Zinc: Does It Actually Work?
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What Is Zinc?
Zinc is an essential mineral your body needs for over 300 enzyme reactions. It plays a big role in immune function, wound healing, and cell division. Your body doesn’t store it, so you need a steady supply from food or supplements.
You’ll see zinc marketed for everything from fighting colds to boosting testosterone to clearing acne. Some of these claims have solid research behind them. Others don’t.
We analyzed 3 meta-analyses and systematic reviews covering 67 individual studies. Here’s what the data actually shows.
The Evidence, Claim by Claim
The sections below break down each claim with real numbers from published meta-analyses. Every effect size, confidence interval, and study count comes from peer-reviewed research.
Immune Function and Colds: It Works
This is zinc’s strongest claim. A 2024 Cochrane review looked at 34 randomized controlled trials with over 8,500 participants. Zinc treatment shortened cold duration by about 2.4 days. That’s a meaningful difference when you’re stuck in bed with a stuffy nose.
Zinc lozenges are the key here. A 2017 re-analysis focusing only on adult lozenge studies found colds were 33% shorter across 7 trials with 575 people. The lozenges deliver zinc right where the cold virus lives, in your throat.
Zinc also helps your immune system in measurable ways. A 2022 meta-analysis of 35 trials found it lowers CRP (an inflammation marker) by 32.4 mg/L and boosts CD4 immune cells. Both results were statistically significant.
One catch: for prevention, the evidence isn’t as strong. The Cochrane review found zinc reduced the risk of catching a cold, but the result just missed statistical significance (RR 0.93, CI 0.85-1.01). It’s better for treatment than prevention.
Testosterone: Don’t Believe the Hype
A 2023 systematic review looked at 8 clinical studies and 30 animal studies. But here’s the problem. Nobody pooled these into an actual meta-analysis. There’s no combined effect size.
The studies that showed testosterone increases were all done in men who were zinc-deficient. That’s an important detail. If you’re eating a normal diet in a developed country, you’re probably not zinc-deficient. And if your zinc levels are already normal, supplementing more won’t raise your testosterone.
This is a classic case of supplement marketing stretching the data. “Zinc supports testosterone” is technically true, but only if you’re deficient. For healthy guys with normal zinc, it doesn’t do anything.
Acne: Worth a Shot, Especially Topical
A 2020 meta-analysis of 25 studies (12 RCTs) with 2,445 participants found zinc reduces acne papule count with a moderate effect size (SMD 0.730). People with acne also tend to have lower serum zinc levels, about 12.3 ug/dL lower than people without acne.
The interesting finding: topical zinc worked better than oral zinc. If acne is your goal, a zinc-containing face product might help more than swallowing pills.
Oral zinc isn’t useless for acne. It just probably won’t clear things up on its own. Think of it as one tool in your toolbox, not a magic fix.
How to Take Zinc
For colds: Start zinc acetate or zinc gluconate lozenges within 24 hours of your first symptoms. Take one every 2-3 hours while awake. This is the protocol that works best in the research.
For daily immune support: Take 15-30mg of zinc picolinate with food. Zinc picolinate absorbs well and is gentle on the stomach.
For acne: Talk to a dermatologist about topical zinc products. If you want to try oral zinc, 30mg daily is a reasonable dose.
Don’t take zinc on an empty stomach. It’ll make you nauseous. Always take it with food.
Who Should NOT Take Zinc
Don’t take high-dose zinc (40mg+) long-term without medical supervision. It depletes copper, which can cause anemia and neurological problems. If you take more than 30mg daily, consider adding a small copper supplement (1-2mg).
Be careful if you take antibiotics, especially tetracyclines or fluoroquinolones. Zinc binds to these drugs and blocks their absorption. Take zinc at least 2 hours apart from antibiotics.
Avoid zinc supplements if you have kidney disease, since your body can’t excrete excess zinc properly.
If you take thiazide diuretics, know that they increase zinc loss through urine by up to 60%. You might actually need more zinc, not less. Talk to your doctor.
The Bottom Line
Zinc is one of the better-supported supplement claims out there, at least for immune function. The Cochrane review data is strong. Zinc lozenges genuinely shorten colds.
But the testosterone marketing is overblown. Unless you’re actually deficient, zinc won’t move the needle on your T levels. And for acne, topical zinc is more promising than popping pills.
Stick to 15-30mg daily for general health. Keep zinc lozenges on hand for when you feel a cold coming on. That’s the evidence-based approach.
The Evidence, Claim by Claim
Boosts immune function and shortens colds ✓ Works
A Cochrane review of 34 trials with over 8,500 people found zinc shortens colds by about 2.4 days on average. A separate re-analysis of lozenge-only studies found colds were 33% shorter. Zinc also lowers CRP (an inflammation marker) and boosts CD4 immune cells.
