swelling (inflammation) and painful joints
- antimalarial tablets: these help to treat and prevent malaria (a tropical disease spread by infected mosquitoes)
Lichen planus is not infectious, does not usually run in families and cannot be passed on to others.
