Now, I'm going to preface this by saying that I have dabbled in progesterone myself (not for acne specifically, but for other health issues), and some of the literature out there for "low progesterone / estrogen dominance" makes sense to me, even though estrogen dominance is not recognized by mainstream medicine.
HOWEVER, there is very little scientific evidence out there showing that low progesterone = acne or that high estrogen = acne. Yes, some books and a lot of naturopaths say that it does. Yes, some people have anecdotally experienced clearance of acne from estrogen dominance protocols (and I applaud their success).
I've been bamboozled by it all a little myself, until you realize that most of these naturopaths basically claim that progesterone fixes every possible symptom of any health problem you could have.
So I'm writing this post to explore what literature is (or isn't) out there that actually supports "low progesterone / estrogen dominance = acne."
Basically...what is progesterone?
Progesterone is a precursor in the steroid hormone cascade. It can be converted to testosterone and estrogen as needed, among other things.
So, as progesterone is also a precursor to testosterone/estrogen, if your progesterone is too high, progesterone itself can potentially cause testosterone/estrogen hormonal imbalances down the steroid hormone path.
Similarly, though, if progesterone is too low, it can cause a number of deficiency problems because progesterone is needed to complete various pathways. Could possibly a deficiency of progesterone lead to a hormonal imbalance that causes acne? Yes, I suppose it could. However I couldn't find any studies showing that particular outcome.
What does progesterone do for the skin?
Let's first go through what all the hormones do for the skin.
- Thins sebum secretions
- Reduces size and activity of sebaceous glands
- Increases activity of hyaluronidase (related to hyaluronic acid, related to skin moisture content)
As far as acne production goes, thinning sebum and reducing sebaceous activity is a HUGE positive.
- Increase sizes and activity of sebaceous glands
- Increases rate of cell turnover in the basal layer which thickens the skin around the sebaceous duct
Increasing sebum production is bad when it comes to acne, and so is thickening the skin around the sebaceous duct because it makes a sebum plug -> acne more likely. If you've forgotten how that links together, see this image:
Okay, but what does progesterone do? The short answer is that the direct relationship between progesterone and the skin has not been studied much. The skin has progesterone receptors. Their action is mostly unknown.
It does seem to have some anti-inflammatory effects on the skin. Not necessarily directly related to acne, but conceivably could have an effect since acne involves inflammation:
Again, is that directly related to the sebum plug -> acne chain in the picture? No, but some anti-inflammatory action on the skin could still help.
There is evidence that anti-androgens may help in the treatment of acne vulgaris. We therefore performed a double-blind trial to assess the effect of topically applied progesterone on sebum excretion rate. Thirty-eight patients took part in the trial which was for 3 months. The preparation had no etfect in males. However, a signiticant reduction in sebum excretion rate was found in females, the etfect being maximal at the end of the second month. There was a significant loss of effect at the end of the third month and this was not related to deterioration of the progesterone preparation.
I got bad side effects on anti-androgens like spironolactone or saw palmetto. Does progesterone have anti-androgenic effects?
Natural progesterone (and SOME types of synthetic progestins) has a high affinity for 5 alpha reductase, which means that it competes for 5 alpha reductase with testosterone. Why is this a good thing? Because testosterone uses 5 alpha reductase to convert to dihydrotestosterone (DHT) which has been implicated as a potent factor in acne.
I really want to stress this point, because some who use progesterone claim that "reducing androgenic activity doesn't help my acne." BY USING PROGESTERONE you are exerting an anti-androgenic influence on your body!
Perhaps progesterone's particular mechanism worked well for you and spironolactone's didn't. But please realize that we are still attacking the same thing here, which is an ANDROGENIC problem -> acne.
Can HIGH progesterone cause acne?
We are talking about natural progesterone here. (Many synthetic progestins, have been shown over and over again to have androgenic activity.)
- Progesterone can increase sebaceous hyperplasia (at least in rats -- see Haskin's study)
- Progesterone as effective as testosterone in stimulating sebaceous glands (at least in the elderly -- see Smith's study)
However, these studies have been countered by other studies (Strauss and Kligman) that say that natural progesterone is largely "sebaceous gland neutral." So the jury is still out on this one.
How does progesterone reduce estrogen?
PROGESTERONE has long been considered an antagonist of oestrogen action1. The delicate balance and interactions between these ovarian hormones are essential for many reproductive functions. Early studies in chick oviducts and uteri of rats and mice have shown that the simultaneous administration of progesterone and oestrogen resulted in inhibition or modification of oestrogen-induced growth of these target organs2–5. One possible mechanism by which progesterone could be antagonistic to oestrogen is by suppressing the quantity of cytoplasmic oestrogen receptor. It is generally held that the mechanism by which oestrogen, O, stimulates uterine growth depends on the binding of O to cytoplasmic receptors, Rc, to form RCO complexes6. These RCO complexes are translocated to nuclear sites where they probably stimulate nuclear events that cause the uterus to grow7. Translocation and nuclear accumulation of receptor–oestrogen complexes, RnO, are accompanied by a concomitant decrease in the quantity of Rc (ref. 8). During the period when Rc is reduced, the uterus is insensitive to additional exogenous oestrogen9. Gradually Rc is replenished by processes which may involve reutilisation and/or resynthesis8. Work from our laboratory indicates that the mechanism of action of non-steroidal oestrogen antagonists resides in their inability to stimulate the replenishment of the cytoplasmic oestrogen receptor, Rc, thereby rendering oestrogen responsive tissues less sensitive to oestrogen10,11. The possibility that progesterone might also act as an oestrogen antagonist by reducing the amount of oestrogen Rc has been suggested12,13. In this report, we demonstrate that progesterone does decrease the quantity of oestrogen receptors by interfering with the replenishment of Rc and that this decrease results in a reduced sensitivity of uterine tissue to oestrogen.
Does high estrogen cause acne?
I could not find any studies linking high estrogen levels to acne. If anything, most research indicates that while excessively high estrogen has other side effects (such as weight gain), estrogen overall is extremely beneficial for acne.
Does lowering androgenic activity or raising estrogenic activity change the menstrual cycle, via spironolactone?
The reason spironolactone is indicated for messing with the menstrual cycle is, as far as research has shown, because of its PROGESTOGENIC effect. Not to get huffy on this, but people keep stating that "lowering androgenic activity" or "raising estrogen" changes the menstrual cycle, and then point to spironolactone as proof. It is the progestogenic activity that is most likely to blame (citation). Also think: you can have a progestin-only birth control pill. Why? Because progesterone is ultimately what controls the cycle.
Another point here, is that Finasteride, which has been often compared to spiro, is very powerful anti-androgen but does not have progestogenic effects. As such, Finasteride does not interfere with the menstrual cycle (citation). So again, it is not the testosterone or the estrogen that really messes with your periods, it is progesterone. This is also why some doctors recommend cycling spironolactone for patients who are very sensitive to the weak progestogenic effect.
So from my (admittedly limited) study...
High estrogen does not cause acne.
Low progesterone does not cause acne (at least not directly).
High progesterone can potentially cause acne.
Progestogenic effects are responsible for major menstrual cycle changes.
Androgens can cause acne.
Progesterone's anti-acne mechanism is primarily its anti-androgenic action.
If one is progesterone deficient, progesterone may potentially solve health problems (possibly including acne) via its general ability to create and regulate other hormones.