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]
Many skin conditions can mimic acne vulgaris, and these are collectively known as acneiform eruptions.[28] Such conditions include angiofibromas, epidermal cysts, flat warts, folliculitis, keratosis pilaris, milia, perioral dermatitis, and rosacea, among others.[20][72] Age is one factor which may help distinguish between these disorders. Skin disorders such as perioral dermatitis and keratosis pilaris can appear similar to acne but tend to occur more frequently in childhood, whereas rosacea tends to occur more frequently in older adults.[20] Facial redness triggered by heat or the consumption of alcohol or spicy food is suggestive of rosacea.[73] The presence of comedones helps health professionals differentiate acne from skin disorders that are similar in appearance.[8] Chloracne, due to exposure to certain chemicals, may look very similar to acne vulgaris.[74]
What to know about hormonal imbalances While it is natural to experience hormonal imbalances at certain times in life, such as puberty, menopause, and pregnancy, some hormonal changes are related to underlying medical conditions. This article looks at the causes and symptoms of hormonal imbalances in men and women, as well as treatment and home remedies. Read now
Hypertrophic scars are uncommon, and are characterized by increased collagen content after the abnormal healing response.[32] They are described as firm and raised from the skin.[32][34] Hypertrophic scars remain within the original margins of the wound, whereas keloid scars can form scar tissue outside of these borders.[32] Keloid scars from acne occur more often in men and people with darker skin, and usually occur on the trunk of the body.[32]
If your baby still has acne at 3- to 6-months-old, infantile acne may be the culprit. “These bumps tend to be more red and inflammatory,” says Dr. Kahn. “You’ll see more of the different types of acne than with baby acne, including pustules and cysts, not just whiteheads and blackheads.” And unlike baby acne, infantile acne is linked to family history: Your baby is more likely to get it if you or your partner had severe acne as a teen. Acne in older babies can also be an indication that your baby is more likely to have acne later in life. Like baby acne, infantile acne rarely needs treatment; if there’s a lot of redness and swelling, however, your doctor might want to treat it with a topical antibiotic.
The recognition and characterization of acne progressed in 1776 when Josef Plenck (an Austrian physician) published a book that proposed the novel concept of classifying skin diseases by their elementary (initial) lesions.[163] In 1808 the English dermatologist Robert Willan refined Plenck's work by providing the first detailed descriptions of several skin disorders using a morphologic terminology that remains in use today.[163] Thomas Bateman continued and expanded on Robert Willan's work as his student and provided the first descriptions and illustrations of acne accepted as accurate by modern dermatologists.[163] Erasmus Wilson, in 1842, was the first to make the distinction between acne vulgaris and rosacea.[164] The first professional medical monograph dedicated entirely to acne was written by Lucius Duncan Bulkley and published in New York in 1885.[165][166]
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.
Oh, hello old friend. Salicylic acid is the go-to fix for pimply preteens. And cruising through the aisles at the drugstore, you’ll find it as the active ingredient on the majority of products labeled “acne wash” or “spot treatment.” Salicylic acid is a beta-hydroxy acid that works by dissolving excess oil and gently exfoliating away dead skin cells. Salicylic also has anti-inflammatory properties to help with inflamed cystic breakouts that can occur when blockages deep in the hair follicles rupture beneath the skin. It’s best to apply this ingredient as a toner, moisturizer, or leave-on spot treatment instead of a face wash to give it time to do its work. And keep in mind, salicylic acid can dry out the skin if over-applied, so maybe choose only one product with the ingredient to use every day.
Risk factors for the development of acne, other than genetics, have not been conclusively identified. Possible secondary contributors include hormones, infections, diet and stress. Studies investigating the impact of smoking on the incidence and severity of acne have been inconclusive.[2][38][39] Sunlight and cleanliness are not associated with acne.[14]

In 2015, acne was estimated to affect 633 million people globally, making it the 8th most common disease worldwide.[9][18] Acne commonly occurs in adolescence and affects an estimated 80–90% of teenagers in the Western world.[19][20][21] Lower rates are reported in some rural societies.[21][22] Children and adults may also be affected before and after puberty.[23] Although acne becomes less common in adulthood, it persists in nearly half of affected people into their twenties and thirties and a smaller group continue to have difficulties into their forties.[2]
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.