Can You Take Too Much Zinc? Signs, Limits and the 50 mg Line

Yes, you can take too much zinc, and the UK line is clear: the NHS says "Do not take more than 25mg of zinc supplements a day unless advised to by a doctor."¹ Adults need about 9.5 mg a day for men and 7 mg for women.¹ Too much in one go means nausea, cramps and vomiting, worst on an empty stomach. Too much for months is the quieter problem: "Taking high doses of zinc reduces the amount of copper the body can absorb. This can lead to anaemia and weakening of the bones."¹ So 50 mg a day is too much for routine use without a doctor and 25 mg is the ceiling. This page sits under the Wellgard zinc guide, next to how much zinc a day.

How much zinc is too much?

Three assessments set the UK numbers.^{1, 2, 3}

The EVM is the UK Expert Group on Vitamins and Minerals (2003) and the SCF the EU Scientific Committee on Food (2003). The EVM figure is for supplements on top of food, which it put at a mean of 9.8 mg a day; the EU figure is for everything. Other countries set higher limits.^{2, 3}

Is 50 mg of zinc too much?

For daily use without a doctor, yes. Healthy men on two 25 mg doses a day for six weeks kept their plasma copper, but the copper-dependent enzyme in their red cells fell, significantly by week six.⁴ Women on 50 mg a day for ten weeks lost ferritin, haematocrit and the same enzyme; adding 50 mg of iron protected their iron but not their copper.⁵ The EVM took 50 mg as the lowest effect dose and halved it for safety to reach 25 mg.² One 50 mg tablet is not an emergency; a 50 mg habit is a reason to step down inside the 25 mg line. Do not add copper to "balance" it: neither assessment recommends a ratio, and the NHS puts copper's own ceiling at 10 mg a day from all sources (see zinc and copper).^{1, 2, 3}

Is 30 mg too much? It is above the NHS supplement line, so not for daily use without advice. Nineteen young men took 30 mg a day, about 40 mg with food, for 14 weeks with no change in copper status or blood counts; the EVM also records one person who took 26.6 to 40 mg a day for at least two years and developed copper deficiency and anaemia.^{2, 3}

What are the signs of too much zinc?

Within hours. The SCF lists "nausea, vomiting, epigastric pain, abdominal cramps and diarrhoea"; the EVM adds lethargy and dizziness.^{2, 3} In a six-week trial of 150 mg a day, 84% of the women and 18% of the men reported headaches, cramps, nausea, loss of appetite or vomiting, particularly "when small meals or no food was taken with the supplements".^{2, 6} Constipation is not an effect these sources record for zinc; in a multi-mineral product the iron is the usual suspect, and the NHS lists constipation among the common side effects of ferrous sulfate.⁷

Over months. This is copper deficiency, and it does not feel like zinc: anaemia, low white cell counts, more infections, then numbness and tingling in the feet and hands and an unsteady walk.^{2, 3, 8, 10} In 55 published cases of copper deficiency myelopathy, the risk factors were previous upper gastrointestinal surgery, zinc overload and malabsorption; the picture mimics vitamin B12 deficiency, and recovery after copper was partial.⁸ The denture-cream cases show the extreme: a 50-year-old man in the UK had four years of unsteadiness and falls, with anaemia and undetectable caeruloplasmin, from heavy use of a zinc-containing fixative. His bone marrow recovered within three months of switching fixative and taking copper; his nerves did not.^{9, 10}

Not a sign. No eye or nail change from excess appears in these assessments or reports, and a blood test is a poor guide: plasma holds about 0.1% of the body's zinc, so a raised result mostly reflects recent intake.³

How do people end up over the line?

Two routes. The first is a single high-strength tablet, often 50 mg, on an empty stomach. The second is stacking: a 50 mg tablet, plus a multivitamin giving 10 mg, plus a vitamin C and zinc product giving 15 mg, is 75 mg a day from supplements, three times the NHS ceiling, before the roughly 10 mg a typical diet adds.^{1, 2} Even without the tablet, the multivitamin and the vitamin C pairing make 25 mg between them. Read the elemental figure: UK labels state zinc itself, not the salt; in the trial above "50 mg of elemental zinc" came as 220 mg of zinc sulphate.⁶ Lozenges for colds are covered at does zinc help with colds and the commonest pairing at vitamin C and zinc together; a meal is the simplest way round the nausea, see when is the best time to take zinc.

Who should not take zinc without asking first?

