The natural, anti-inflammatory compounds of seaweed have positive effects when treating acne. According to the American Academy of Dermatology, acne is caused by release of sebum, or oils, which prevents the skin from becoming dry. Pimples are inflammations of the skin pores, which traps the oil, resulting in blackheads or whiteheads, deeper pimples, or cystic acne. Seaweed's anti-inflammatory effect reduces swelling of the skin. It can also be used as a natural exfoliant to remove dead skin cells which block pores.