What is the Cobner phenomenon?

Koebner’s phenomenon (pronounced KOHB-nurs) is a skin disorder that occurs after skin trauma. The disease is named after the scientist Heinrich Kobner, who discovered it in 1876.

People with skin conditions such as psoriasis, vitiligo, and lichen planus often develop Cobner’s disease.

This article will help you understand what the Cobner phenomenon is, how to avoid it, and how to treat it, if any.

What is the Cobner phenomenon?

Koebner phenomenon (also called isomorphic reaction or Koebnerization) is a psoriatic rash that appears around wounds, such as cuts or burns. A rash can appear anywhere on the body where the skin has been traumatized.

Koebner’s phenomenon looks like raised skin lesions. Lesions tend to have the same characteristics as a person’s existing skin disease. Lesions usually follow the lesion line, and they may cover the entire skin lesion or develop in only one section.

Although Koebner’s phenomenon occurs after skin trauma, it is not an acute condition. Instead, it activates the underlying disease.

People with pre-existing skin conditions are most susceptible to Kobner’s phenomenon. For example, psoriasis patients experience Koebnerization 11% to 75% of the time, while vitiligo patients experience Koebnerization 21% to 62% of the time.

What Causes the Cobner Phenomenon?


Psoriasis is an autoimmune disease in which the body attacks normal skin cells. There are many types of psoriasis, and they all affect the body in different ways:

  • Plaque psoriasis is most common on the elbows, scalp, knees, and back. The lesions are red, raised, and scaly, and tend to crack, bleed, and itch.
  • Guttate psoriasis usually affects children and young adults. This condition is usually triggered by a viral or bacterial infection. The lesions are small, pink, tear-shaped, and scaly.
  • Reverse psoriasis is an uncommon type that tends to affect people who are overweight or obese. Lesions usually appear in skin folds such as the armpits, under the breasts, between the buttocks, in the skin folds of the genitals, or on the abdomen.
  • Pustular psoriasis develops pus-filled blisters that eventually become crusty plaques. It is usually triggered by certain medications or infections.
  • Scalp psoriasis can appear on the head, ears, and neck. The rash is red, thick, scaly and very itchy. Sometimes it can be mistaken for dandruff.
  • Nail psoriasis can cause the nail plate to sink or chip, and black, white, or yellow spots appear on the nail.
  • Erythrodermic psoriasis is a severe form of plaque psoriasis that affects the entire body and causes large patches of peeling skin. The condition can lead to dehydration and infection, which can be fatal if left untreated.
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Psoriasis flare-ups are usually triggered by medication, disease, or infection. While the exact cause of Koebner’s phenomenon remains unclear, it is believed that skin damage may trigger psoriasis flare-ups.

A 2011 study found that 28 percent of participants with psoriasis developed Koebner phenomenon after tattooing. Of the participants who developed Cobner’s disease, 30 percent reported flare-ups at the tattoo site between a week and twenty years after the tattoo. Less than 7% experienced emergencies elsewhere in the body.


Vitiligo is an autoimmune disease in which skin pigmentation disappears, resulting in smooth white patches on the body. People with vitiligo may also experience early graying and itching of the hair on the affected skin area.

Like psoriasis, vitiligo has certain triggers, including stress, sunburn, chemicals, and viruses. Skin damage may also trigger Koebnerization.

What causes vitiligo?

Studies have shown that vitiligo is more likely to occur when vitiligo covers a larger body surface area and when there is greater disease activity.

Lichen planus

Lichen planus is an autoimmune disease that causes a purple, itchy rash. This condition can affect many parts of the body, including the inside of the mouth.

Koebner’s phenomenon is thought to be the activation of an underlying disease, and lichen planus is an autoimmune disease that may trigger it.


The exact cause of the Kobner phenomenon is unknown. However, theory suggests that it is triggered by an abnormal immune response (ie, it is immune-mediated).

Additionally, some experts believe that both the epidermis and dermis of the skin must be damaged to trigger the condition.

Real and fake Koebner’s responses

A true Koebner reaction occurs with pre-existing autoimmune diseases that affect the skin. A pseudo-Kobner reaction is when an infection such as a viral wart or molluscum contagiosum spreads the lesions to the injured skin.

