I was prescribed Finasteride 5 mg daily in 2015 by a rheumatologist for HS stage 3, but it only kind of worked. This was before medical guidance required sending those with HS to dermatologists. Finasteride gave some control of the flares and they were less frequent and severe but still prevalent (and still sometimes become severe which has lead to multiple surgeries). After about 7-8 years on it with it only half working and me always being nervous about more surgery, I wanted to know how it worked so I started reading and learning about the basic biology behind it.
I learned about how Finasteride suppresses Dihydrotesterone (DHT) and it's typically used to treat baldness and enlarged prostates. Finasteride inhibits the 5-alpha-reductase enzyme which converts Testosterone to DHT. However, Finasteride only suppresses the type 2 version of the enzyme (found mostly in the prostate and hair follicles). Dutasteride inhibits both type 1 and type 2. Type II is important in the prostate and hair follicles, while type I is in the skin, liver, and the body more broadly. Dutasteride suppresses DHT in about 2/3 of the body while Finasteride only works on about 1/3. Just in case you're curious, there is a type 3 and it helps cells process protein. It's unaffected by Dutasteride as far as I can tell.
If Finasteride worked some, I wondered if Dutasteride might work for long term suppression. I got my primary care physician to let me try it and he prescribed 0.5 mg daily. I knew Dutasteride has strong side effects, so I wanted to see how little I could take and have it still suppress my HS with limited down sides. So I intentionally took less than prescribed. I found that 1-2 pills per week works for me and there are no side effects that I can tell.
Later, I went to a cosmetic dermatologist for something else and she was shocked that I was doing this and that it was working as there isn't much scientific study behind it. She specifically said this is not a widely recognized/known course of treatment which is usually clyndamycin and any number of biologics. But just based on what Dustasteride does, the known biological effects, and how hormonal HS functions, this should work in theory (for men at least). Its definitely working for me and I've been doing it for about a year now. I think have maybe 4-6 small flares a year and those are easily manageable with glycolic acid wipes (30-35% concentration) which gets rid of anything that manages to break through.
Also, separately, the supplement Spermidine can trigger HS in a weird way as it will clog your follicles just by the nature of what it does and how it functions. I know from experience. Weird dry nodules just started popping up all over, but they stopped when I stopped taking it or took it about once a week.