Acne is a very common skin problem that we see every day. Our children may be severely affected leading to social fears. Women may have it and this can be more distressing to older patients. Acne has many factors driving it. The problem begins in the hair follicle and sweat gland complex, known as the pilosebaceous unit. Even if don't see the hairs they are there. Basically there are three issues to mention.

  1. Sebaceous gland overactivity- the sebaeous glands produce sebum and secrete it onto the skin through the hair follicle pore. The sebaceous glands are all over the body, but more are on the face, back shoulders and chest. These glands become more active during puberty. Some hormones may make the glands produce more sebum. There is just more sebum being produced than can be secreted out of the gland.

    In males, testosterone drives the sebum production. In females, the increase in hormone, LH, following ovulation increases sebum production. Women will have breakouts 2 to 7 days prior to menstruation due to this. Altered hormone conditions such as PCOS will also contribute to acne.

    Sebum seems to be responsible for the inflammation in acne. More. Linoleic acid is interesting-more later.

  2. Follicle keratin changes-just as the skin cells change and die and must be sloughed off, so it is in the hair follicle "tube". The hair follicle "tube" is lined with cells which mature and die and need to come out of the follicle. In acne, these cells, called keratinocytes are sticky and clump together. They cause the formation of Comedones- or blackheads (when the pore is open) and Whiteheads (when the pore is closed). The clogged pore with all of this sebum is now a feast for bacteria including acnes bacteria.

    The body then mounts a battle (immune response) to the bacteria which leads to the redness, pus, and typical "pimple."

  3. Bacteria involvement- the acne bacteria (Propionibacterium acnes is the scientific name) are also on normal faces so why don't we all have acne. The bacteria probably cause problems in acne as a result of their digestive enzymes leading to the production of Free Fatty Acids from the breakdown of Triglycerides. This FFA and other agents probably cause much of this inflammation. As was mentioned above the acne patients make much more sebum than do others, so more sebum means more FFA from bacterial digestion.

hair follicle diagram

Types of lesions

A hair follicle, which is plugged and full of sebum and acne bacteria is the primary lesion. This swollen follicle is a "whitehead" when it is under the skin and the "blackhead" when it is on the surface. Other lesions are papules -small, red, bumps; pustules- small, red bumps with pus; nodules- large, round, painful, lumps deeper in the skin; cysts- bigger deeper bumps that cause scaring.


Most treatments just target future lesions and so they take up to eight weeks to work. Salicylic Acid, Benzoyl Peroxide, and Steroids will treat lesions that you see now. Steroids are problem as they can cause another type of acne.
There are 5 goals to treating acne:

  1. Normalize skin cell growth. The skin cells, which we will call k-cytes, mature through the skin and need to slough off the skin surface as well as out of the hair follicles. These cells stick together in acne and form clumps which keeps the sebum from coming out of the gland. Retinoids have affects on these cells which keep them from being sticky and can loosen the clogs in the pore. They also decrease how much sebum the gland makes.

  2. Work against acne bacteria. Antibiotics, benzoyl peroxide attacks the bacteria and stops chemicals of inflammation. the antibiotics fight the bacteria and also decrease FFA's produced when the bacteria digests lipids on the skin. Lots of the bacteria are resistant to antibiotics. Benzoyl peroxide makes a reactive oxygen molecule that kills bacteria. the problem is that this oxygen molecule can cause early aging of the skin. The other problem is that benzoyl peroxide can destroy retinoids like tretinoin, which is also used for acne.

  3. Remove the pore clog. BHA can loosen k-cytes that are plugging the hair follicle. Salicylic acid is better at reducing the number of comedones than AHA.

  4. Attack inflammation. Salicylic acid can stop the inflammation in acne NSAIDs such as Ibuprofen along with antibiotics can decrease the number of acne lesions.

  5. Decrease sebum production. Retinoids decrease sebaceous gland activity. Hormone adjustments with oral contraceptives can decrease sebaceous gland activity also.