Background

Zinc is an essential trace element commonly found in red meat, poultry, and fish. It is necessary in small amounts for human health, growth, and sense of taste.

Zinc is found throughout the body. The body doesn't store excess zinc, so it must be obtained from the diet. It's needed for immune function, wound healing, blood clotting, thyroid function, and much more. It also plays a key role in maintaining vision and might have effects against viruses.

People commonly use zinc for zinc deficiency, diarrhea, and Wilson disease. Zinc is also used for acne, diabetes, anorexia, burns, and many other purposes. There is some scientific evidence to support its use for some of these conditions. But for most, there is no good scientific evidence to support its use. There is also no good evidence to support using zinc for COVID-19.

Safety Safety definitions

When taken by mouth: Zinc is likely safe when used in amounts no greater than 40 mg daily. It is possibly safe when taken in larger doses, especially when used only for a short period of time. But taking doses higher than 40 mg daily might decrease how much copper the body absorbs. Taking very high doses of zinc is likely unsafe and might cause stomach pain, vomiting, and many other problems. Single doses of 10-30 grams of zinc can be fatal.

When applied to the skin: Zinc is likely safe. Using zinc on broken skin may cause burning, stinging, itching, and tingling.

When inhaled: Zinc is possibly unsafe when inhaled through the nose. It might cause permanent loss of smell. Avoid using nose sprays containing zinc.

Special Precautions & Warnings:

Pregnancy: Zinc is likely safe when used in the recommended amounts while pregnant. But it is likely unsafe when used in high doses. Those over 18 should not take more than 40 mg of zinc daily, and those 14-18 years old should not take more than 34 mg daily while pregnant.

Breast-feeding: Zinc is likely safe when used in the recommended amounts while breast-feeding. But zinc is possibly unsafe when used in high doses. Those over 18 years old should not take more than 40 mg of zinc daily, and those 14-18 years old should not take more than 34 mg daily while breast-feeding.

Children: Zinc is likely safe when taken by mouth appropriately in recommended amounts. Daily doses of zinc should not exceed 4 mg daily in infants 0-6 months old, 5 mg daily in infants 7-12 months old, 7 mg daily in children 1-3 years old, 12 mg daily in children 4-8 years old, 23 mg daily in children 9-13 years old, and 34 mg daily in those 14-18 years old. In infants, it is possibly unsafe to apply topical zinc to broken skin. The zinc can be absorbed through the breaks in the skin and cause serious adverse effects.

Alcohol use disorder: Long-term, excessive alcohol use may reduce the body's ability to absorb zinc.

Surgery for weight-loss (bariatric surgery): Bariatric surgery reduces the absorption of zinc and might increase the risk for zinc deficiency. Zinc levels may need to be monitored.

Copper deficiency: Taking excess zinc can lead to copper deficiency. People with pre-existing copper deficiency or risk factors for copper deficiency such as malnutrition or gastrointestinal surgery may be at higher risk.

Kidney disease: Low intake of zinc in the diet might increase the risk of getting kidney disease. Also, people with kidney disease who are on hemodialysis are at risk for zinc deficiency and might require zinc supplements.

Vegetarianism: Vegetarian diets are often linked with lower zinc absorption. But the body adapts over time. It becomes better at absorbing zinc and reducing zinc loss.

Effectiveness

Dosing & administration

Zinc is an essential nutrient found in foods such as red meat, poultry, and fish. The amount that should be consumed on a daily basis is called the recommended dietary allowance (RDA). For females 18 years of age the RDA is 9 mg, and for females 19 years and older the RDA is 8 mg. For males 18 years and older the RDA is 11 mg. While pregnant, the RDA is 13 mg in those 18 years of age and 11 mg in those 19 years and older. While breast-feeding, the RDA is 17 mg in those 18 years of age and 12 mg in those 19 years and older. In children, the RDA depends on age.

Zinc is also available in supplements, lotions, gels, ointments, mouth rinses, and many other products. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.

Interactions with pharmaceuticals

Amiloride (Midamor)

Interaction Rating=Minor Be watchful with this combination.

Amiloride can increase the amount of zinc in the body. Taking zinc supplements with amiloride might increase zinc levels. But this isn't likely to be a big concern for most people.

Antibiotics (Quinolone antibiotics)

Interaction Rating=Moderate Be cautious with this combination.

Zinc might decrease how much antibiotic the body absorbs from the gut. Taking zinc along with quinolone antibiotics might decrease the effects of these antibiotics. To avoid this interaction, take antibiotics at least 2 hours before or 4-6 hours after zinc supplements.

