Forehead pimples can be caused by various factors, including the use of certain hair products, hormonal changes, stress, and skin irritation. When the pores in the skin become clogged with dead skin cells and oil, acne develops. Bacteria called Propionibacterium acnes also play a role in inflammation, which results in the red bumps that characterize acne. Forehead acne often looks like solid red bumps, called papules, and can be treated with good skin care, such as washing the face twice a day with a gentle cleanser and using OTC acne cream that contains ingredients like benzoyl peroxide or salicylic acid. It is also important to avoid touching the face frequently, removing makeup before going to bed, and using noncomedogenic haircare products to prevent acne from forming around the hairline