Lichen Planus: Symptoms, Causes, and How It's Treated

You noticed a cluster of small, purplish, intensely itchy bumps on your wrists or ankles, and they don't look like anything you've had before. It's unsettling, especially when they seem to spread and won't go away. What you may be dealing with is lichen planus, a fairly common inflammatory skin condition that is not contagious, not cancer, and in most cases settles down on its own with time and the right care.

Here is the short answer to what most people are searching for: lichen planus is a chronic, T-cell mediated inflammatory condition that produces itchy, flat-topped purple bumps on the skin and can also affect the mouth, nails, scalp, and genitals. It affects roughly 1% of people worldwide, usually adults aged 30 to 60. There is no cure, but treatments reliably calm the itch and inflammation, and most skin cases clear within one to two years.

What is lichen planus?

Lichen planus is an inflammatory condition in which your immune system's T-cells mistakenly attack cells in your skin or the lining of your mouth and other mucous surfaces. It is considered an autoimmune disorder, and while it can be uncomfortable and persistent, it is not contagious and you cannot catch it or pass it to anyone else.

Dermatologists describe the classic skin presentation using the '6 Ps': purple, polygonal (many-sided), planar (flat-topped), pruritic (itchy), papules and plaques. The bumps have a shiny surface, often crossed by fine white lines called Wickham striae. They show up most often on the wrists, lower back, and ankles. The condition affects women slightly more often than men, at roughly a 1.5 to 1 ratio.

What does lichen planus look like, and where does it appear?

Lichen planus can affect more than just the skin. Knowing the different forms helps explain why symptoms vary so much from person to person.

• Skin: shiny, firm, flat-topped bumps that are red, purple, or violet and usually itchy, often with fine white lines (Wickham striae) on top.
• Mouth (oral lichen planus): lacy white patches or red, swollen tissue and open sores on the inner cheeks, gums, or tongue, sometimes with burning or pain. About 50% of people with lichen planus have oral involvement.
• Nails: thinning, ridging, splitting, or even nail loss. Around 10% of people have nail changes.
• Scalp (lichen planopilaris): redness and irritation that can lead to permanent hair loss if untreated.
• Genitals: soreness, burning, and lacy white lines on the vulva, vagina, or penis.
• Koebner effect: new bumps can appear along scratch marks or surgical scars where the skin has been injured.

What causes lichen planus?

In most cases, the exact cause is unknown. What is understood is the mechanism: immune T-cells attack a protein in the skin or mucous membranes, driving the inflammation. It is not caused by poor hygiene, an infection you caught, or anything you did wrong.

Certain triggers have been linked to lichen planus or to look-alike reactions. These include some medications used for high blood pressure, diabetes, heart disease, and malaria, which can prompt a lichenoid drug reaction. Skin injury can also set off new lesions in someone already prone to the condition. Because the triggers vary, it is worth telling your clinician about every medication and supplement you take.

How long does lichen planus last?

For most people with skin involvement, lichen planus is self-limiting. The lesions tend to clear on their own within one to two years of onset. After the bumps fade, they commonly leave behind flat brown or gray marks called post-inflammatory hyperpigmentation, which can take many months to lighten.

Lichen planus affecting the mouth, genitals, nails, or scalp tends to be more long-lasting and may need ongoing management. Recurrences are common across all types, so even after a clear stretch, new flares can happen. An asymptomatic case confirmed by biopsy may need no treatment at all, just monitoring.

How is lichen planus treated?

There is no cure, so treatment focuses on relieving itching and inflammation and shortening flares. A dermatologist tailors the plan to where your lichen planus is and how severe it is, because no single approach works best for everyone. This is general education, not a treatment plan for your individual case, so do not start or stop any prescription on your own.

• Topical or oral corticosteroids to reduce inflammation, the usual first-line approach.
• Calcineurin inhibitors such as tacrolimus ointment or pimecrolimus cream, often used for the mouth and sensitive areas.
• Antihistamines to help control the itch.
• Phototherapy (controlled UV light) for widespread skin disease.
• Reviewing your medications in case a drug is contributing to a lichenoid reaction.

When should you see a doctor?

See a clinician if you have new, spreading, intensely itchy bumps, or any of the mouth, nail, scalp, or genital symptoms above. Lichen planus is diagnosed by a skin exam and often a small biopsy, and getting the right diagnosis matters because several conditions can look similar.

Oral lichen planus deserves ongoing monitoring. A large systematic review of 6,559 patients found that 92 developed oral squamous cell carcinoma, an overall malignant transformation rate of 1.40% and an annual rate of about 0.20%. That risk is low but real, which is why dermatologists and dentists keep an eye on persistent mouth lesions. Get prompt care for any non-healing sore, a growing or changing patch, scalp lesions with hair loss, or severe pain, since early treatment protects against scarring and catches problems sooner.