Acne is the most common skin disorder seen by doctors. In fact, it will affect almost every one of us at some time in our lives. It can happen at any time, but teenagers are the ones who are affected more often.
Acne can cause a great deal of embarrassment and anxiety. If it’s severe it can cause people to become depressed which can lead to withdrawing from friends, and performing poorly at school or work.
What Causes Acne?
The exact cause of acne is unknown, but is the visible end result of hormonal, bacterial and inflammatory disturbances that take place at the level of the oil pore (pilosebaceous follicle).
Three Main Events Result in Pimple Formation.
1. Excess oil production plus dead skin cells plug pores.
Acne starts when the hair follicles become plugged with oil and dead skin cells. Each follicle is connected to sebaceous glands. These glands secrete an oily substance known as sebum to lubricate your hair and skin. Sebum normally travels up along the hair shafts and then out through the opening of the hair follicle onto the surface of your skin. When your body produces an excess amount of sebum and dead skin cells, the two can build up in the hair follicle and form together as a soft plug. This plug may cause the follicle wall to bulge and produce a whitehead. Or, the plug may be open to the surface and may darken, causing a blackhead. For the majority of acne sufferers, the excess sebum production begins at puberty, when the body begins to produce hormones called androgens (in boys this is primarily testosterone). These hormones cause the sebaceous glands to enlarge, which is a natural part of the body’s development. In acne sufferers, however, the sebaceous glands are overstimulated by androgens, sometimes well into adulthood. Androgens are also responsible for acne flare-ups associated with the menstrual cycle and, on occasion, pregnancy.
2. Bacteria within clogged pores multiply and secrete toxins that trigger inflammation.
When the pore becomes blocked, the bacteria living within it use the oil as a food source and divide rapidly. The particular bacteria that is involved in acne is called Propionibacterium acnes, (P. acnes for short) and is a regular resident of all skin types; it’s part of the skin’s natural sebum maintenance system. Once a follicle is plugged, however, P. acnes bacteria multiply rapidly, and produce a variety of chemical compounds that are secreted. These chemical compounds signal the immune system to recruit white blood cells and re-direct them from the circulation into the pore to fight the bacteria. This process of white blood cell recruitment is called “chemotaxis”.
3. Immune cells enter pore to kill bacteria, causing inflammation and swelling.
When white blood cells enter the pore they multiply and secrete a variety of enzymes, and other inflammatory hormones that help fight the bacterial infection. However, the inflammatory hormones, enzymes, and other chemicals that immune cells produce cause the skin to become inflamed and red. The blocked pore swells with cells and fluid, and the end result is a visible, red, painful pimple. The inflammatory response is different for everyone, but studies have shown that it is especially strong in adult women. The inflammatory response by immune cells in the pore causes an abnormal production of collagen. Typically, collagen production decreases causing depressed scarring (“pockmarks”). Occasionally, this can be followed by increased collagen production, resulting in thickening of these scars.
How Can Acne be Treated?
There are many topical OTC products available to treat acne. Many contain benzoyl peroxide which arrests bacterial growth, but cannot open plugged pores to release trapped bacteria. The other common "active" ingredient for acne treatment products is Salicylic Acid, which, because it is an oil soluble acid, can help unblock pores, thus allowing the P acnes to escape and by doing so reduce the inflammation caused by the bacteria. Salicylic acid is derived from Willow Bark, and many studies over the past 60 years have suggested that salicylic acid may also have mild anti-inflammatory effects.
Stronger prescription products that are used to treat acne include antibiotics and retinoic acid derivatives. Antibiotics help reduce P.acne levels and recent studies show that they may also have anti-inflammatory effects. Retinoids are thought to reduce sebum production thus reducing the frequency of plugged pores. However, retinoids have some potential side effects and should be used only under a physician's care.