What is the characteristic sign of acne?

The characteristic sign of acne is the presence of pustules and cysts. These are formed due to the clogging of hair follicles with excess oil, dead skin cells, and bacteria. Pustules are small, inflamed lesions filled with pus, while cysts are larger, painful bumps that can occur deeper in the skin. The formation of these types of lesions is a direct result of the inflammatory process associated with acne, indicating that the body is responding to blocked pores and bacterial growth.

While flaking skin, redness, and irritation, as well as dry patches, can be associated with various skin conditions, they do not specifically denote acne. Flaking skin might occur in conditions like eczema or dry skin, while redness and irritation can be present in numerous skin disorders. Dry patches typically indicate skin dehydration rather than the characteristic lesions of acne. Thus, the presence of pustules and cysts is the defining feature of acne, distinguishing it from other skin conditions.