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]
Although the late stages of pregnancy are associated with an increase in sebaceous gland activity in the skin, pregnancy has not been reliably associated with worsened acne severity.[137] In general, topically applied medications are considered the first-line approach to acne treatment during pregnancy, as they have little systemic absorption and are therefore unlikely to harm a developing fetus.[137] Highly recommended therapies include topically applied benzoyl peroxide (category C) and azelaic acid (category B).[137] Salicylic acid carries a category C safety rating due to higher systemic absorption (9–25%), and an association between the use of anti-inflammatory medications in the third trimester and adverse effects to the developing fetus including too little amniotic fluid in the uterus and early closure of the babies' ductus arteriosus blood vessel.[47][137] Prolonged use of salicylic acid over significant areas of the skin or under occlusive dressings is not recommended as these methods increase systemic absorption and the potential for fetal harm.[137] Tretinoin (category C) and adapalene (category C) are very poorly absorbed, but certain studies have suggested teratogenic effects in the first trimester.[137] Due to persistent safety concerns, topical retinoids are not recommended for use during pregnancy.[138] In studies examining the effects of topical retinoids during pregnancy, fetal harm has not been seen in the second and third trimesters.[137] Retinoids contraindicated for use during pregnancy include the topical retinoid tazarotene, and oral retinoids isotretinoin and acitretin (all category X).[137] Spironolactone is relatively contraindicated for use during pregnancy due to its antiandrogen effects.[1] Finasteride is not recommended as it is highly teratogenic.[1]
Your skin is your largest organ, and it does a lot more than simply prevent you from spilling out all over the place. Skin cells are constantly replacing themselves, making a journey from the inner edge of your epidermis (your skin's outermost layer) to the outside of your skin. As a skin cell ages and approaches the skin's surface, the dying cell flattens out. Once on the surface, it joins countless other dead skin cells and forms a protective layer that helps protect you from bacteria and viruses.

Any acne treatment is a weeks-long experiment that you’re conducting with your skin. Acne is slow to heal, and in some cases, it can get worse before it gets better (nearly every benzoyl peroxide product we looked at emphasized the likeliness of irritating acne further, and starting off with a lighter application). April W. Armstrong, a doctor at the University of California Davis Health System, recommends waiting at least one month before you deem a product ineffective.
Comedones associated with acne vulgaris are usually easy to clear using OTC products, but papules and pustules are a little tougher to treat. Since they arise from trapped, infected pores, the first step in their treatment is to remove the inflammation and reduce the swelling so the pore can heal and breathe. Nodules are one of the few acne conditions that actually demand treatment, as some risk the potential of becoming cancerous. Medical treatment with traditional antibiotic therapy will relieve the symptoms of your acne nodule and gradually decrease its size.

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]


There are a number of mild chemical peels available over the counter, but acne scar removal requires a stronger peel typically administered by a doctor or dermatologist. Trichloroacetic acid (TCA) peels are slightly stronger than alpha hydroxy acid (AHA) peels and may be used for acne scar treatment. The strongest type, phenol peels, may cause significant swelling and require up to two weeks of recovery time at home. Neither are recommended for people with active severe acne.
Castor oil has anti-inflammatory and antibacterial properties that can speed up healing, making it ideal for breakout-prone skin. Though I recommend using it in very small amounts with jojoba oil, hemp seed oil or coconut oil, along with one of the essential oils above, it’s high in unsaturated fatty acids, vitamin E, proteins and minerals, which can help reduce acne-causing bacteria and inflammation associated with breakouts. It can even help heal scars caused by acne.
This inflammatory cascade typically leads to the formation of inflammatory acne lesions, including papules, infected pustules, or nodules.[1] If the inflammatory reaction is severe, the follicle can break into the deeper layers of the dermis and subcutaneous tissue and cause the formation of deep nodules.[1][66][67] Involvement of AP-1 in the aforementioned inflammatory cascade leads to activation of matrix metalloproteinases, which contribute to local tissue destruction and scar formation.[45]
^ Jump up to: a b c Zaenglein, AL; Graber, EM; Thiboutot, DM (2012). "Chapter 80 Acne Vulgaris and Acneiform Eruptions". In Goldsmith, Lowell A.; Katz, Stephen I.; Gilchrest, Barbara A.; Paller, Amy S.; Lefell, David J.; Wolff, Klaus (eds.). Fitzpatrick's Dermatology in General Medicine (8th ed.). New York: McGraw-Hill. pp. 897–917. ISBN 978-0-07-171755-7.
Pimples are raised red spots with a white center that develop when blocked hair follicles become inflamed or infected with bacteria. Blockages and inflammation that develop deep inside hair follicles produce cystlike lumps beneath the surface of your skin. Other pores in your skin, which are the openings of the sweat glands, aren't usually involved in acne.
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