If a person has an existing autoimmune disease, Koebner’s can be caused by damaged skin. Examples of trauma that can lead to the Cobner phenomenon include:

  • animal or insect bites
  • sunburn or other burns
  • friction (including shaving)
  • reduce
  • freezing
  • pressure
  • tattoo
  • some vaccines
  • Tuberculosis test
  • iodine

A limited number of case studies suggest that Koebner’s phenomenon may occur in people without pre-existing autoimmune skin conditions. However, overall research suggests that the condition is strongly associated with autoimmune diseases that affect the skin, such as psoriasis, vitiligo, and lichen planus.

Body modification

Tattoos and piercings may contribute to Koebner phenomenon in people with autoimmune skin diseases because tattoos and piercings, while adornment and beautifying the body, can also damage the skin (a risk factor for Koebner phenomenon).

While body modification increases your risk of Koebner’s phenomenon if you have psoriasis, vitiligo, or lichen planus, it’s important to also consider the value of a potential tattoo or piercing.

In a Koebner study on tattoos, 82% of participants said their tattoos had a positive effect on their body image. The study concluded that tattoos should not be a contraindication for patients with psoriasis, but should receive appropriate prior counseling.

Can you get a tattoo if you have psoriasis?

see a dermatologist

If you notice changes in your skin, make an appointment with a dermatologist. If you notice damage to your skin—especially if you have an autoimmune disorder like psoriasis—a dermatologist will be able to screen for and treat Koebner’s phenomenon.

Koebner’s phenomenon is diagnosed by looking at lesions that behave in the same way as a person’s pre-existing skin condition. A dermatologist will also rule out an infection or allergic reaction.

If Koebner’s disease is diagnosed, treatment usually includes systemic therapy for psoriasis to suppress Koebner’s phenomenon or topical creams, lotions, and ointments (both over-the-counter and prescription) to cover the lesions.

Skin care for psoriasis flare-ups

Psoriasis flare-ups can be caused by many factors, including stress, skin trauma, dry skin, medications, alcohol, and infections.

When you experience flare-ups, your dermatologist may prescribe medications to calm and heal your skin:

  • Topical medications such as steroid creams, non-steroid creams, and over-the-counter (OTC) creams, shampoos, and soaps to heal and soothe the skin
  • phototherapy (phototherapy), which uses ultraviolet light to slow the growth of affected skin cells
  • Systemic injectable or oral medications for use throughout the body
  • Diet and lifestyle changes, including maintaining a healthy weight for you and trying to reduce stress

What causes a psoriasis flare-up?

You can usually treat mild flares at home. The National Psoriasis Foundation recommends using:

  • aloe vera
  • Diluted apple cider vinegar
  • Dead Sea salt in a warm bath
  • Oatmeal paste or oatmeal bath (for itching)
  • tea tree oil
  • Turmeric in supplement form

Always ask your doctor or dermatologist about any home remedies you are considering. This way, you can be sure they are safe for you and will not interfere with your treatment plan or medications.

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Frequently Asked Questions

What does the Cobner phenomenon look like?

The appearance of Koebner’s phenomenon depends on a person’s autoimmune status. Koebner’s phenomena tend to behave in the same way as preexisting conditions.

For example, if a person has psoriasis, Koebner’s can appear as a raised, itchy, flaky rash that spreads over the skin lesions.

What is an isomorphic response?

Isomorphic response is another term for Koebner’s phenomenon. Isomorphism is the Greek word for “isomorphism”. This phrase is used because Koebner’s lesions are the same as a person’s underlying condition.

How to prevent psoriasis flare-ups?

Psoriasis tends to flare up if a person experiences specific triggers. Everyone’s triggers are different. Common triggers include stress, skin trauma, dry skin, drugs, alcohol, and infections.

It’s important to identify things that predispose to psoriasis and avoid them, but it can take some detective work. A symptom diary can help you figure out what’s causing your flare-up.

11 Medications That Can Trigger Psoriasis

VigorTip words

If you have psoriasis or other skin autoimmune diseases, you may be at increased risk of developing Koebner’s phenomenon.

If your skin is injured, including tattoos and piercings, pay close attention to your injured area for damage. Contact your doctor or dermatologist if any changes occur.

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