Printed from https://bottledhope.co/supplements/zinc/. Last reviewed 2026-09-24. Check the site for the latest version.
Zinc
An essential mineral in meat, seafood and fortified cereals. It is sold in cold remedies and in eye supplements marketed for macular degeneration.
Explained simply · Last reviewed
What it is
Zinc is an essential mineral found in food and sold as a dietary supplement. The NIH Office of Dietary Supplements (ODS) says the body needs it for the work of hundreds of enzymes. It says zinc plays a part in immune function, making protein and DNA, wound healing, and cell signaling and division. It adds that zinc is found in some cold lozenges, over-the-counter cold remedies and denture creams.
More about Zinc
The NIH Office of Dietary Supplements (ODS) says the body needs it for the work of hundreds of enzymes. It says zinc plays a part in immune function, making protein and DNA, wound healing, and cell signaling and division. It adds that zinc is found in some cold lozenges, over-the-counter cold remedies and denture creams.
According to the same fact sheet, zinc is also involved in the sense of taste, and in healthy growth during pregnancy, childhood and adolescence. Most of the zinc in the body is stored in muscle and bone.
ODS says meat, fish and other seafood are the richest food sources, and oysters contain more per serving than any other food. Eggs and dairy products contain some, and many breakfast cereals are fortified with it. Beans, nuts and whole grains contain zinc too, but the body absorbs less of it from them, because they also contain phytates, which bind zinc in the gut.
ODS says zinc is sold on its own, combined with other ingredients, and in many multivitamin and mineral products. It says some nasal sprays and homeopathic products that contain zinc are often sold over the counter for cold and flu symptoms and for immune support. It also describes supplements that contain zinc, copper and certain antioxidants, known as AREDS formulations after the studies that tested them. A 2023 Cochrane review of eye supplements notes that antioxidant vitamin and mineral supplements are increasingly marketed for age-related eye diseases, including age-related macular degeneration.
Also known as: zinc gluconate, zinc acetate, zinc sulfate, zinc citrate, zinc oxide, zinc picolinate
At a glance
Safety: known risks, 7 groups who should avoid it or take extra care and 5 documented interactions. See Safety ↓Claims made about Zinc, and how strong the evidence is for each:
- Taking zinc by mouth prevents coldsEvidence rating: Evidence against
- Shortens coldsEvidence rating: Limited
- Slows progression to late age-related macular degeneration in people who already have itEvidence rating: Moderate
- Helps chronic leg ulcers healEvidence rating: Limited
- Improves blood sugar control in type 2 diabetes and prediabetesEvidence rating: Limited
- Improves acne when taken by mouthEvidence rating: Limited
Each rating follows our published rules and the sources cited for it. We don’t add our own medical judgment. How we rate
Safety
Read this before the ratings below.
Risks
- The cited health authority reports that high zinc intakes can cause nausea, dizziness, headaches, stomach upset, vomiting and loss of appetite.
- The authority states that, if used for weeks, doses of 50 mg zinc or more, typically from supplements or from overusing zinc-containing denture creams, can interfere with copper absorption and cause low copper status, reduce immune function, and lower HDL cholesterol. It notes that food alone rarely provides that much zinc.
- Chronic, excessive use of denture adhesive creams that contain zinc can lead to zinc toxicity, which the authority says can cause copper deficiency and neurological disease, including sensory ataxia and myelopathy, as well as anemia. It notes that zinc-free denture creams are available.
- Loss of the sense of smell with nasal zinc. In a 2022 guidance document, the FDA states that by 2009 it had received more than 130 reports of anosmia (loss of the sense of smell) associated with Zicam homeopathic intranasal zinc products, and that using them as labeled would give a significant daily exposure to intranasal zinc, raising a serious safety concern. A 2021 review notes post-marketing reports of long-lasting anosmia with a zinc gluconate nasal gel. The 2024 Cochrane review found no cases reported in the nasal-zinc trials it included, and says information about specific side effects is uncertain.
- Taking zinc to treat a cold probably increases non-serious side effects, according to the 2024 Cochrane review (moderate certainty). The most common were altered taste, stomach and bowel discomfort, dryness of the mouth, throat or nose, pain or irritation of the mouth or nose, and headache. A 2021 review found the same increase, naming nausea and mouth or nasal irritation, and says these may limit tolerability for some people. In a 2024 opinion article, Hemilä and Chalker dispute the Cochrane side-effect analysis, arguing that it did not take account of differences in lozenge composition and that a risk ratio is misleading for mild side effects.
