Although a genetic disease, psoriasis is heavily influenced by the environment the person grows up and lives in. One individual may carry the tendency but never express the disease but could pass it onto children who could express it. Psoriasis tends to fluctuate in its intensity and then settles at a particular level. In some people this is very minor, only affecting the knees or elbows. Psoriasis will tend to improve in most patients in sunlight and we often use artificial sunlight to treat patients with psoriasis.
Some patients get worse in the sun.
Infections such as cold, flu and sore throats can make psoriasis worse and may induce a guttate episode, where multiple small areas of psoriasis occur on the body. Psoriasis may improve or worsen during pregnancy. If it improved during pregnancy it may become much worse after pregnancy. A number of drugs can make psoriasis worse - lithium used in depression and aspirin. Psoriasis may settle quickly when taking steroids tablets but if the steroids are stopped suddenly, the psoriasis may flare up very badly.