Zinc is an essential mineral needed for immune function, wound healing, taste and smell, and growth. Supplements are taken for deficiency, colds, acne, and diarrhoea in children — where it has strong evidence. Long-term high doses cause copper deficiency, so more is not better.
What is Zinc?
Zinc is a trace mineral. The body needs only small amounts, but it is a co-factor for hundreds of enzymes and is structurally essential to many proteins, so a shortage shows up in several systems at once.
Its main roles:
- Immune function — zinc is needed for immune cells to develop and work.
- Wound healing and skin integrity.
- Taste and smell — loss of either is a classic sign of deficiency.
- Growth and development, which is why deficiency matters most in children.
- Protein and DNA synthesis.
- Male reproductive health, including testosterone metabolism.
The body has no meaningful zinc store, so intake needs to be regular. Dietary sources are mainly animal foods — meat, shellfish, dairy — plus legumes, nuts and whole grains.
Deficiency is more common in South Africa than people assume, particularly on maize-based diets. Maize is high in phytates, which bind zinc and reduce absorption, so intake can look adequate while absorption is not. Vegetarians, people with malabsorption conditions, and people with chronic diarrhoea are also at higher risk.
What is Zinc commonly used for?
- Diagnosed zinc deficiency.
- Childhood diarrhoea, where zinc is a WHO-recommended treatment alongside oral rehydration solution — it shortens the episode and reduces the chance of another in the following months. This is its best-evidenced use.
- Colds, where zinc lozenges started within about 24 hours of symptoms may shorten the illness modestly.
- Wound healing, including pressure sores and ulcers, where deficiency is present.
- Acne, where it is sometimes used as an adjunct.
- Loss of taste or smell, if caused by deficiency.
- Age-related macular degeneration, as part of a specific formulation used under supervision.
- Growth faltering in children, where deficiency contributes.
Childhood diarrhoea is the use worth knowing about. Alongside oral rehydration solution, zinc for 10 to 14 days reduces how long the episode lasts and how severe it is, and lowers the risk of further episodes over the next few months. Rehydration remains the priority — zinc supports it rather than replacing it. If a child has diarrhoea, ORS is the treatment that prevents harm; ask a pharmacist or clinic about zinc alongside.
Be realistic about colds. The evidence suggests a modest shortening of symptoms if lozenges are started very early and taken frequently. It does not prevent colds, and starting on day three achieves little.
Who commonly looks for Zinc and why
- Parents of a child with diarrhoea.
- People wanting to support immunity, particularly in winter or around a cold.
- People with acne.
- People with slow-healing wounds, or after surgery.
- People who have lost taste or smell.
- Vegetarians and vegans, where absorption from plant sources is lower.
- Men looking at testosterone or fertility claims.
- People with chronic diarrhoea, coeliac disease or inflammatory bowel disease.
- People with diabetes or chronic kidney disease, where losses can be higher.
What to check on the label before taking Zinc
Check the elemental zinc amount, not the compound weight. This is the single most confusing thing on a zinc label. “Zinc gluconate 50 mg” does not mean 50 mg of zinc — the elemental content is a fraction of that, and it differs by salt (gluconate, sulfate, citrate, picolinate). A good label states elemental zinc; if yours does not, ask a pharmacist rather than guessing.
Add up every product you take. Zinc appears in multivitamins, immune formulas, cold remedies and men’s health products. Stacking is how people reach amounts that cause copper deficiency.
Take it with food if it upsets your stomach, though absorption is somewhat better on an empty stomach.
Separate it from certain medicines by at least two hours — zinc binds them and reduces absorption:
- Antibiotics — ciprofloxacin and other quinolones, and tetracyclines such as doxycycline.
- Iron supplements, which compete with zinc.
- Calcium supplements and antacids.
Speak to a pharmacist or doctor if:
- The supplement is for a child — the amount is weight- and age-dependent.
- You take antibiotics, iron or calcium — ask about spacing.
- You have chronic kidney disease.
- You are pregnant or breastfeeding.
- You are taking it long term, where copper needs consideration.
- You have persistent diarrhoea, unexplained weight loss, or slow-healing wounds that have not been assessed.
Safety, interactions and when to seek professional advice
Long-term high-dose zinc causes copper deficiency, and this is the caution that matters. Zinc and copper compete for absorption. Sustained high zinc intake blocks copper uptake, and copper deficiency causes anaemia, low white cell counts, and — importantly — neurological damage including numbness, unsteadiness and difficulty walking, which may not fully reverse.
This is not a theoretical risk; it is a recognised consequence of taking high-dose zinc for months, and it is easy to reach by combining several products. If you take zinc long term, keep to sensible amounts and mention it to your doctor.
Nausea is the commonest short-term effect, particularly on an empty stomach. A metallic taste, stomach cramps and diarrhoea also occur.
Do not use intranasal zinc products. Zinc nasal sprays and gels have been associated with permanent loss of smell and were withdrawn in several markets. Lozenges taken by mouth are a different matter.
Zinc does not treat a cold you already have well established, and it does not prevent infection in someone who is not deficient.
Persistent symptoms need diagnosis. Slow wound healing, chronic diarrhoea, loss of taste or smell, or recurrent infections should be assessed rather than supplemented indefinitely — several causes are treatable, and diabetes in particular presents this way.
Seek medical attention for numbness, tingling or unsteadiness developing on long-term zinc; unexplained anaemia or repeated infections; diarrhoea in a child that is not settling or with signs of dehydration; wounds that are not healing; or loss of taste or smell that persists.
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Frequently asked questions
What is zinc used for? Immune function, wound healing, taste and smell, and growth. Supplements are used for deficiency, childhood diarrhoea, colds and acne.
Does zinc help with colds? Lozenges started within about 24 hours may shorten symptoms modestly. It does not prevent colds, and starting late achieves little.
Why is zinc given for diarrhoea in children? Alongside oral rehydration solution, zinc shortens the episode and reduces the risk of further episodes over the following months. Rehydration remains the priority.
How much zinc is in my tablet? Check the elemental zinc, not the compound weight. “Zinc gluconate 50 mg” contains far less than 50 mg of actual zinc.
Can I take too much? Yes. Sustained high intake blocks copper absorption, causing anaemia and nerve damage that may not fully reverse. Add up every product you take.
Can I take it with my antibiotics? Separate them by at least two hours. Zinc binds quinolone and tetracycline antibiotics and reduces their absorption.