- In the macular degeneration trials, stomach and bowel symptoms were the main reported side effect, and some people stopped taking zinc because of them. In the largest trial, people taking zinc reported anemia more often, although their hematocrit was the same, and men had a higher risk of genitourinary problems; a later trial saw no difference in these problems between higher and lower zinc amounts. In the smaller zinc sulfate trials, no one developed copper-deficiency anemia. The Cochrane reviewers rate this harms evidence very low certainty and say most trials were too small to detect rare harms.
- In the acne trials, zinc had the highest rate of reported side effects of the oral supplements a 2023 review assessed, mostly nausea, vomiting, abdominal pain and indigestion. The reviewers note zinc was often given at many times the recommended daily allowance.
- A 2022 review of zinc taken to prevent infections reports mild stomach discomfort and bad taste. In the leg-ulcer trials, side effects did not appear to be a major problem; a few people taking zinc stopped because of nausea, dizziness or itching, and two taking placebo stopped because of dizziness or a skin rash.
Who should avoid it or take extra care
- Children and teenagers: their tolerable upper intake levels are lower than for adults (see the reference intakes below).
- People who use zinc-containing denture creams heavily or for years.
- Anyone considering zinc nasal sprays or gels: see the loss-of-smell risk above.
- People who have or are developing age-related macular degeneration: the cited authority advises talking to a health care provider about zinc intake and the formulations used in the AREDS studies.
- Current or former smokers, and people exposed to asbestos, considering an eye supplement based on the original AREDS formula: the 2023 Cochrane review notes that beta-carotene, one of its ingredients, is associated with an increased risk of lung cancer in people who have smoked or been exposed to asbestos.
- People given zinc as a medical treatment: the authority says the upper limits do not apply to them and that they should be under the care of a physician.
- Anyone taking the medications listed below on a regular basis: the authority advises discussing zinc status with a health care provider.
Documented interactions
- Quinolone and tetracycline antibiotics (for example ciprofloxacin/Cipro): Zinc and these antibiotics can interact in the gut and stop both being absorbed if taken at the same time. Taking the antibiotic at least 2 hours before or 4 to 6 hours after the zinc supplement minimizes this. Source [1]
- Penicillamine (used for rheumatoid arthritis and Wilson disease): Zinc can reduce the absorption and action of penicillamine. Taking them at least 1 hour apart minimizes this. Source [1]
- Thiazide diuretics (for example chlorthalidone, hydrochlorothiazide): These increase the zinc lost in urine, which lowers blood zinc levels. Source [1]
- Iron supplements: Supplements containing 25 mg elemental iron or more, taken at the same time as zinc, can reduce zinc absorption and blood zinc levels. Source [1]
- Magnesium: Very high doses of zinc from supplements might interfere with magnesium absorption and disrupt magnesium balance. Source [1]
Safety sources: Source [1]Source [2]Source [3]Source [4]Source [5]Source [6]Source [7]Source [8]Source [9]
What the evidence says
Each claim is rated on its own evidence. Ratings follow the scale on our methodology page.
Taking zinc by mouth prevents colds Evidence rating: Evidence against
People take zinc by mouth hoping it will stop them catching colds.
A 2024 Cochrane review found zinc may make little or no difference to the chance of catching a cold or the number of colds, and rated both findings low certainty.
A 2024 Cochrane review pooled nine prevention trials in 1,449 children and adults. Eight gave zinc by mouth, as lozenges, syrups, tablets or capsules, and one gave it as a nasal gel. Four of the nine deliberately infected volunteers with a cold virus. Most of the people in those trials were children taking zinc syrup or tablets, in trials that counted colds caught naturally. The review found that zinc may make little or no difference to the chance of catching a cold, or to the number of colds over 5 to 18 months. It rated how sure it could be of both findings (certainty) as low.
In the same review, among people who did catch a cold, zinc probably made little or no difference to how long it lasted (moderate certainty). Whether it shortened individual symptoms such as cough was very uncertain (very low certainty). The reviewers had too few trials to compare ways of taking zinc. They note that, because certainty was low, further study may identify specific populations, interventions or outcomes where zinc has some preventive activity. The NIH Office of Dietary Supplements reports the Cochrane conclusion. It says other recent reviews also found that zinc does not reduce the risk of colds.
