The Koebner Phenomenon

What is the Koebner Phenomenon, and how does it affect those with psoriasis?

The Koebner Phenomenon is a reaction to skin injury often seen in psoriasis patients, and victims of some other diseases. After injury to the skin, new psoriasis plaques can flare up at the site of injury, or old ones spread. For this reason, it is important for psoriatics to avoid skin damage wherever possible.

The skin damage does not have to be severe. Like many other aspects of psoriasis, how badly a person will “Koebnerize” is a personal issue. Some people Koebnerize so easily that leaning on an elbow for too long or being chaffed by a car seat belt can turn the skin psoriatic in a matter of hours. Others don’t Koebnerize at all.

Better safe than sorry, though. Always be gentle to your skin. Pat dry after bathing, never rub. Don’t scrub or scrape excess flakes off. Avoid any sort of physical plaque removal, opt for long water soaks (which will cause the flakes to swell up and float away), or salicylic acid (unless you have bad reactions to that, of course). Sunburn has been known to cause wide-spread Koebnerization, as well, so be sure to use sunblock appropriately.

Low humidity can cause Koebner reactions also, but one of the keys to living easily with psoriasis is the appropriate use of moisturizers.

Some drugs (notably antimalarial drugs and lithium) can cause psoriasis to flare. Also, strep infections are a common trigger for widespread guttate psoriasis. Whether these fall under the umbrella of the Koebner phenomenon, I am unsure, but all psoriasis patients should be aware of them.