Acne scars are caused by inflammation within the dermal layer of skin and are estimated to affect 95% of people with acne vulgaris.[31] The scar is created by abnormal healing following this dermal inflammation.[32] Scarring is most likely to take place with severe acne, but may occur with any form of acne vulgaris.[31] Acne scars are classified based on whether the abnormal healing response following dermal inflammation leads to excess collagen deposition or loss at the site of the acne lesion.[33]
Acne mechanica is caused by heat, friction, and pressure against the skin, often the result of wearing sports gear such as a helmet or baseball cap. It is sometimes called "sports-induced acne" because it occurs frequently in athletes. Preventive measures include wearing an absorbent material under sports equipment and showering immediately after activity.
Inflammatory Acne: Inflammatory acne is red bumps and pustules, not whiteheads, blackheads and comedones. It doesn't necessarily start as them, either. It arises on its own. Whiteheads, blackheads or comedones that become inflamed can be painful and unsightly. Persistent inflammatory acne may require treatment by a physician or dermatologist, in addition to over-the-counter acne remedies.
Combination therapy—using medications of different classes together, each with a different mechanism of action—has been demonstrated to be a more efficacious approach to acne treatment than monotherapy.[10][47] The use of topical benzoyl peroxide and antibiotics together has been shown to be more effective than antibiotics alone.[10] Similarly, using a topical retinoid with an antibiotic clears acne lesions faster than the use of antibiotics alone.[10] Frequently used combinations include the following: antibiotic and benzoyl peroxide, antibiotic and topical retinoid, or topical retinoid and benzoyl peroxide.[47] The pairing of benzoyl peroxide with a retinoid is preferred over the combination of a topical antibiotic with a retinoid since both regimens are effective but benzoyl peroxide does not lead to antibiotic resistance.[10]

Medical conditions that commonly cause a high-androgen state, such as polycystic ovary syndrome, congenital adrenal hyperplasia, and androgen-secreting tumors, can cause acne in affected individuals.[45][46] Conversely, people who lack androgenic hormones or are insensitive to the effects of androgens rarely have acne.[45] An increase in androgen and oily sebum synthesis may be seen during pregnancy.[46][47] Acne can be a side effect of testosterone replacement therapy or of anabolic steroid use.[1][48] Over-the-counter bodybuilding and dietary supplements are commonly found to contain illegally added anabolic steroids.[1][49]


Your pimples need TLC, too. The study on acne vulgaris found that, in an attempt to dry out acne lesions, patients often use too many products or apply excessive amounts to problem areas, resulting in further irritation and over drying of the skin. Vigorous scrubbing and using harsh exfoliants can make acne worse by rupturing whiteheads and blackheads, turning them into painful red ones. And remember: no matter how satisfying it is, picking and popping your zits will also increase inflammation and opportunity for infection.

The Anti-Redness Exfoliating Solution is mostly water, but its 2 percent salicylic acid is enough to eat through oil and remove the dead skin cells clogging your pores — and it boasts a higher concentration than nearly every other kit we looked at. Sodium hyaluronate, the super-moisturizing humectant we fell in love with in our review on the Best Face Moisturizer, also caught our eye sitting smack dab in the middle of the ingredients list.
Antibiotics. These work by killing excess skin bacteria and reducing redness. For the first few months of treatment, you may use both a retinoid and an antibiotic, with the antibiotic applied in the morning and the retinoid in the evening. The antibiotics are often combined with benzoyl peroxide to reduce the likelihood of developing antibiotic resistance. Examples include clindamycin with benzoyl peroxide (Benzaclin, Duac, Acanya) and erythromycin with benzoyl peroxide (Benzamycin). Topical antibiotics alone aren't recommended.
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