What is Lichen Planus? Causes, Symptoms and Treatment

Lichen planus is a chronic, inflammatory skin condition that causes characteristic purple, flat-topped bumps that are often intensely itchy. While the condition is relatively common, it can be confusing for those experiencing it for the first time.

In this article we explain exactly what lichen planus is, how it looks, who gets it, and what treatment options are available.

What is lichen planus?

Lichen planus is a chronic, inflammatory skin condition thought to be an autoimmune reaction. This means the body's own immune system mistakenly attacks skin cells, triggering inflammation and the characteristic rash pattern.

The condition can affect the skin, oral mucosa, genitals, scalp and nails. Lichen planus is not contagious and cannot be spread to other people through physical contact.

Lichen planus is classified under ICD-11 as EA91. Treatment aims to relieve symptoms, as there is no cure.

What does lichen planus look like?

The classic sign of lichen planus is the "6 Ps":

Purple (Lilla): The colour is characteristically dark red to purple.
Polygonal (Polygonal): The bumps have irregular, flat-topped edges.
Papules (Papler): Small, raised bumps that may be solitary or form groups.
Pruritic (Kløende): Intense itching is one of the most prominent symptoms.
Planes (Fladtoppede): The surface is typically smooth and flat.

Another characteristic feature is Wickham striae — fine, white, lace-like lines on the surface of the bumps. These lines are often visible when the affected area is examined with a magnifying glass.

Lichen planus can also affect mucous membranes (especially the mouth), where it appears as white, lace-like patterns without typical itching. Nail involvement can cause ridges, thinning and in severe cases loss of the nail.

Why does lichen planus happen?

The exact cause of lichen planus is unknown, but various factors are thought to play a role in triggering the autoimmune reaction:

Autoimmune reaction

Research suggests that T-lymphocytes (a type of white blood cell) attack skin cells in an attempt to eliminate what it perceives as foreign — even though there is no actual foreign substance present.

Medications and chemicals

Certain medications can trigger lichen planus-like eruptions. Common culprits include blood pressure medications (ACE inhibitors), anti-inflammatory drugs, and some types of chemotherapy. Dental amalgam can trigger oral lichen planus.

Hepatitis C

There is a documented association between hepatitis C infection and lichen planus. Patients with oral lichen planus should be screened for hepatitis C.

Stress

Stress can worsen existing lichen planus and in some cases trigger the first outbreak. Stress management is an important part of treatment.

Who gets lichen planus?

Lichen planus affects up to 1–2% of the population worldwide:

Age: The condition occurs most frequently in adults between 30 and 60 years old.
Gender: Women are slightly more frequently affected than men, especially when it comes to oral lichen planus.
Genetics: A family history of lichen planus or other autoimmune diseases increases the risk.
Other diseases: People with hepatitis C, HIV or other autoimmune conditions have an elevated risk.

What can you do about lichen planus?

While there is no cure, lichen planus can often be managed with the right treatment. Treatment depends on severity and the affected body area:

💊 Topical corticosteroids

Corticosteroid creams and ointments are the first-line treatment for itching and inflammation. They reduce the immune response in the skin and relieve symptoms.

🩺 Calcineurin inhibitors

Creams with tacrolimus or pimecrolimus are often used on the face and mucous membranes, where steroids may be unsuitable.

💡 Light therapy (phototherapy)

Narrowband UVB light therapy can be effective for widespread lichen planus on the body.

💊 Oral retinoids

In severe or treatment-resistant cases, oral retinoids (isotretinoin) may be considered by a dermatologist.

🥗 Stress management and lifestyle

Since stress can worsen lichen planus, relaxation techniques, exercise and adequate sleep can help reduce flare-ups.

Medical classification: Lichen planus is classified as EA91 in the WHO's International Classification of Diseases (ICD-11). It is an inflammatory condition presenting with pruritic, purple, polygonal papules, often managed with topical steroids and oral retinoids.

Frequently asked questions

Is lichen planus dangerous?

Lichen planus is generally not dangerous, but oral lichen planus (in the mouth) carries a small risk of developing into oral cancer over time. Contact a doctor for mouth symptoms.

What are Wickham striae?

Wickham striae are the characteristic fine, white, lace-like lines visible on the surface of lichen planus bumps. They are named after the French dermatologist who first described them.

Can lichen planus go away on its own?

Mild lichen planus can spontaneously resolve within 1–2 years. Treatment speeds up relief and reduces the risk of complications such as scarring and nail changes.

When should I contact a dermatologist?

Contact a dermatologist if the rash is painful, affects your mouth or genitals, causes hair loss or nail changes, or does not improve with over-the-counter products.

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Disclaimer: This article is for informational purposes only and does not replace professional medical advice. Always consult a dermatologist for personal guidance.