To many parents’ dismay, their beautiful newborn’s face breaks out with red bumps at around 3 to 4 weeks of age. This is called baby acne. It tends to occur at about the same age as the baby’s peak gas production and fussiness. How attractive! (This all coincides with parents’ maximum sleep deprivation.) Parents are often quite concerned both about how these bumps look and about their significance.

It is widely suspected that the anaerobic bacterial species Cutibacterium acnes (formerly Propionibacterium. acnes) contributes to the development of acne, but its exact role is not well understood.[2] There are specific sub-strains of C. acnes associated with normal skin, and moderate or severe inflammatory acne.[50] It is unclear whether these undesirable strains evolve on-site or are acquired, or possibly both depending on the person. These strains have the capability of changing, perpetuating, or adapting to the abnormal cycle of inflammation, oil production, and inadequate sloughing of dead skin cells from acne pores. Infection with the parasitic mite Demodex is associated with the development of acne.[30][51] It is unclear whether eradication of the mite improves acne.[51]

A major mechanism of acne-related skin inflammation is mediated by C. acnes's ability to bind and activate a class of immune system receptors known as toll-like receptors (TLRs), especially TLR2 and TLR4.[45][64][65] Activation of TLR2 and TLR4 by C. acnes leads to increased secretion of IL-1α, IL-8, and TNF-α.[45] Release of these inflammatory signals attracts various immune cells to the hair follicle including neutrophils, macrophages, and Th1 cells.[45] IL-1α stimulates increased skin cell activity and reproduction, which in turn fuels comedo development.[45] Furthermore, sebaceous gland cells produce more antimicrobial peptides, such as HBD1 and HBD2, in response to binding of TLR2 and TLR4.[45]
Keep in mind that even if some products market themselves toward severe acne breakouts, all the kits we looked at are definitely designed for mild to moderate acne. Not sure if you fit on that scale? You’re not alone! When you’re in the middle of a breakout, all acne seems severe, so it can be difficult to self-diagnose your symptoms. We talked to dermatologists and cosmetic chemists to better understand the differences between the various types of acne (see below).
Salicylic acid and azelaic acid. Azelaic acid is a naturally occurring acid found in whole-grain cereals and animal products. It has antibacterial properties. A 20 percent azelaic acid cream seems to be as effective as many conventional acne treatments when used twice a day for at least four weeks. It's even more effective when used in combination with erythromycin. Prescription azelaic acid (Azelex, Finacea) is an option during pregnancy and while breast-feeding. Side effects include skin discoloration and minor skin irritation.
Salicylic acid is a topically applied beta-hydroxy acid that stops bacteria from reproducing and has keratolytic properties.[131][132] It opens obstructed skin pores and promotes shedding of epithelial skin cells.[131] Salicylic acid is known to be less effective than retinoid therapy.[20] Dry skin is the most commonly seen side effect with topical application, though darkening of the skin has been observed in individuals with darker skin types.[1]
Misperceptions about acne's causative and aggravating factors are common, and those affected by it are often blamed for their condition.[176] Such blame can worsen the affected person's sense of self-esteem.[176] Until the 20th century, even among dermatologists, the list of causes was believed to include excessive sexual thoughts and masturbation.[165] Dermatology's association with sexually transmitted infections, especially syphilis, contributed to the stigma.[165]

Acne medications work by reducing oil production, speeding up skin cell turnover, fighting bacterial infection or reducing inflammation — which helps prevent scarring. With most prescription acne drugs, you may not see results for four to eight weeks, and your skin may get worse before it gets better. It can take many months or years for your acne to clear up completely.