Zinc Supplements: Benefits, Daily Dosage and Side Effects
Adults need 8 mg (women) to 11 mg (men) of zinc a day, and most people get that from food. A zinc supplement can help if your diet is low in zinc, if you're vegetarian, or if a doctor finds a deficiency. Keep total intake under the 40 mg daily upper limit, because long-term excess blocks copper absorption.
Evidence at a glance
| Use | Grade | What the research shows |
|---|---|---|
| Correcting zinc deficiency | A | Supplements reliably restore levels when intake or absorption is low. |
| Shortening the common cold (lozenges) | B | Some meta-analyses show shorter colds when started within 24 hours; results vary. |
| Preventing colds with daily pills | C | Not clearly supported in well-nourished adults. |
| Acne | C | Small trials suggest a modest benefit; less effective than standard treatments. |
A: strong, consistent human evidence · B: moderate · C: limited or mixed · D: good evidence of no benefit.
Zinc is a trace mineral, which means you need only a little of it, but it's involved in hundreds of processes: immune function, wound healing, DNA production, taste and smell. Your body can't store much zinc, so you need a steady supply from your diet, and sometimes from a zinc supplement.
What zinc does in the body
- Immune defense: Immune cells need zinc to develop and work properly. Even mild deficiency can weaken your response to infection.
- Wound healing: Zinc supports skin repair and collagen production.
- Growth and development: It's essential during pregnancy, childhood and adolescence.
- Taste and smell: Low zinc can dull both senses.
- Enzymes: More than 300 enzymes rely on zinc to function.
How much zinc do you need?
| Group | Recommended daily intake (RDA) |
|---|---|
| Men 19+ | 11 mg |
| Women 19+ | 8 mg |
| Pregnancy (19+) | 11 mg |
| Breastfeeding (19+) | 12 mg |
| Upper limit, adults (all sources) | 40 mg |
Unlike magnesium, whose limit covers supplements only, zinc's upper limit applies to food and supplements combined.
Who might need a zinc supplement?
Most people in high-income countries get enough zinc from food. You're more likely to run low if you:
- Eat a vegetarian or vegan diet. Plant foods contain phytates that reduce zinc absorption, so needs may be up to 50% higher.
- Have a digestive disorder such as Crohn's disease, ulcerative colitis or celiac disease, or have had weight-loss surgery
- Drink alcohol heavily
- Are pregnant or breastfeeding and eat few zinc-rich foods
- Are an older adult with a limited diet
- Have sickle cell disease
Best food sources
| Food | Serving | Zinc |
|---|---|---|
| Oysters, cooked | 3 oz | about 32 mg |
| Beef, cooked | 3 oz | about 4–5 mg |
| Crab, cooked | 3 oz | about 3 mg |
| Fortified breakfast cereal | 1 serving | about 3 mg (varies) |
| Pumpkin seeds | 1 oz | about 2 mg |
| Pork or chicken, cooked | 3 oz | about 2–3 mg |
| Chickpeas or lentils, cooked | ½ cup | about 1–1.5 mg |
Forms of zinc supplements
| Form | Notes |
|---|---|
| Zinc picolinate | Well absorbed in a small study; common in capsules |
| Zinc gluconate | Widely used, including in lozenges |
| Zinc citrate | Absorbed about as well as gluconate, less bitter |
| Zinc acetate | Common in cold lozenges |
| Zinc oxide | Cheap, absorbed less well |
Check the elemental zinc on the label. "50 mg zinc gluconate" contains only about 7 mg of zinc, while a label stating "Zinc (as picolinate) 25 mg" refers to elemental zinc.
Zinc for colds
Zinc lozenges have been studied for decades. Some meta-analyses found that lozenges providing about 75 mg of zinc per day, started within 24 hours of symptoms, shortened colds by roughly a third. Other reviews found smaller or inconsistent effects. If you try them:
- Start at the first sign of a cold
- Use them for no more than about a week
- Avoid nasal zinc sprays and gels. They have been linked to permanent loss of smell.
Side effects and risks
Short term, high doses can cause nausea, vomiting, stomach cramps, diarrhea and a metallic taste.
Long term, above 40 mg a day, zinc can:
- Cause copper deficiency, leading to anemia and nerve damage
- Lower "good" HDL cholesterol
- Weaken immune function, the opposite of what most people want
Medication interactions
- Antibiotics (quinolones and tetracyclines): zinc reduces absorption of both. Take the antibiotic at least 2 hours before or 4–6 hours after zinc.
- Penicillamine (used for rheumatoid arthritis and Wilson's disease): zinc reduces its effect.
- Thiazide diuretics: increase zinc loss in urine.
The bottom line
Most adults get the zinc they need, 8–11 mg a day, from food. A supplement makes sense if you're at higher risk of deficiency. Choose a moderate dose (15–25 mg), keep total intake under 40 mg per day, and don't take high doses for months without medical advice. For colds, lozenges started early may help a little; nasal zinc should be avoided.
Where to buy
Zinc picolinate or gluconate, 15–25 mg
Enough to fill a gap without approaching the 40 mg limit. Check the elemental zinc per capsule.
Zinc lozenges (acetate or gluconate)
Only useful if started within 24 hours of cold symptoms. Avoid nasal zinc products.
Frequently asked questions
Can you take zinc every day?
Yes, if your total intake from food and supplements stays at or below 40 mg a day. Long-term doses above that can cause copper deficiency, which leads to anemia and nerve problems.
What is the best time to take zinc?
Zinc is absorbed best on an empty stomach, but that often causes nausea. Taking it with a light meal is a practical compromise. Keep it a few hours apart from iron and calcium supplements and from certain antibiotics.
Does zinc help with colds?
Zinc lozenges started within a day of symptoms may shorten a cold slightly, though studies disagree. Taking zinc daily to prevent colds hasn't been clearly shown to work.
What are signs of zinc deficiency?
Slow wound healing, frequent infections, hair loss, loss of taste or smell, diarrhea and skin rashes can occur. These have many causes, so see a doctor rather than self-diagnosing.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.