Psoriasis vs Lichen Planus: Key Differences

October 13, 2026

Psoriasis and lichen planus are both non-infectious, itchy skin conditions linked to the immune system, which is why they are often confused. The quickest clues: psoriasis usually forms thick, raised plaques with dry, silvery-white scale on the elbows, knees, scalp and lower back, while lichen planus forms small, shiny, flat-topped bumps that look purple, grey or brown, often on the inner wrists, ankles and shins, and it can also show up as lacy white lines inside the mouth. A dermatologist can usually tell them apart by looking, and sometimes with a small skin biopsy.

If you are new to psoriasis, start with our guide to what psoriasis is and its different types.

Key takeaways

Neither psoriasis nor lichen planus is contagious. You cannot catch either one or pass it on through touch, food or shared towels.
Psoriasis: raised plaques with silvery-white scale, commonly on the scalp, elbows, knees and lower back. Nails may show tiny pits.
Lichen planus: shiny, flat-topped bumps that are purple or violet on lighter skin and grey or brown on darker skin, often with fine white lines on top. It favours the wrists, ankles, shins and the inside of the mouth.
Skin lichen planus often settles on its own within months to a couple of years. Psoriasis is usually long-term and comes and goes in flares.
A sore in the mouth that does not heal, scarring hair loss, or nails that are thinning and splitting are reasons to see a doctor soon.

Why psoriasis and lichen planus get mixed up

Both conditions are driven by the immune system rather than by germs. Both can itch, both can appear on the skin, scalp and nails, and both can flare where the skin has been scratched or injured, which doctors call the Koebner phenomenon.

In India there is an extra layer of confusion. On brown skin, the classic "pink plaque" of psoriasis can look dark red, violet or brown, and the classic "purple bump" of lichen planus can look grey or brown. So the colour clues in Western textbooks are less reliable here, and the shape, scale and location of the rash matter more.

The NHS also lists eczema, ringworm and pityriasis rosea as look-alikes. See our guide on psoriasis vs eczema if that is your question.

Side-by-side: how they usually look

Feature	Psoriasis (plaque type)	Lichen planus (skin)
Shape	Thick, raised patches (plaques), from coin-sized to large	Small, flat-topped, shiny bumps that can join into patches
Surface	Dry, silvery-white scale that flakes off	Shiny; may have fine white lacy lines (Wickham striae); little loose scale
Colour on Indian skin	Red, dark red, violet or brown, with whitish scale	Purple, grey or brown
Common sites	Scalp, elbows, knees, lower back	Inner wrists, ankles, shins, lower back; inside the mouth
Mouth	Rarely affected	Often affected: lacy white lines or painful sores
Nails	Tiny pits, discolouration, crumbling, lifting	Thinning, ridges, splitting, sometimes a scar at the cuticle (pterygium) or nail loss
Scalp	Thick scale; hair usually grows back once settled	Lichen planopilaris can cause permanent bald patches
Usual course	Long-term, with flares and calmer periods	Skin form often settles in about 9 to 18 months; mouth form can last years

These are typical patterns, not rules. Some people have features of both, and thick (hypertrophic) lichen planus on the shins can look very much like psoriasis.

Where each condition appears on the body

Psoriasis

The American Academy of Dermatology (AAD) says plaques usually appear on the scalp, elbows, knees or lower back, but can develop anywhere, including skin folds, palms and soles.

Lichen planus

The AAD describes lichen planus bumps most often on the inside of the wrists, arms, legs or lower back. Small bumps can merge into larger patches, usually on the shins and ankles.

The biggest difference is the mouth. Lichen planus often causes lacy white lines or small white spots on the inner cheeks and tongue, and sometimes painful sores on the gums. Spicy, sour or very hot food can sting. Psoriasis rarely does this. A skin rash plus white patches inside the cheeks points more towards lichen planus.

Scalp, nails and hair: the clues that matter most

Nails

Psoriasis typically causes small dents called nail pits, discolouration, crumbling or lifting. See our guide to nail psoriasis.

In lichen planus, DermNet notes that about 10% of people have nail involvement. Nails may become thin, ridged and split, and sometimes a small scar grows from the cuticle onto the nail (called a pterygium). Nails can occasionally be lost permanently, so early care matters.

Scalp and hair

Scalp psoriasis causes thick, scaly patches. Any hair shedding is usually temporary. Lichen planus on the scalp, called lichen planopilaris, is different: it can destroy hair follicles and leave permanent bald patches.

Causes, triggers and the hepatitis C question in India

Psoriasis runs in families and flares with stress, throat infections, skin injury, smoking, alcohol and some medicines. Lichen planus has no single known cause. The AAD says the immune system seems to attack healthy tissue, and anything that irritates the affected area can cause a flare.

