Well-identified triggers include Injury (Koebner phenomenon) Sunburn HIV infection Beta-hemolytic streptococcal infection (leading to guttate psoriasis) Drugs (especially beta-blockers, chloroquine, lithium, angiotensin-converting enzyme inhibitors, indomethacin, terbinafine, and interferon-alfa) Emotional stress Alcohol consumption Tobacco smoking Obesity Symptoms and Signs of Psoriasis Lesions are either asymptomatic or pruritic and are most often localized on the scalp, extensor surfaces of the elbows and knees, sacrum, buttocks (commonly the gluteal cleft), and genitals.