A 2021 review in adults reported fewer community-acquired respiratory infections with zinc (moderate certainty). It counted these as mild to moderate symptoms such as a cold. About 95% of the weight in that result came from two trials of a zinc nasal spray. The two trials of zinc capsules taken by mouth carried under 5% between them, and the review gave no combined estimate for them. One found fewer infections in older adults, the other no difference in young adults. The same review found that zinc lozenges or a nasal gel did not prevent colds in people deliberately infected with a cold virus (moderate certainty).
The Cochrane authors give the two nasal-spray trials as one possible reason the reviews disagree. They say those trials are available only in Chinese and were not found in their searches. Nasal zinc also carries a reported risk of loss of smell (see the safety section). A 2022 review of zinc supplements taken by healthy people excluded lozenges and nasal sprays. It reported benefit in three of four trials in children living outside the US, and three of those four are also in the Cochrane review. Its authors say the studies lacked methodological rigour and were small, and that gaps in the evidence prevent firm statements.
Shortens colds Evidence rating: Limited
People take zinc when a cold starts, hoping to get over it sooner.
A 2024 Cochrane review found zinc taken once a cold starts may shorten it by about two days, rated low certainty, and called the evidence insufficient for firm conclusions.
The 2024 Cochrane review found that zinc taken once a cold has started may shorten it by about two days on average. That result came from eight trials in 972 people. It rated this low certainty because of risk of bias and large differences between trials. Whether fewer people were still ill at the end of the trials, and whether symptoms were less severe, was very uncertain (very low certainty). The Cochrane authors say the evidence is not strong enough for firm conclusions or to recommend zinc for colds.
A 2021 review in adults looked at zinc dissolved in the mouth or used in the nose. It found that symptoms resolved about two days earlier (very low certainty). It found that symptoms were less severe on the third day, but not on average across the illness (low certainty). The NIH Office of Dietary Supplements reports that zinc lozenges or syrup taken shortly after a cold starts appear to shorten it. It says they do not appear to make it less severe.
In a 2024 opinion article, Hemilä and Chalker dispute the Cochrane analysis. They argue that it should not have pooled lozenges with nasal products, or children with adults. They say it left out a lozenge trial without explanation, and that the effect should be measured as a proportion of how long a cold lasts. Re-analyzing the lozenge trials in adults that way, they report that colds were shortened by 37%.
Slows progression to late age-related macular degeneration in people who already have it Evidence rating: Moderate
People with age-related macular degeneration take eye supplements containing zinc, hoping to slow it down.
A 2023 Cochrane review found people taking zinc were less likely to progress to late age-related macular degeneration, at moderate certainty, with most evidence from one large US trial.
A 2023 Cochrane review of supplements for people who already have age-related macular degeneration (AMD) found five trials comparing zinc with placebo. Most of the evidence came from one large US trial (AREDS). It gave zinc as zinc oxide together with copper, and followed people for an average of six years. The reviewers found that people taking zinc were less likely to progress to late AMD and to neovascular AMD (moderate certainty). For geographic atrophy and for losing three or more lines of vision, the estimates also favored zinc. But the review's results for both were consistent with no effect (moderate certainty).
The review also found that the AREDS formula of vitamins C and E, beta-carotene and zinc probably slows progression to late AMD (moderate certainty). The reviewers say people with intermediate AMD have a higher chance of benefiting than people with early AMD, because their risk of progression is higher.
The reviewers note that the finding was drawn from one large study in a "relatively well-nourished American population". Until it is replicated, they say, it is not known whether it applies more generally. The review looked only at people who already have AMD. The NIH Office of Dietary Supplements reports that AREDS formulations slow progression in people at high risk of the advanced form. The original AREDS formula also contains beta-carotene: see the caution for smokers in the safety section.
Sources: Source [1]Source [2]
Helps chronic leg ulcers heal Evidence rating: Limited
People with slow-healing leg ulcers take zinc hoping the ulcers will close.
A 2014 Cochrane review found no statistically significant difference in healing; a 2025 review found more ulcers healed with zinc and rated that moderate certainty.
A 2014 Cochrane review found six small trials in 183 people with leg ulcers, all testing oral zinc sulfate. Pooling the four placebo-controlled trials in venous ulcers showed no statistically significant difference in healing. The reviewer concluded that oral zinc sulfate does not appear to aid healing, while noting that every trial was small and at unclear risk of bias. Its plain-language summary says of the trials that "all were too small to show a benefit, even if one exists".
A 2025 meta-analysis pooled five trials in 178 people with chronic ulcers. Four tested oral zinc sulfate and one zinc oxide applied to the skin. It found that more ulcers healed with zinc, and rated the evidence moderate certainty. Its authors describe the included studies as relatively old, small and of suboptimal quality. They say the findings "should be interpreted with caution".
