Azelaic acid has been shown to be effective for mild to moderate acne when applied topically at a 20% concentration.[66][129] Treatment twice daily for six months is necessary, and is as effective as topical benzoyl peroxide 5%, isotretinoin 0.05%, and erythromycin 2%.[130] Azelaic acid is thought to be an effective acne treatment due to its ability to reduce skin cell accumulation in the follicle, and its antibacterial and anti-inflammatory properties.[66] It has a slight skin-lightening effect due to its ability to inhibit melanin synthesis, and is therefore useful in treating of individuals with acne who are also affected by postinflammatory hyperpigmentation.[1] Azelaic acid may cause skin irritation but is otherwise very safe.[131] It is less effective and more expensive than retinoids.[1]
A nodule is an abnormal tissue growth which can either develop just below the skin or anywhere within the skin’s three layers (the epidermis, dermis, and subcutaneous tissue). Nodules commonly form in regions such as the face, neck, armpits, and groin, although they can also develop on internal organs such as the lungs, thyroid, and lymph nodes. They create solid, raised lumps that are more than 1 to 2 centimeters in diameter, with the potential to reach up to the size of a hazelnut. Nodules are hard and firm to the touch, unlike cysts whose pus makes them softer to the touch. This type of severe acne should be consulted by a doctor, as it might be indicative of a more serious condition.
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]
From the What to Expect editorial team and Heidi Murkoff, author of What to Expect the First Year. Health information on this site is based on peer-reviewed medical journals and highly respected health organizations and institutions including ACOG (American College of Obstetricians and Gynecologists), CDC (Centers for Disease Control and Prevention) and AAP (American Academy of Pediatrics), as well as the What to Expect books by Heidi Murkoff.
We suggest avoiding spot treatments. “Benzoyl peroxide, when placed on red spots, can actually cause more irritation and inflammation to the area. It’s best used to prevent red bumps and pustules, and applied all over the area you want to treat,” said Townsend, who was also quick to naysay a spot-treat-only approach: “Acne affects all of the pores. If someone is going to spot treat against my advice, I still suggest they spot treat one day and treat the whole face the next.”
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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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