Why is my forehead breaking out with acne suddenly? Is it diet? Is it stress?

FOREHEAD ACNE. Forehead acne can be due to a number of things: greasy, oily conditioners; oily shampoos; hats and caps, not shamooing often enough, hairsprays, gels, other new hair cosmetics. Some medications also. Eating nuts and chocolate. Anything new in your diet? If it persists, see a dermatologist.