I don't know why but I guess it depends how dry. Cracking, peeling face can cause a lot of irritation. But a little flaking on areas where there is acne could help speed up the healing process

massive amounts of BP without moisturiser might clear your acne but skin will look patchy and dry without being moisturised, what is the benefit of that? If dry skin is good result to you then there is no point to have any discussion about it really.

I don't know why but I guess it depends how dry. Cracking, peeling face can cause a lot of irritation. But a little flaking on areas where there is acne could help speed up the healing process

How do you know that a dry environment "irritates" the acne to grow? I would think that bacteria would prefer a wet enviornment over a dry one.

Nobody wanna take a shot at this?

Hmm, I'll take a shot...

So when I think about acne and its causes in relation to my own skin, I tend to divide it betwen hormones, bacterial environment, and sebum environment. I think of these differently, and that seems to work for me. So for instance, when I'm ovulating or premenstrual, or when I'm very stressed out, my hormonal environment is strange and my skin will respond very uncharacteristically: unpredictable cystic acne, any picking leads to way worse consequences than otherwise, and so on. In terms of bacterial environment, I think of this in relation to frequency and efficacy of face washing, and whether I touch my skin a lot.

I think the sebum environment is what we're talking about here: BP is great for killing the bacterial environment. But don't forget: sebum isn't exactly wetness, and I'm not sure you can think of your skin bacteria the same way as you think of mold. Scientists have demonstrated a significant correlation between sebum environment and acne, though they're still not entirely sure whether excess sebum excretion causes acne or not. In fact, as the Beauty Brains recently discussed (they're great cuz they look at academic dermatology in their research), they're not really sure when or why your skin decides it needs more sebum.

I think that when people say that drying treatments are bad, though, they're not necessarily talking about sebum environments. We actually don't know if the skin has external mechanisms for regulating its sebum excretion. By this I mean, your skin could just be secreting sebum based on a cocktail of factors we don't yet understand, but that it might not have anything to do with how moist, oily, or dry your skin already is. And excess sebum might not actually result in more acne, although it probably does in the case of comedone acne.

So what we're really talking about here is irritation. It is irritating for your skin to be excessively dry, in the same way that it's irritating to put harsh chemicals on it. Does this aggravate acne somehow? And if so, how? I've been playing around on Google Scholar and taking advantage of my institutional access to peer-reviewed journals to try to figure the link out. Does dry skin lead to irritation? What is skin irritation? Inflammation? Does the inflammation encourage the production of acne? Or does it somehow create a good bacterial environment for acne?

Well, let me tell you, this is a really hard question to answer! From what I can tell though, I think people might caution against anything that leads to skin irritation, including dryness, because it can result in an immune response - inflammation. Acne is characterized as being both a bacterial problem and, to some extent, an immunologic problem. So to me, the logic almost seems like this: you want to avoid irritating the skin for the same reason that you might want to avoid eating pine nuts if you're allergic to peanuts. If your body is exhibiting an oversensitive immune response that leads to an undesirable physical problem (like your throat swelling up or acne), then avoid things your body might mistake for whatever is causing that immune overresponse. In the case of acne, dermatologists seem to agree that this means we should avoid irritating the skin, just in case your body's production of acne is an immunologic response as well as a bacterial or sebacious (sebum) problem. This means they counsel that patients avoid harsh chemical treatments, overwashing, or overdrying the skin unnecessarily.

You see, you need to remember that with BP, it's not the drying that's helping your skin. BP is antimicrobial: it kills acne bacteria. Drying and peeling is an undesireable side effect, and dermatologists are working on all sorts of ways of combining BP with other treatments that reduce these undesireable side effects.