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Psoriasis Triggers

Environmental Factors that Trigger Psoriasis


Updated May 16, 2014

Psoriasis is a complicated, chronic skin disorder. We are still struggling to understand what goes on at the molecular level in this frustrating disease. Psoriasis is caused by one or more mutations in certain genes that then trigger cells in the immune system to attack the skin. But not everyone with these mutations gets psoriasis. The following are environmental factors that can trigger a psoriasis flare.

Skin Injury

Sometimes an injury to the skin can cause the formation of a psoriasis patch. This is known as the Koebner Phenomenon, and it can occur in other skin diseases, such as eczema and lichen planus. It can take 2 to 6 weeks for a psoriasis lesion to develop after an injury. Types of injuries that can trigger a flare include:
  • Abrasion - even mild abrasion
  • Increased friction from clothing or skin rubbing against skin in folds, such as armpits or under breasts
  • Sunburn
  • Viral rashes
  • Drug rashes


Weather is a strong factor in triggering psoriasis. Exposure to direct sunlight, which usually occurs in the warmer months, often improves the rash. On the other hand, cold, short days seen in the winter months can trigger the rash to worsen.


Psychological stress has long been understood as a trigger for psoriasis flares, but scientists are still unclear about exactly how this occurs. Studies do show that not only can a sudden, stressful event trigger a rash to worsen, daily hassles of life can also trigger a flare. In addition, one study showed that people who were categorized as "high worriers" were almost two times less likely to respond to treatment compared to "low worriers."


Infections caused by bacteria or viruses can cause a psoriasis flare. Streptococcal infections that cause tonsillitis, or strep throat, tooth abscesses, cellulitis, and impetigo can cause a flare of guttate psoriasis in children. The human immunodeficiency virus (HIV) does not increase the frequency of psoriasis, but it does increase the severity of the disease.

Low Vitamins

Low levels of calcium have been reported as a trigger for psoriasis. Oddly enough, even though medications made from vitamin D are used to treat psoriasis, low levels of vitamin D do not trigger a flare-up.

Drug Triggers

The following drugs are known to either worsen psoriasis or induce a flare-up:
  • Chloroquine -- used to treat or prevent malaria
  • ACE inhibitors -- used to treat high blood pressure. Examples include monopril, captopril, and lisinopril.
  • Beta blockers - also used to treat high blood pressure. Examples include lopressor and atenolol.
  • Lithium -- a medication used to treat bipolar disorder
  • Indocin -- an anti-inflammatory medication used to treat a variety of conditions, including gout and arthritis
  • Corticosteroids, such as prednisone or solumedrol, can actually dramatically improve psoriasis. However, abruptly stopping the drug or rapidly tapering off of it can trigger a flare-up.


Fortune, Donal, et al. "Psychologic Factors in Psoriasis: Consequences, Mechanisms, and Interventions." Dermatologic Clinics 23(2005): 681-94.

Habif, Thomas. "Psoriasis." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 209-39.

Schon, Michael, and W.-Henning Boehncke. "Psoriasis." The New England Journal of Medicine 352(2005): 1899-912.

Smith, Catherine, and JNWN Barker. "Psoriasis and its management." British Medical Journal 333(2006): 380-4.

van de Kerkhof, Peter. "Psoriasis." Dermatology. Ed. Jean Bolognia. New York: Mosby, 2003: 531-5. 125-37

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