Although the cause of lichen planus is unknown, some people with the condition also have hepatitis C, an infection of the liver.
People who take certain medications may develop a rash that looks like lichen planus (drug-induced lichen planus). These medications include:
- High blood pressure (hypertension) medicines, including diuretics, ACE inhibitors, and calcium channel blockers
- Diabetes medications, including the sulfonylureas
- Ibuprofen or naproxen
- Antimalarial medications
- Inner wrists
- Inner ankles
- Lower legs
- Inside the mouth
- Fingernails and toenails
New lesions of lichen planus can be caused by injury (trauma). This so-called Koebner phenomenon may appear as a line of flat-topped, red-to-purple bumps on the skin.
Once they heal, lichen planus lesions often leave behind patches of darker (hyperpigmented) skin, which are more pronounced in darker-skinned people and which may take months to return to their normal color.
In the mouth, lichen planus appears as white, net-like patches, most often seen on the inner cheeks. This oral lichen planus does not usually cause symptoms, though severe outbreaks may develop painful sores and ulcers in the mouth.
When lichen planus involves one or more fingernails or toenails, it can appear as thickening, splitting, ridges, or grooves. In severe outbreaks, the entire nail may be destroyed.
On the scalp, lichen planus (called lichen planopilaris) may cause redness, irritation, and, in some cases, permanent hair loss.
On the penis, lichen planus appears similar to lesions on other areas of the skin. In the vulva or vagina, lichen planus may appear as bright red patches or sores. Genital lichen planus does not usually cause symptoms, but open sores may be quite tender.
- Apply over-the-counter hydrocortisone cream to help relieve itching in mild lichen planus.
- If you have lichen planus in the mouth, avoid drinking alcohol and using tobacco products. In severe outbreaks of oral lichen planus, there is a very small chance of developing oral cancer, so you should see your dentist twice a year to check for oral cancer.
- Numbing the skin with an injectable anesthetic.
- Sampling a small piece of skin by using a flexible razor blade, a scalpel, or a tiny cookie cutter (called a "punch biopsy"). If a punch biopsy is taken, a stitch (suture) or 2 may be placed and will need to be removed 6–14 days later.
- Having the skin sample examined under the microscope by a specially trained physician (dermatopathologist).
- Topical corticosteroid (cortisone) cream, lotion, ointment, or gel
- Topical tacrolimus or pimecrolimus
- Anti-itch lotions containing menthol, pramoxine, or phenol
- Corticosteroid (cortisone) injected directly into a thick lesion
- Oral antihistamine pills such as diphenhydramine, loratadine, cetirizine, fexofenadine, desloratadine, or hydroxyzine for itching
- Topical corticosteroid (cortisone) ointment or gel
- Topical cyclosporine solution used as a mouthwash
- Ultraviolet light treatment
- Oral retinoid pills such as isotretinoin or acitretin
- Oral cyclosporine pills
- Oral hydroxychloroquine pills