There are very few supplements that I would recommend to everyone who struggles with acne. I can think of only one supplement that most people with acne should at least try, zinc, and even that recommendation comes with a few qualifiers.
I’ll give you the essentials here, but you can find a more detailed discussion about zinc in the supplements section.
To date, 14 studies have looked into the effectiveness of zinc on acne. The best study comes from 2001 and compared zinc to minocycline (an oral antibiotic). This graph shows the number of inflammatory pimples over time in both groups.
Source: Dreno, B. et al. Multicenter randomized comparative double-blind controlled clinical trial of the safety and efficacy of zinc gluconate versus minocycline hydrochloride in the treatment of inflammatory acne vulgaris. Dermatology (Basel) 203, 135–40 (2001). https://www.ncbi.nlm.nih.gov/pubmed/11586012
The short story is that zinc seems to work well for inflammatory pimples but not so well on non-inflammatory (blackheads and whiteheads without inflammation) ones.
And that’s my recommendation. Anyone with inflammatory acne should try zinc. People who predominantly have non-inflammatory acne can also try, but I don’t expect it to work that well.
Effective dose seems to be 30mg/day or something in that ballpark. The tolerable upper limit, the dose that shouldn’t cause any side effects, is 40mg/day, and I wouldn’t supplement with anything above that.
Please be aware that about 30% of people taking zinc will get some gastrointestinal side effects, like abdominal pain or nausea. Taking zinc with food is supposed to reduce those.
There’s some discussion that zinc picolinate and zinc methionine have better bioavailability, and could be more effective than other zinc salts, but this is not proven, and the above study showed zinc gluconate definitely works.
Please don’t ask me what’s the best zinc supplement to buy. I have no way to answer that. But here are a few options that seem to be good value for money and use highly bioavailable forms of zinc: