There is no specific scientific evidence linking masturbation and acne. However, for hundreds if not thousands of years, societies around the world, in an attempt to prevent young people from engaging in premarital sex, have latched onto the myth that sex/masturbation and acne are in some way related. Let's take a moment now to look at modern science and see if we can help unravel this controversy.
There are no published studies attempting to link masturbation or sex with acne. Until researchers produce those studies, we'll need to take a step back. We do know that hormones and acne are linked, particularly when it comes to increased levels of androgens (male hormones) such as testosterone. So let's look at how arousal and the sex act affect hormone levels. First, it's worth mentioning that we know far more on this topic when it comes to animals such as rats and monkeys than we do about humans.1-4 Science is spotty in the area of human hormonal production and sex. According to a study in the journal Psychosomatic Medicine, "...small differences in methodology and data interpretation may easily produce contrasting results."5 A survey of the evidence bears this out.
Several studies show very small increases in testosterone after orgasm in both men and women, while others show statistically insignificant differences.5-8 Studies specific to arousal show from very small increases in hormone levels to insignificant changes.5-6,8 However, even when changes are apparent, levels return back to baseline within minutes. As you can see, we have little if any compelling evidence. To complicate matters even more, a study in the Journal of Zhejiang University SCIENCE in 2003 showed a marked increase in testosterone on the 7th day of abstinence, which the authors posit is possibly due to sperm formation and maturation.9
We simply do not know whether masturbation or sex is related to acne, or for that matter human hormonal balance. Current research tends to point toward very small hormonal changes after arousal or sex, if any. Whether these changes are beneficial or detrimental for acne remains unknown.