The two reviews disagree, and this page takes the lower rating.
Sources: Source [1]Source [2]
Improves blood sugar control in type 2 diabetes and prediabetes Evidence rating: Limited
People with type 2 diabetes or prediabetes take zinc hoping it will bring their blood sugar down.
A 2019 review found lower fasting glucose and HbA1c with zinc, but the NIH Office of Dietary Supplements says the evidence is insufficient for any conclusions about zinc's effect on type 2 diabetes.
A 2019 meta-analysis pooled 32 placebo-controlled comparisons in 1,700 participants. They had type 2 diabetes, prediabetes, overweight or obesity (including children with obesity), or gestational diabetes. It found lower fasting glucose, HbA1c, fasting insulin and insulin resistance with zinc. Its authors concluded that zinc may have clinical potential as an add-on for preventing or managing diabetes.
The same authors report that results varied relatively widely between studies (heterogeneity), and that some trials were small. They note that most of the trials were in Asian countries. Their analysis also included some trials that combined zinc with other nutrients.
The NIH Office of Dietary Supplements describes this and other meta-analyses. It concludes that "the evidence to date is insufficient to support any conclusions" about the effect of zinc supplementation on the prevalence or severity of type 2 diabetes. It notes that a 2015 Cochrane review of zinc for preventing type 2 diabetes found only three trials, in 128 people, and concluded that evidence was lacking. The sources disagree, and this page takes the lower rating.
Sources: Source [1]Source [2]
Improves acne when taken by mouth Evidence rating: Limited
People with acne take zinc by mouth hoping it will clear their skin.
A 2023 review found mixed results across 15 zinc studies, with about half failing to show a benefit, and judged most of them poor quality.
A 2023 systematic review of oral supplements for acne found that zinc was the most studied, in 15 articles, with mixed results. Four of six fair-quality studies and four of nine poor-quality studies found zinc effective. Studies using higher amounts more often did. None of the zinc studies was rated good quality.
The reviewers describe most zinc studies as poor quality, with results that varied substantially between them. They suggest that small samples, short follow-up, and varying formulations and amounts may explain why about half failed to show an effect.
Sources: Source [1]
How and when to take it
What the cited sources say about taking it. Ask your doctor or pharmacist what applies to you.
Keep it apart from quinolone and tetracycline antibiotics
Zinc and these antibiotics can stop each other being absorbed when taken at the same time. The cited authority says taking the antibiotic at least 2 hours before or 4 to 6 hours after the zinc supplement minimizes this. Source [1]
Keep it apart from penicillamine
Zinc can reduce the absorption and action of penicillamine. The cited authority says to take the two at least 1 hour apart. Source [1]
An iron supplement taken at the same time can reduce how much zinc you absorb
The cited authority reports that supplements containing 25 mg elemental iron or more, taken at the same time as zinc, can reduce zinc absorption and blood zinc levels. The iron added to fortified foods does not significantly interfere. Source [1]
Check the label for elemental zinc
The cited authority notes that the Supplement Facts panel declares the amount of elemental zinc, not the weight of the whole zinc compound. Source [1]
Which form the evidence used
Supplements are sold in several forms. This is what the sources on this page say about them — which form the research used, and any comparison those sources themselves made. Where they made none, this page does not rank the forms.
Zinc gluconate or zinc acetate lozenges, What the sources supportDetails
Half of the trials in the cited 2024 Cochrane review (17 of 34) used lozenges, in acetate, gluconate or orotate form, and gluconate was the most common. The reviewers had too few studies to test formally whether the form made a difference to how long colds lasted. They observed that acetate and gluconate seemed to shorten colds by just over two days compared with placebo, while zinc sulfate showed no reduction beyond half a day. Side effects did not differ between acetate and gluconate. Source [1]
Zinc citrate or zinc gluconate (tablets and capsules), What the sources supportDetails
The cited authority reports that zinc is absorbed similarly from supplements containing zinc citrate or zinc gluconate, at approximately 61% in young adults, and that absorption from zinc oxide is 50%. This is about absorption, not about whether zinc helps any of the claims rated below. Source [1]
Zinc oxide, What the sources supportDetails
Most of the macular degeneration evidence the 2023 Cochrane review rates comes from one large trial (AREDS), which gave zinc as zinc oxide together with copper. The cited authority reports that zinc oxide is absorbed less completely than zinc citrate or zinc gluconate. Source [1]Source [2]
Zinc sulfate, What the sources supportDetails
Every trial in the 2014 Cochrane review of leg ulcers tested oral zinc sulfate, and most of the acne trials in the 2023 acne review used zinc sulfate. Neither review compared it with other forms. Source [1]Source [2]
Reference intake values
Quoted exactly as published by the cited authority. These are population reference values, not a recommendation for you. Ask your doctor or pharmacist what applies to your situation.
