The signs and symptoms of lichen planus vary depending on the areas affected. Typical signs and symptoms include:
- Purplish, flat-topped bumps, most often on the inner forearm, wrist or ankle, but sometimes on the external genitals
- Blisters that may break to form scabs or crusts
- Lacy white patches in the mouth — inside the cheeks or on the gums, lips or tongue
- Painful oral or vaginal ulcers
- Hair loss and scalp discoloration
- Nail damage or loss
When to see a doctor
See your doctor if tiny bumps or a rash-like condition appears on your skin for no apparent reason, such as a known allergic reaction or contact with poison ivy. Also see your doctor if you experience any signs or symptoms associated with lichen planus of the mouth, genitals, scalp or nails.
It's best to get a prompt and accurate diagnosis because a number of skin and mucosal conditions can cause lesions and discomfort.
Lichen planus occurs when your immune system mistakenly attacks cells of the skin or mucous membranes. No one knows the exact cause of this abnormal immune response. The condition isn't contagious.
In some people, certain factors, such as those below, may trigger lichen planus.
- Hepatitis C infection
- Flu vaccine
- Certain pigments, chemicals and metals
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil, Motrin IB, others) and naproxen (Aleve, others)
- Certain medications for heart disease, high blood pressure or arthritis
Anyone can develop lichen planus. But the condition most often affects middle-aged adults.
Lichen planus can be difficult to manage on the vulva and in the vagina, causing severe pain and sometimes leaving scars. Sexual dysfunction can become a long-term complication.
There is some evidence that lichen planus may increase your risk of a skin cancer known as squamous cell carcinoma, though the risk is small. Your doctor may recommend routine screening for evidence of cancerous cells in tissues affected by lichen planus.
For many people the affected skin might stay slightly darker even after the rash clears up.