Some medicines can cause a lichen planus-like rash, called a lichenoid drug eruption. DermNet lists gold, hydroxychloroquine and captopril among the common culprits, and quinine and thiazide water tablets (diuretics) as causes of a sun-related form.

DermNet lists hepatitis C as a possible contributing factor, but Indian data have not shown a clear link. A 2006 case-control study from Kolkata, published in the Indian Journal of Dermatology, Venereology and Leprology, found only 2 of 104 lichen planus patients positive for hepatitis C antibodies, and concluded that hepatitis C "is not significant to the causation of LP in India". A 2017 study of 84 patients at a tertiary centre in Kerala found none positive for hepatitis B or C.

How doctors tell them apart, and how each is treated

Most of the time a dermatologist can tell the two apart by examining the skin, nails, scalp and inside of the mouth. When the picture is unclear, a small punch biopsy under local anaesthetic gives a clear answer, because the two look quite different under the microscope. Read how psoriasis is diagnosed to know what to expect.

Treatment overlaps but is not the same, which is why the correct diagnosis matters:

Lichen planus: not always treated, as the skin form can settle on its own. Doctors may use potent steroid or calcineurin inhibitor creams, steroid injections into thick patches, mouth gels, and for widespread disease, steroid tablets or phototherapy.
Psoriasis: usually longer-term care with steroid and vitamin D creams, phototherapy, methotrexate or biologics for moderate to severe disease.

Steroids, phototherapy and biologics all have a real place when used under a doctor's supervision. The problem in India is unsupervised use of over-the-counter steroid creams and mixed "triple" creams, which can thin the skin and make both conditions harder to manage. Please do not stop or change a prescribed treatment without speaking to your doctor.

Gentle daily care for itchy, dry skin

Whichever condition you have, these habits help protect the skin barrier:

Bathe in lukewarm water, not hot. The NHS suggests avoiding soap on affected skin; a mild, fragrance-light cleanser is kinder.
Moisturise within a few minutes of bathing, while skin is still slightly damp, and again at night. This helps with dryness and itching.
Try not to scratch or pick. Both conditions can spread to scratched skin. Keep nails short and try a cool, damp cloth when itching peaks.
For mouth lichen planus, avoid tobacco, gutkha, paan and alcohol, and go easy on very spicy, sour or salty food if it stings.

You can also browse our itching and dryness range, which includes steroid-free Ayurvedic creams and oils that may help soothe dry, itchy skin as part of your daily routine. They are skincare, not a replacement for a doctor's treatment.

Safety notes on herbal products: some Ayurvedic skin products contain babchi (bakuchi) oil, which can make skin more sensitive to sunlight, so avoid strong sun on treated areas and stop if you notice burning or blistering. Do not apply herbal oils to open mouth sores or broken genital skin. In pregnancy, breastfeeding or for children, check with a doctor first, and always patch-test. Giloy has been linked to liver injury in some reports, so avoid herbal tablets without medical advice.

When to see a doctor

See a dermatologist for any new rash that does not settle within two to three weeks, so the right diagnosis is made early. Go sooner if you notice:

A mouth sore or patch that does not heal in two to three weeks, that thickens, hardens or bleeds, or that makes swallowing painful. Long-standing erosive lichen planus in the mouth carries a small increased risk of oral cancer, especially with tobacco or alcohol use.
Patchy hair loss with tender, burning or red bumps on the scalp.
Nails that are thinning, splitting, shedding or have stopped growing.
Painful sores, burning or white patches on the genitals.
Swollen, painful finger or toe joints, heel pain or morning stiffness alongside skin patches (a possible sign of psoriatic arthritis).
Red, inflamed skin covering most of the body, with fever, chills or feeling unwell. This needs same-day medical care.

Frequently asked questions

Can lichen planus turn into psoriasis?

No. They are separate conditions. Rarely, a person can have both, and a few rashes show features of each, which is why a biopsy is sometimes needed.

Is lichen planus contagious?

No. The AAD and NHS both state that you cannot catch lichen planus from someone else or pass it on. The same is true for psoriasis.

Which is more serious, psoriasis or lichen planus?

It depends on the person. Skin lichen planus often settles within a couple of years, but mouth, scalp and nail forms can be long-lasting and need closer follow-up. Psoriasis is usually long-term and linked to joint and heart health.

Why are my lichen planus spots turning dark brown?

As lichen planus settles, it often leaves grey-brown marks, especially on Indian skin. DermNet notes these can take a year or longer to fade. Gentle care and sun protection help; harsh scrubbing does not.

Sources

This article is for general information and is not medical advice. Please consult a qualified dermatologist or Ayurvedic doctor for diagnosis and treatment.

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