In this blog, I explored the connection between stress and acne, and in this blog, I investigated the link between diet and acne. Now, I want to take a look at another factor that could potentially affect acne: smoking.

The first study I came across used a questionnaire to determine if there was a correlation between smoking and acne. Researchers controlled for gender differences, and came to the conclusion that there was no association between acne and smoking cigarettes. Thus, the evidence presented in this study is consistent with the null hypothesis that there is no relationship between these two factors. We know that the results of this study must be either correct or a false negative.

However, in continuing to investigate, I found a study that contradicted the evidence presented in the first study. This study found a “significant linear relationship between acne prevalence and number of cigarettes smoked daily.” Thus, the conclusions made were that “smoking is a clinically important contributory factor to acne prevalence and severity.” This study was a cross-sectional study, so the evidence presented here is neither more nor less convincing than that of the original study. In addition, it is true that a confounding variable could be causing the association found in this study. Such a variable might be proneness to stress, which could be causing someone to both smoke cigarettes and suffer from worsened acne. Even so, the evidence found in this study is consistent with the alternative hypothesis that there is a relationship between smoking and acne. Thus, the results of this study must be either correct or a false positive.

A third study resulted in evidence in support of a completely different hypothesis altogether. The conclusions of this cross-sectional study suggest that overall, “acne sufferers were less likely to smoke.” When it came to gender differences, researchers found that “daily cigarette consumption” was likely to hinder acne development in girls, while there were no such associations found when it came to boys. Thus, researchers involved in this study are arguing that, in fact, smoking lessens the prevalence of acne in girls. We must also keep in mind that a confounding variable could be behind this association. Such a variable might be, for example, high socioeconomic status, since someone with this privilege has sufficient money to spend on both cigarettes and skincare products (which would account for tendency to both smoke and have less acne).

When comparing all of these studies, it is clear that they present conflicting evidence. Unfortunately, based on the evidence from these three studies alone, we cannot conclude anything about the relationship between smoking and acne. Perhaps a meta-analysis of several studies done exploring this relationship might reveal which side of the argument has more evidence supporting it. Until that is done, however, we cannot be sure which of the arguments to agree with. But, one thing we know for sure (as Andrew has reviewed this in class) is that smoking has negative health benefits. Therefore, I suggest that we leave the cigarettes alone, because, in any case, they will certainly do more harm than good.

(As a side note, this blog is part of a three-part series in which I explore possible factors affecting of acne. You can find Part 1 here and Part 2 here).