Antibiotics (Tetracycline antibiotics)

Interaction Rating=Moderate Be cautious with this combination.

Zinc can decrease the amount of tetracyclines the body absorbs. Taking zinc with tetracyclines might decrease the effects of tetracyclines. To avoid this interaction, take tetracyclines 2 hours before or 4-6 hours after taking zinc supplements.

Atazanavir (Reyataz)

Interaction Rating=Minor Be watchful with this combination.

Atazanavir is a drug used for HIV infection. Zinc decreases how much atazanavir the body absorbs. But the body still absorbs enough atazanavir for it to work for treating HIV. So this interaction is probably not a big concern.

Cephalexin (Keflex)

Interaction Rating=Moderate Be cautious with this combination.

Zinc can reduce how much cephalexin the body absorbs. This might decrease how well cephalexin works for treating infections. To avoid this interaction, take zinc 3 hours after taking cephalexin.

Cisplatin (Platinol-AQ)

Interaction Rating=Moderate Be cautious with this combination.

Cisplatin is used to treat cancer. Taking zinc along with cisplatin might inactivate cisplatin therapy. But it's not clear if this is a big concern.

Medications for HIV/AIDS (Integrase inhibitors)

Interaction Rating=Moderate Be cautious with this combination.

Taking zinc along with integrase inhibitors might decrease blood levels of integrase inhibitors. This might decrease the effects of these medications. Talk to your healthcare provider if you are using integrase inhibitors and want to start taking zinc.

Penicillamine (Cuprimine, Depen)

Interaction Rating=Moderate Be cautious with this combination.

Zinc might decrease how much penicillamine the body absorbs. Taking zinc with penicillamine might decrease the effects of penicillamine. Take zinc and penicillamine at least 2 hours apart.

Ritonavir (Norvir)

Interaction Rating=Moderate Be cautious with this combination.

Ritonavir is a drug used for HIV infection. Zinc can reduce how much ritonavir the body absorbs. But it isn't clear if this is a big concern.

Interactions with herbs & supplements

Beta-carotene: High doses of zinc can lower beta-carotene blood levels.
Bromelain: Zinc might reduce the effects of bromelain. But this isn't likely to be a big concern.
Calcium: Calcium supplements might decrease how much zinc the body absorbs from food. This usually doesn't seem to be much of a problem. But this interaction can be avoided by taking calcium supplements at bedtime instead of with meals.
Chromium: Taking chromium and zinc together can reduce the absorption of both chromium and zinc. This is probably not a big concern with usual doses of zinc and chromium.
Coffee: Taking zinc with coffee can reduce how much zinc the body absorbs.
Copper: Large amounts of zinc can reduce copper absorption. Taking zinc in high doses can cause copper deficiency and anemia. Some signs of copper deficiency have also occurred in people taking zinc in doses of 150 mg daily or more for 2 years.
EDTA: EDTA is a chemical compound that is given to people to remove excess metals from the body, especially lead. Repeated high doses of EDTA, as used in chelation treatment, can reduce blood zinc levels by up to 40%. People receiving chelation therapy should be monitored for zinc deficiency.
Folic acid: Folic acid supplements can change the absorption of zinc from food. But normal supplemental doses of folic acid are not likely to affect zinc levels in people with adequate dietary zinc intake.
IP-6 (Phytic acid): Phytic acid found naturally in foods can bind zinc and reduce how much is absorbed by the body. Avoid IP-6 supplements, which contain phytic acid, if you have other risk factors for zinc deficiency.
Iron: Iron and zinc can interfere with each other's absorption. To avoid this effect, take these supplements with food.
Magnesium: High doses of zinc supplements (142 mg/day), or high zinc intake from foods (53mg/day), seems to decrease magnesium levels. But it isn't clear if this is a big concern.
Manganese: Research suggests zinc supplements can increase the amount of manganese absorbed from supplements.
Riboflavin (Vitamin B2): Research suggests riboflavin can improve zinc absorption. The importance of this isn't known.
Vitamin A: Zinc supplements can increase blood levels of vitamin A. Zinc might increase the effects and side effects of vitamin A.
Vitamin D: Vitamin D is involved in zinc absorption, but it's not clear whether vitamin D improves zinc absorption.

Interactions with foods

Taking zinc with coffee can reduce how much zinc the body absorbs.

Eating foods containing fiber and phytates, which are chemicals found in grains such as maize, corn, and sorghum, can also reduce how much zinc the body absorbs. But the body usually adapts over time. Eating animal protein can increase zinc absorption, while plant proteins such as soy might reduce absorption.