The cause of pimples is unknown. The process by which a pimple develops is highly intricate. While we do know that a pore collapses on itself and blocks sebum (skin oil) from escaping, we do not fully understand why this process takes place in one sebaceous gland versus another.
Causes of Acne May Include:
Hormones. Acne is at least in part a hormonal disease. We know this because acne symptoms start only after adequate levels of hormones are present during puberty. Also, we know that acne symptoms usually increase when androgen (male hormone) levels increase. Increased levels of growth hormone and IGF-1 may also affect acne. Exactly how and why hormones affect acne remains unknown. More on hormones »
Diet. We do not know whether diet and acne are related. More research is required before anyone makes definitive claims. However, it is not yet time to discount the effect of diet on acne. More on diet »
Vitamin deficiency. Many of us have inadequate levels of vitamins and minerals in our bodies, especially vitamin D. How and if this affects acne is unknown. More on antioxidants »
Stress. The mind and the body are connected. This is not Eastern philosophy, it is undisputable physical reality. Emotional stress affects our endocrine (hormone) system, disgestive system, respiratory system, immune system, and various other bodily systems. Over-taxing the body through an overly demanding exercise schedule or lack of sleep may also cause physical stress, which can adversely affect our bodily processes. We know that both emotional and physical stress can aggravate acne, but exactly why remains a mystery. More on stress »
Evolutionary biology. Acne is a genetic disease. If your parents had acne, chances are you will as well. Why would evolution select for this trait? That is still unknown.
Inflammation. Acne pimples are often characterized by inflammation, which includes redness and soreness. Whether the body’s inflammatory response is a main cause of the acne formation process from the start or enters into the process more strongly once a pore is already clogged is the cause of debate. Most acne medications and treatments, including benzoyl peroxide, isotretinoin, retinoids, dapsone, and zinc have specific anti-inflammatory properties, which are thought to be partly responsible for their anti-acne action. Interestingly, evidence also points toward lower levels of anti-inflammatory antioxidants, such as vitamin A, vitamin E, and selenium, in the skin of people with acne. Furthermore, while results are still far from conclusive, some evidence is pointing toward a potentially beneficial effect from anti-inflammatory low glycemic diets, hinting toward systemic inflammation as a risk factor for acne.
And more... The real explanation could be a complex mix of the above factors, or some yet undiscovered cause may be uncovered. Acne remains one of medical science’s great unsolved mysteries. Why does it come about? Why does it subside in some people and not others? There are certainly many more questions than there are answers. Since we do not know what causes pimples, our time is better spent finding a tested and effective acne treatment.
Antibiotics have been a mainstay of acne treatment for decades, despite the fact that it is well known that they never completely clear acne and must always be administered alongside topical treatments.1-6They should only be used for a maximum of 3 months and thus, even when they do help reduce acne, offer only temporary relief. Oral antibiotics help kill acne bacteria (P. acnes) in people who are not resistant to their effects and also help reduce inflammation.7-10Topical antibiotics do not kill acne bacteria, but do help reduce inflammation.11Oral and topical antibiotics should never be used at the same time.
It has long been noted that antibiotics only work for about half of the population, and produce only moderate effectiveness.12When they do help, they often only work for a short period of time. Acne tends to "get used to" both oral and topical antibiotic treatments and becomes resistant to it.7,13It has become accepted practice that antibiotics must always be used in conjunction with other topical treatments because this helps reduce the chance for resistance, and because antibiotics do not work well enough on their own. As more research comes to light, it appears antibiotics are not helping clear acne as well as they once did. Researchers theorize this may be directly related to increased bacterial resistance across the population.13
A large study conducted by The British Journal of Dermatology studied 4274 acne patients and found that since 1991 an average of 51% of patients harbored colonies of resistant bacteria.14Other studies have shown similar levels of antibiotic resistant acne bacteria.15-24Interestingly, researchers are finding similar levels of resistance in both patients treated with antibiotics and those untreated as well, although those untreated have somewhat lower levels of resistance.25This is because it is quite easy to pass antibiotic resistant strains of bacteria to people close to you.26
How Resistance Happens
On a microscopic level, geneticists and biologists are finding multiple possible reasons why this occurs. The first reason is gene mutation within a bacteria cell.8,27-29Bacteria have also been observed banding together and producing biofilms, a coating which slows penetration of antibacterial medication.10
All antibiotics are well known to create resistant strains of bacteria, and these resistant strains of bacteria now colonize upwards of half of the population.30-31However, antibiotics have side effects beyond creating resistant bacteria. Oral antibiotics have more side effects than topical antibiotics and commonly cause gastrointestinal disorders (diarrhea, nausea, stomach cramps) and skin reactions. Depending on which antibiotic is prescribed, neurological problems (dizziness, vertigo) and photosensitivity (increased sensitivity to the sun) are also common. Less frequent side effects include permanent bluish-gray discoloration of the skin, permanent yellow/gray/brown discoloration of teeth, and sudden outbreaks of acne. In rare cases, oral antibiotics can cause auto-immune diseases (i.e. lupus), irreversible hearing loss, and heart problems which can lead to death.26,32-35
Topical antibiotics have fewer side effects but can also be absorbed through the skin and into the body and cause gastrointestinal problems. Upon application, topical antibiotics commonly cause peeling and skin irritation, including redness, dryness, and burning.26,32
Neither oral nor topical antibiotics should be used while attempting to become pregnant, while pregnant, or while breast feeding unless specifically directed by a physician.32
What to Do about It
First, if your doctor attempts to prescribe antibiotics for your acne, ask her why she wants you to do this and if there are other options you can try instead. If you are prescribed antibiotics from a doctor, do not stop your course before speaking with her about it since this can make it more likely that you will create resistant strains of bacteria that will be with you for the rest of your life.
Also keep in mind that benzoyl peroxide kills 99.9% of bacteria almost instantly and, when used correctly, will reliably and completely clear acne. It will never cause antibiotic resistance or the potential for systemic or long-term side effects and can be used for as long as you need to use it until you naturally grow out of acne.
If you have severe, widespread and deeply scarring acne, Accutane (isotretinoin) is also an option, but it comes with severe and potentially long-term side effects and must be entered into carefully alongside a trusted physician.
I took oral and/or topical antibiotics for a year or so altogether during high school and college, which is far longer than is prudent. Oral antibiotics did nothing for me and my skin did not improve, nor did it get worse, while on them. My skin worsened when I was put on clindamycin (clindamycin phosphate 1%), a topical antibiotic, but in retrospect this was likely because I stopped using benzoyl peroxide and instead started using clindamycin and sulfur, the two prescriptions my doctor wanted me to try. Antibiotics for me were like a bad joke—promising help but delivering nothing. It is more than likely that I now harbor colonies of resistant bacteria. Accutane cleared me up temporarily, but my acne returned post-Accutane. The Acne.org Regimen here at Acne.org finally got me cleared up for good."