The specific cause of lichen planus is not completely understood, but the condition may be associated with individuals who are infected with Hepatitis C and who have been exposed to chemicals, explains the American Skin Association. Lichen planus is not contagious and cannot be passed from person to person.
Lichen planus lesions in the mouth may also be linked to metal fillings, explains the American Academy of Dermatology. Experts also theorize that lichen planus lesions on the skin and inside the mouth may occur due to an autoimmune reaction in which the body reacts aggressively to foreign substances.
Symptoms of lichen planus include itchy, purple lesions on the skin and painful lesions inside the mouth, explains Healthline. Sufferers may also develop blisters that burst and scab over. Lichen planus skin lesions often spread into a rash within a few weeks to a few months of onset.
The condition usually clears on its own within six months to a year, but it is always best for individuals who suspect a lichen planus infection to consult with a physician to ensure a proper diagnosis, notes Healthline. In certain cases, individuals with lichen planus rashes may be advised to undergo testing for Hepatitis C. Treatments for the oral and skin lesions include antihistamine medications, corticosteroid injections and non-steroidal ointments.