C. acnes also provokes skin inflammation by altering the fatty composition of oily sebum.[45] Oxidation of the lipid squalene by C. acnes is of particular importance. Squalene oxidation activates NF-κB (a protein complex) and consequently increases IL-1α levels.[45] Additionally, squalene oxidation leads to increased activity of the 5-lipoxygenase enzyme responsible for conversion of arachidonic acid to leukotriene B4 (LTB4).[45] LTB4 promotes skin inflammation by acting on the peroxisome proliferator-activated receptor alpha (PPARα) protein.[45] PPARα increases activity of activator protein 1 (AP-1) and NF-κB, thereby leading to the recruitment of inflammatory T cells.[45] The inflammatory properties of C. acnes can be further explained by the bacterium's ability to convert sebum triglycerides to pro-inflammatory free fatty acids via secretion of the enzyme lipase.[45] These free fatty acids spur production of cathelicidin, HBD1, and HBD2, thus leading to further inflammation.[45]


Acne conglobata is one of the most severe forms of acne. It involves many inflamed nodules that are connected under the skin to other nodules. It can affect the neck, chest, arms, and buttocks. It often leaves scars. This type of acne is more common in men and is sometimes caused by taking steroids or testosterone. Timely treatment by a dermatologist is essential.
The side effects depend on the type of treatment you use. Generally, for topical, over-the-counter creams, you can watch out for stinging, redness, irritation and peeling — these side effects usually don’t go any deeper than the skin. Others, like oral antibiotics or hormonal medications, could come with new sets of complications, so we suggest talking to your doctor before pursuing the treatment.

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.
Eat healthily. Foods that are highly processed and contain a lot of oils greatly increase the amount of acne on your body. Getting the proper amount of nutrients from whole grains, fruits, vegetables, and protein help your skin to regenerate faster and limit unnecessary oil production. When at all possible, avoid foods that are processed or contain a lot of sugar (think junk foods).[11]
Baby acne almost always goes away on its own with no intervention. But bring it to your pediatrician's attention if the bumps look like they might be infected (for example, skin appears extra red, you notice swelling or discharge, or your child spikes a fever or has other symptoms) or if you suspect an allergic reaction or eczema (which may require a cream to keep the rash from spreading).
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.
Light therapy is a treatment method that involves delivering certain specific wavelengths of light to an area of skin affected by acne. Both regular and laser light have been used. The evidence for light therapy as a treatment for acne is weak and inconclusive.[8][139] Various light therapies appear to provide a short-term benefit, but data for long-term outcomes, and for outcomes in those with severe acne, are sparse;[140] it may have a role for individuals whose acne has been resistant to topical medications.[10] A 2016 meta-analysis was unable to conclude whether light therapies were more beneficial than placebo or no treatment, nor how long potential benefits lasted.[141] PDT has the most supporting evidence of all light therapies.[77]
“Sometimes I see people try over-the-counter products just for a couple of weeks, they get frustrated, they say it’s not working, and they discontinue them,” Arthur says. “But it really does take a while to see the effectiveness. So unless you’re having a problem with the medication, like it’s causing severe irritation or dryness, it’s recommended to give it at least 2-3 months before switching to something else.”
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Acne vulgaris Acne conglobata Acne miliaris necrotica Tropical acne Infantile acne/Neonatal acne Excoriated acne Acne fulminans Acne medicamentosa (e.g., steroid acne) Halogen acne Iododerma Bromoderma Chloracne Oil acne Tar acne Acne cosmetica Occupational acne Acne aestivalis Acne keloidalis nuchae Acne mechanica Acne with facial edema Pomade acne Acne necrotica Blackhead Lupus miliaris disseminatus faciei
Retinoids and retinoid-like drugs. These come as creams, gels and lotions. Retinoid drugs are derived from vitamin A and include tretinoin (Avita, Retin-A, others), adapalene (Differin) and tazarotene (Tazorac, Avage). You apply this medication in the evening, beginning with three times a week, then daily as your skin becomes used to it. It works by preventing plugging of the hair follicles.
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