The rash often seems to start after some sort of trigger factor. These factors should be avoided whenever possible by people with psoriasis. There are probably others that we haven't discovered yet. It is not due to any particular food so special diets are not helpful, unless excessive weight is making psoriasis of the skin creases more troublesome. Moderate alcohol intake doesn't affect it, although it may interfere with certain treatments.
Excessive alcohol aggravates psoriasis.
Psoriasis is not an allergy, nor is it infectious to others. Psoriasis may improve or get worse during pregnancy. It does not have any harmful effect on either mother or child. Although the predisposition to psoriasis may pass on to the affected person's children, this does not necessarily mean they will develop the rash. The extent of psoriasis varies, and fluctuates even without treatment.