Men, 19+ years
- Recommended intake
- 11 mg
- Upper limit
- 40 mg
- Source
- Source [1]
Women, 19+ years
- Recommended intake
- 8 mg
- Upper limit
- 40 mg
- Source
- Source [1]
Pregnancy, 19+ years
- Recommended intake
- 11 mg
- Upper limit
- 40 mg
- Source
- Source [1]
Lactation, 19+ years
- Recommended intake
- 12 mg
- Upper limit
- 40 mg
- Source
- Source [1]
Males, 14–18 years
- Recommended intake
- 11 mg
- Upper limit
- 34 mg
- Source
- Source [1]
Females, 14–18 years
- Recommended intake
- 9 mg
- Upper limit
- 34 mg
- Source
- Source [1]
Children, 9–13 years
- Recommended intake
- 8 mg
- Upper limit
- 23 mg
- Source
- Source [1]
Children, 4–8 years
- Recommended intake
- 5 mg
- Upper limit
- 12 mg
- Source
- Source [1]
Children, 1–3 years
- Recommended intake
- 3 mg
- Upper limit
- 7 mg
- Source
- Source [1]
What the upper limits count: “The FNB has established ULs for zinc from food and supplements for healthy individuals based on the levels of zinc that have an adverse effect on copper status” Source [1]
Sources
- Zinc for prevention and treatment of the common coldCochrane Database of Systematic Reviews, 2024 · Systematic review · Primary source · Certainty: very low
- Zinc for the prevention or treatment of acute viral respiratory tract infections in adults: a rapid systematic review and meta-analysis of randomised controlled trialsBMJ Open, 2021 · Meta-analysis · Primary source · Certainty: very low
- Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systematic ReviewNutrients, 2022 · Systematic review · Primary source
- Zinc: Fact Sheet for Health ProfessionalsNIH Office of Dietary Supplements, 2026 · Health authority summary · Primary source
- Shortcomings in the Cochrane review on zinc for the common cold (2024)Frontiers in Medicine, 2024 · Published comment · Not counted toward ratings
- Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degenerationCochrane Database of Systematic Reviews, 2023 · Systematic review · Primary source · Certainty: very low
- Oral zinc for arterial and venous leg ulcersCochrane Database of Systematic Reviews, 2014 · Systematic review · Primary source
- Systematic review and meta-analysis of the effect of zinc on wound healingBMJ Nutrition, Prevention & Health, 2025 · Meta-analysis · Primary source · Certainty: moderate
- Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trialsThe American Journal of Clinical Nutrition, 2019 · Meta-analysis · Primary source
- Safety and Effectiveness of Oral Nutraceuticals for Treating Acne: A Systematic ReviewJAMA Dermatology, 2023 · Systematic review · Primary source
- Homeopathic Drug Products: Guidance for FDA Staff and IndustryU.S. Food and Drug Administration, 2022 · Health authority summary · Primary source
Page history
Show all 6 changes to this page
- — Rewritten to the content style guideline; ratings and sources unchanged.
- — Published. All six claims, the safety section and every source passed the site's source and wording reviews. Two uncited reviews and a GRADE-table inconsistency in one cited review stay logged in docs/08-open-decisions.md.
- — Added a note, quoted from the Office of Dietary Supplements, that the zinc upper limits count zinc from food and supplements. No rating changed.
- — Revised after the second source and wording review. The cold-prevention claim now covers colds only, not respiratory infections in general, because that is what the reviews pooled. A 2024 opinion article disputing the Cochrane cold review is now cited, and not counted toward any rating. No rating changed.
- — Revised after source and wording review. Preventing colds is now scoped to zinc taken by mouth and rated evidence against, by owner decision: the 2021 review's benefit for community-acquired infections came almost entirely from two nasal-spray trials. The macular degeneration heading now names progression to late disease, the page summary and 'what it is' section are attributed to their sources, and a sentence about a published critique of the Cochrane cold review is held back until the site can cite it.
- — First draft. Macular degeneration (in people who already have it) rated moderate; preventing colds, shortening colds, leg-ulcer healing, blood sugar control and acne rated limited.