Medical Health Encyclopedia

It seems reasonable to assume that pustular psoriasis, which resembles an infection, is caused by some organism, but none to date have been identified.

Skin Injuries and the Köbner Response. The Köbner response is a delayed response to skin injuries, in which psoriasis develops later on at the site. In some cases, even mild abrasions can cause an eruption, which may be a factor in the frequency of psoriasis on the elbows or knees. (It should be noted that psoriasis can develop in areas with no history of skin disruption.)

Text Continues Below

---

Drugs. A number of drugs can worsen or induce pre-existing latent psoriasis, including the following:

• The anti-malarial drug chloroquine.
• Certain drugs used for hypertension and heart problems, including angiotensin-converting enzyme (ACE) inhibitors. Beta-blockers may actually trigger the onset of psoriasis and produce flare-ups in people who already have it.
• Progesterone used in female hormone therapies.
• Lithium, which is used in bipolar disorder. (It may trigger the onset of the disease and cause severe flare-ups in people who already have psoriasis.)
• Indomethacin, a non-steroidal anti-inflammatory drug (NSAID), can cause or worsen psoriasis. (Other NSAIDs, such as meclofenamate, may actually improve the condition.)
• Withdrawing from oral steroids or high-potency steroid ointments that cover wide skin areas can cause flare-ups of severe psoriasis, including guttate, pustular, and erythrodermic psoriasis. Because these drugs are also used to treat psoriasis, this rebound effect is of particular concern.
• Agents that cause rashes, a side effect of many drugs, can trigger psoriasis as part of the Köbner response.