Ingredient Beauty BenefitsOther · Zinc Sulfate
Oral zinc: both randomised trials for acne are from 1977
This is swallowed. The randomised trials we found are two, and both are from 1977. In the placebo-controlled one, the placebo group also improved significantly and there was no significant difference between the groups. In the other, it tied with tetracycline — but there was no placebo arm, so whether both worked or neither did is something that design cannot separate.
Last checked Sep 29, 2026
Start here
- What it is
Supplementing the essential trace element zinc by mouth, usually as a salt such as zinc sulphate.
- What it is used for
Long sold as a supplement for acne.
- How it is said to work
It is said to act on inflammation, on sebum and on bacteria.
There are no numbers and no citations in this box. What has been established, and how far, is below.
At a glance
- In pregnancy
- Not established
- Irritation
- Minimal
- Daytime use
- ✓ Fine
- How well established
- Not established
- Concentration studied
- Not disclosed
- Length of the studies
- 12 weeks
Not a measurement — reported irritation grouped into five steps. It varies between people.
“Concentration studied” and “Length of the studies” are taken straight from the research on this page. They are not a recommended dose, and the figure for each finding is written out in the text.
This is not how large the effect is but how well confirmed it is. It shows the highest grade among the findings on this page.
Oral zinc is supplementation with the essential trace element zinc. It has long been sold as a supplement for acne.
The point of this page is not an effect size but a date.
The randomised controlled trials we found are two, and both are from 1977. We have not found a trial of that design since. That is nearly fifty years.
The two trials looked at different things, and both ended in 'no difference found'.
- compared against placebo — both groups improved significantly, and there was no significant difference between them
- compared against tetracycline — no difference. But there is no placebo arm. At 12 weeks the acne score had fallen by about 70% in both groups
There is a temptation to read 'no difference from an antibiotic' as 'works as well as an antibiotic'. Without a placebo arm, that sentence cannot be written. This site drew the same distinction the same way on the vitamin K page.
And this page contains an example of the attitude this site wants to learn from. The authors of the 1977 placebo-controlled trial wrote down four limits of their own negative result. We carry them below.
Where this site does attach thick evidence on acne is elsewhere — azelaic acid, adapalene, benzoyl peroxide and salicylic acid. The acne page gathers those places together.
Contents
What is established
The same ingredient at a different strength, in a different formula, is a different product. These are the conditions the studies used.
No significant difference from placebo — and the authors listed four limits themselves
A double-blind controlled clinical trial in Acta Derm Venereol, 1977.
It gave 0.6 g of zinc sulphate daily. Twenty patients received zinc sulphate tablets and 19 were given placebo tablets. Thirteen of the zinc group and 12 of the placebo group took their medication throughout the 12-week period, while the rest were treated for 4 or 8 weeks. The trial ran from March through May 1975.
The results.
- in all patients the numbers of papular and pustular acne lesions on the face and the back were significantly reduced
- larger infiltrates remained practically unaltered during the trial
- no statistically significant difference in the improvement of the groups was demonstrable
- pretreatment serum zinc was normal in all patients and rose significantly in the zinc group as well as in the control group. The rise in the zinc group was significantly higher.
And now the real content of this entry — the authors wrote down the limits of their own negative result. Four of them.
One, the number of patients may have been too limited. It is 39 people, and 25 went the full 12 weeks.
Two, it may be related to the zinc dosage.
Three, the results may have been influenced by the unexplained rise in serum zinc values in the control group. The paper cannot explain why the blood zinc of people taking placebo went up. If the placebo group's zinc rose, the gap between the groups narrows.
Four, a possible weak beneficial effect of zinc might have been camouflaged by the seasonal variation in the severity of acne noted in this study. The trial ran March to May. If acne varies with the season, that variation improves both arms and covers the difference.
These four sentences are the attitude this site wants to learn from. Authors with a negative result did not stop at 'it does not work' but wrote four reasons their trial might have missed one. This site does not delete sentences like that.
So it sits at 'not established'. But here that badge means not 'it does not work' but 'this trial could not separate the two'. And in the fifty years since, we have not found a trial that would.
- Randomised controlled trial in people · 39 participants · 12 weeks · Compared with vehicle (same formula minus the active) · Funding not declared · Endpoint clinical events (cancers, lesion counts) PMID 70931
It tied with tetracycline — but there is no placebo arm
A double-blind trial in Br J Dermatol, 1977. The same year as the one above.
In 37 patients with moderate and severe acne, the effects of oral zinc and tetracyclines were compared with a double-blind technique.
The results.
- no difference in effect between the treatments was seen
- no side effects were noted in any group
- after 12 weeks of treatment, the average decrease in the acne score was about 70% in both groups
Now how to read it. This is the place on the page to be most careful.
First, there is no placebo arm. Both groups received something. So whether that '70%' is the effect of treatment, or the sum of time and season and expectation, is not something this trial separates.
Remember the 1977 placebo-controlled trial just above. There, the placebo group also improved significantly. Set the two side by side and it becomes hard to credit the 70% to zinc.
Second, therefore 'works as well as an antibiotic' cannot be written. The sentence that can be written is 'in this trial the score changes in the two groups were similar'. This site writes those as two different sentences.
Third, the abstract is short. Which tetracycline and how much, how much zinc, and who scored are not in it. We do not invent them.
Fourth, it is 1977. And antibiotic use for acne has changed a great deal since — because of resistance. This site does not guide antibiotic regimens. This entry records what zinc was compared against.
Fifth, the report of no side effects is from 37 people over 12 weeks. Oral zinc does have known problems. See cautions below.
So this entry also sits at 'not established'.
One last note to close the page. That both trials are from 1977 says more than anything else here. For nearly fifty years we have not opened a trial that asked this question again at that standard of design. Selling did not stop; the trials did.
- Randomised controlled trial in people · 37 participants · 12 weeks · Compared with another active ingredient · Funding not declared · Endpoint clinical events (cancers, lesion counts) PMID 145237
How to use it
- The dose in the trial was 0.6 g of zinc sulphate daily (1977). This site does not estimate other doses. Remember too that the amount of elemental zinc and the amount of the salt are different numbers.
- Taken on an empty stomach it often causes nausea. The abstracts do not state how it was taken, so this site does not specify a time.
- Oral zinc and topical zinc are different subjects. This page is the oral side.
- If you are looking at acne, start where the evidence is thick. Azelaic acid, adapalene, benzoyl peroxide and salicylic acid come first here.
- If acne is deep and leaving scars, seek care first. That is not a problem to handle with a supplement.
Cautions
- It interferes with copper absorption. Taking zinc in quantity over a long period can cause copper deficiency, which can show as anaemia and neurological symptoms. If you plan to take it long-term, check in a clinic.
- Nausea is possible. It is the commonest complaint with oral zinc.
- It and some antibiotics interfere with each other's absorption. Tetracyclines and quinolones do. If the doses coincide, both may be absorbed less. Check in a clinic if you take other medicines.
- It also interferes with iron supplements.
- There is an upper intake level. Taking several supplements can stack zinc without your noticing. Multivitamins often contain it.
- The trials above reported no side effects, but that is 37 and 39 people over 12 weeks.
- Check use in pregnancy or breastfeeding in a clinic.
- Zinc products put into the nose are unrelated to this page, and loss of smell has been reported with them. Do not run the two together.
With a new ingredient, apply a small amount somewhere inconspicuous, such as the inner arm, for two days first. Stop if it reddens or stings.
Related skin concerns
What this article relies on
- PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16