As previously discussed, acne is caused by three things: (1) the P. acnes bacteria, (2) sebum and (3) dead skin cells (or dirt, etc.). Skin cells are produced deep in the basal (base) layer of the epidermis and rise towards the surface over time, die and are sloughed off. Note that sebum production is controlled by many, many factors (hormones, diet, genetics, etc.) which is part of the reason why it can be so difficult to figure out the "cause" of anyone's acne. Excess sebum/dead skin/dirt ---> results in bacteria flourishing ----> which results in inflammation and acne. Different types of medications target different parts of this process in order to prevent acne. Oral Antibiotics (Doxycycline, Monocycline, etc.) and Topical Antibiotics (Erythromycin, Clindamycin) Antibiotics will greatly decrease the presence of all bacteria. Note that bacteria is naturally-occurring and will return once you are no longer on antibiotics. Some antibiotics have been seen to induce resistance (so they stop working over time) Accutane targets sebum. It decreases oil production and reduces the size of the oil glands. It also slows down the production of skin cells and is anti-inflammatory (inflammation is an immune system response) AHAS come in a variety of forms and are water-soluble. AHAs include things like Glycolic acid (the smallest molecule of the AHAs), lactic acid, etc. BHAs comes in one form: Salycilic acid. It is oil-soluble. These acids softens the keratin (structural proteins) in the upper part of the skin (epidermis), which allows dead skin cells to exfoliate effectively. Retin-A based treatments promote exfoliation by increasing cell turnover which helps to prevent dead skin cells from getting trapped. Retinol is a less potent form of Retin-A. It is available in limited strengths as over-the-counter medicine whereas retin-as are not. Benzoyl Peroxide [*]BP is a topical medication that is toxic to the P. acnes bacteria. It has not been seen to induce bacteria resistance (so it will keep working over time). [*]BP is also anti-infammatory Birth Control/Hormonal Solutions [*]Birth control targets the production of sebum by normalizing your hormonal levels/activity; however, different types of birth control may be more or less effective at controlling it depending on your hormone levels
What is ACNE? Acne is the result of the sebum (oily substance produced by the skin's oil glands), P. acnes bacteria (which occurs naturally and lives off of sebum), and dead skin cells or dirt, etc. that get trapped in your pores. Overproduction of sebum and/or dead skin cells result in those things getting trapped by forrming a "plug" in your folicles, which causes the bacteria to flourish = infammation = acne. In properly functioning skin, the sebum should help to carry out dead skin cells, not trap them. What causes ACNE? Overproduction of sebum can be caused by a large number of health factors (stress, diet, medical condition, genetics, medicines, hormones, etc.) which is part of the reason why it is hard to know what exactly is "causing" your acne. Too many dead skin cells could be a result of not keeping your face clean or not exfoliating, etc. Irritation of the skin can also cause swelling which increases chances sebum will get trapped, etc. So there are many, many, many possible causes of acne. Which is why there is not a one-size-fits-all way to solve acne.