Causes and Triggers

Psoriasis is not contagious.

You cannot catch it from anyone.

One thing is certain:


While scientists do not know what exactly causes psoriasis, we do know the immune system, and genetics play key roles. The genetics of psoriasis are complex, and it is possible to develop psoriasis even if you have no family history of the disease. A triggering event may cause a change in the immune system, resulting in the onset of psoriasis symptoms. Common triggers for psoriasis include stress, illness (particularly strep infections), injury to the skin, and certain medications.


Psoriasis triggers vary from person to person. What may worsen your psoriasis might not have any impact on someone else. Common psoriasis triggers include:


Stress is one of the most common psoriasis triggers. At the same time, a psoriasis flare can cause stress. This may seem like an endless loop. However, relaxation techniques and stress management may help prevent stress from impacting psoriasis.

Injury to Skin

Psoriasis can appear in areas of the skin that have been injured or harmed. This is a result of the Koebner [KEB-ner] phenomenon, where scratches, sunburns, bug bites, and vaccinations can all trigger psoriasis flares.

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Anything that can affect the immune system can trigger psoriasis. That is why you may experience a flare following an ear infection, bronchitis, tonsillitis, or respiratory infection. There is a connection between streptococcus infection (strep throat) and guttate psoriasis, as it often triggers the first onset of guttate psoriasis in children.

It is possible to have strep throat without showing symptoms. If you have had strep throat in the past, talk with your health care provider about getting a strep throat test if your psoriasis flares.


The weather may trigger a flare. Cold weather can often cause psoriasis flares due to less sunlight and humidity, heated and drier indoor air, as well as stress and illness. Warm weather can often improve psoriasis because of natural sunlight and higher humidity.

Other Possible Triggers

Although it is less common, some people with psoriasis suspect that allergies, certain foods, alcohol, or environmental factors trigger their psoriasis. A great way to learn about your unique set of triggers is to track them over time. Keeping records of your symptoms and triggers can help you anticipate and treat your flares.

Track Your Flares

Track your skin and joint symptoms and learn more about potential triggers for your psoriatic disease.

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Last updated on 12/21/2022 by the National Psoriasis Foundation.

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