Acne is one of the most common skin disorders in the U.S. with over 60 million Americans affected. Eighty-five percent of all teenagers suffer from acne, but this disorder is not limited to adolescents. Approximately 20% of adults have acne as well. Acne affects men and women of all races and skin types. It typically starts at an early age--as young as ten years old--and usually goes away on its own by the late teens or early 20’s. For some people, their first bout of acne is in adulthood. Although there are exceptions, acne tends to occur earlier in females and last longer, while males may have a later onset but more severe course. Genetics play an important role in determining one’s individual experience with acne.
Three main factors contribute to the formation of acne: androgenic hormones, plugging of the hair follicle, and bacteria. It is not surprising that acne first develops during puberty when hormone levels, particularly androgens, are circulating at high levels. Androgenic hormones stimulate sebaceous glands to enlarge and increase sebum production. The excess sebum joins the sticky debris from dead skin cells to clog hair follicles which then leads to the formation of comedones. The clogged follicle is a friendly environment for the bacteria Propionibacterium acnes (P. acnes). These bacteria break down the lipids found in sebum into free fatty acids which are thought to be irritating to the skin, resulting in inflammation. P. acnes also attract neutrophils, white blood cells that play a role in fighting infection, to the site of the clogged follicle. In addition to these causative factors, many factors may aggravate acne. These include: stress, fluctuating hormone levels (for instance, in pregnancy), certain medications, and ingredients found in skin products.
There are two major categories of acne: non-inflammatory and inflammatory. The non-inflammatory lesions are either closed comedones (“whiteheads”) or open comedones (“blackheads”). Closed comedones are small, flesh-colored or slightly red bumps that are caused by follicles containing a plug of sebum and keratinous debris. The pore is closed or small and difficult to see. In contrast, open comedones appear black on the surface of the skin because the pore is open and distended which makes the plug visible. The exposed black surface of the plug is caused by the skin’s natural dark pigment melanin and should not be confused with dirt. In inflammatory acne, comedones develop in the same way as in non-inflammatory acne, but they then become infected with bacteria which triggers an inflammatory response by the body’s immune system. As white blood cells swarm to the infected area, the comedone swells to produce a larger bump called a papule that can be tender. As more inflammation occurs, pus accumulates at the surface of the skin to form a pustule. The most severe inflammatory acne causes nodules and “cystic” lesions which can be very prominent, painful, and permanently scarring.
Certain medications can cause or aggravate acne. Several of these include anabolic steroids, lithium, anti- seizure medications, and iodinated substances. “Steroid acne” is an acne- like skin condition caused by oral or topical corticosteroids. It usually disappears once the medication is discontinued. Do not discontinue medications prescribed for medical illnesses on your own, but instead ask your physician for options that may be less prone to aggravating your acne.
Reviewed by: Michael Fuller, MD