Injury to the skin can cause the formation of a psoriasis patch 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 and rashes.resulting from a reaction to medication.
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.
Stress plays a major role in all skin conditions. Stress can trigger a 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.
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 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.