Very high heterogeneity (I2 = 97%) means the size of the benefit varies a lot between studies. Different zinc forms, doses, and timing explain much of this variation. The direction is clear though. Zinc helps with colds.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed in Cochrane review |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Zinc acetate lozenges | 7 | -1.8 |
| Zinc gluconate lozenges | 10 | -2.1 |
| Oral supplements | 17 | -2.9 |
Increases testosterone ✗ No Evidence
A systematic review found 8 clinical and 30 animal studies. But nobody has pooled these into a proper meta-analysis. The studies showing testosterone increases were done in zinc-deficient men. Healthy men with normal zinc levels don't see a benefit.
No pooled effect size exists. This is a systematic review only, not a meta-analysis. The testosterone effect appears real only when you're actually deficient in zinc. Most men in developed countries aren't.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | no pooled analysis exists to assess |
|---|
Treats acne ? Maybe
25 studies with about 2,400 people found zinc reduces papule count with a moderate effect size. People with acne tend to have lower serum zinc levels. Topical zinc worked better than oral zinc in head-to-head comparisons.
The effect is real but moderate. Topical zinc is more promising than swallowing zinc pills for skin. Oral zinc alone probably won't clear severe acne, but it may help as part of a broader treatment plan.
View full statistical analysis
Publication Bias Assessment
| Egger's Test | z = —, p = — | not formally assessed |
|---|
Subgroup Analysis
| Subgroup | Studies (k) | Effect (g) |
|---|---|---|
| Topical zinc | ||
| Oral zinc |
Dosage Guide
| Effective Range | 15-40mg |
|---|---|
| Optimal Dose | 30mg |
| Best Form | Zinc picolinate, zinc gluconate, or zinc acetate lozenges for colds |
| Timing | With food to avoid nausea. Lozenges every 2-3 hours at cold onset. |
| Time to Effect | Lozenges work within first 24 hours of cold symptoms. General immune benefits take 2-4 weeks. |
| Cycling | No cycling needed at standard doses (15-30mg). Take breaks from high doses (40mg+). |
| Notes | For colds, zinc acetate or gluconate lozenges are best. For daily supplementation, zinc picolinate absorbs well. Don't exceed 40mg/day long-term without medical supervision. |
Don't Take If
- Copper deficiency (zinc competes with copper absorption)
- Kidney disease (impaired zinc excretion)
- HIV/AIDS medications (zinc may interfere with certain antiretrovirals)
Drug Interactions
| Medication | Risk | Why |
|---|---|---|
| Antibiotics (tetracyclines, quinolones) | high | Zinc binds to these drugs and reduces their absorption. Take 2 hours apart. |
| Penicillamine | high | Zinc reduces absorption of penicillamine. Take 2 hours apart. |
| Diuretics (thiazides) | moderate | Thiazide diuretics increase zinc excretion in urine by up to 60%. |
| Copper supplements | moderate | Zinc and copper compete for absorption. High zinc depletes copper over time. |
Possible Side Effects
- Nausea when taken on an empty stomach
- Metallic taste from lozenges
- Copper depletion at doses above 40mg/day for extended periods
- GI distress at high doses
What to Buy
Disclosure: Links below are affiliate links. We earn a commission if you buy. We never recommend products that fail our evidence checks.
Thorne Zinc Picolinate 30mg
NSF Certified for Sport, well-absorbed picolinate form, correct 30mg dose
What to Avoid
Frequently Asked Questions
Does zinc actually shorten colds?
Yes. A Cochrane review of 34 trials with over 8,500 people found zinc shortens colds by about 2.4 days. Zinc lozenges work best when you start them within 24 hours of your first symptoms. A separate analysis of lozenge-only studies found colds were 33% shorter.
What's the best form of zinc for colds?
Zinc acetate or zinc gluconate lozenges. They deliver zinc directly to your throat where the cold virus replicates. Swallowing a zinc pill doesn't work as well for colds specifically. For daily immune support, zinc picolinate capsules absorb well.
Does zinc boost testosterone?
Only if you're deficient. A systematic review of 8 clinical studies found no pooled evidence for testosterone increases. The positive studies were all done in zinc-deficient men. If your zinc levels are already normal, don't expect any testosterone changes.
Can zinc help with acne?
Maybe. A meta-analysis of 25 studies found zinc reduces papule count with a moderate effect size. Topical zinc works better than oral zinc. People with acne tend to have lower serum zinc levels. It's worth trying as part of a broader acne treatment plan, but it probably won't clear severe acne on its own.
How much zinc is too much?
Don't take more than 40mg per day long-term unless a doctor tells you to. High-dose zinc (50mg+) depletes copper over time, which can cause anemia and neurological problems. For colds, short bursts of higher-dose lozenges are fine. For daily use, stick to 15-30mg.