• Diabetes: 50 mg a day for 28 days raised HbA1c in a small study of people with insulin-dependent diabetes, enough for the EVM to call them vulnerable. Haemochromatosis: enhanced absorption of several metals and "insufficient data" on a safe level.²
• Previous stomach or bowel surgery, or a condition that impairs absorption: the risk factors in the myelopathy cases.^{3, 8}
• Wilson's disease: zinc is used as a treatment to block copper, so the dose belongs to the specialist.²
• Pregnancy and breastfeeding: the 25 mg upper level applies unchanged; ask a GP or midwife first.³
• Children: the NHS gives no supplement figure for children; ask a pharmacist, GP or health visitor.¹
• Anyone on medicines. For ciprofloxacin the NHS says "Leave 2 hours in between taking supplements and your dose of ciprofloxacin tablets or liquid."¹¹ Tetracycline antibiotics and penicillamine also interact; see what should you not take with zinc.

Low zinc has its own page, signs of zinc deficiency; the other minerals sit in the vitamins and minerals guide; and vitamin D at can you take too much vitamin D.

What should you do if you think you have taken too much?

One large dose and you feel sick. Stop, eat something, and sip fluids. The NHS says to call 111 if you "keep being sick and cannot keep fluid down" or have blood in your diarrhoea, and to call 999 or go to A&E if you "vomit blood or have vomit that looks like ground coffee", have "a sudden, severe tummy ache", or are "confused or not responding as usual".¹²

A child has swallowed tablets. The NHS poisoning advice is to "Call 999 or go to A&E if you think you, a child, or someone else may have swallowed, touched or breathed in something harmful", to call 111 if you are not sure, to take the packaging, and not to try to make them sick.¹³

Months at 50 mg or more, and you are tired, tingling, unsteady or catching everything. Stop the zinc and see your GP. The tests are a full blood count, serum copper and caeruloplasmin, and B12, because the two deficiencies look alike and the UK patient was given B12 injections first, to no effect.^{8, 10}

Frequently asked questions

Do you pee out excess zinc, or does it build up?

Neither, mostly. "Zinc is not stored in the body and excess intakes result in reduced absorption and increased excretion", the SCF says, and the EVM notes excretion is "largely via the faeces".^{2, 3} That does not undo the copper block at 50 mg and above, which happens every day the dose is taken. Stopping is the fix.

Can too much zinc kill you?

Not at shelf doses taken as directed. Acute toxic effects begin at around 200 mg, and a dose large enough to cause vomiting is put at 225 to 450 mg.^{2, 3} The serious harm on record is slow: copper deficiency over months to years, partly irreversible in the nerves.^{8, 10}

Is 20 mg of zinc a day too much?

No. It is inside the NHS 25 mg supplement line, provided it is the only zinc product you take; add a 10 mg multivitamin and you are at 30 mg. Take it with a meal if it makes you queasy.^{1, 2}

Sources

1. NHS. Vitamins and minerals: others (zinc and copper). nhs.uk.
2. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals, 2003: zinc, pp 253-262. UK Government Web Archive.
3. Scientific Committee on Food. Opinion on the tolerable upper intake level of zinc, 2003, in Tolerable Upper Intake Levels for Vitamins and Minerals (EFSA, 2006), pp 191-201. efsa.europa.eu.
4. Fischer PW, et al. Effect of zinc supplementation on copper status in adult man. American Journal of Clinical Nutrition, 1984. PubMed 6486080.
5. Yadrick MK, et al. Iron, copper, and zinc status: response to supplementation with zinc or zinc and iron in adult females. American Journal of Clinical Nutrition, 1989. PubMed 2912000.
6. Samman S, Roberts DC. The effect of zinc supplements on plasma zinc and copper levels and the reported symptoms in healthy volunteers. Medical Journal of Australia, 1987. PubMed 3547053.
7. NHS. Side effects of ferrous sulfate. nhs.uk.
8. Jaiser SR, Winston GP. Copper deficiency myelopathy. Journal of Neurology, 2010. PubMed 20232210.
9. Nations SP, et al. Denture cream: an unusual source of excess zinc, leading to hypocupremia and neurologic disease. Neurology, 2008. PubMed 18525032.
10. Barton AL, et al. Zinc poisoning from excessive denture fixative use masquerading as myelopolyneuropathy and hypocupraemia. Annals of Clinical Biochemistry, 2011. PubMed 21525151.
11. NHS. Taking or using ciprofloxacin with other medicines and herbal supplements. nhs.uk.
12. NHS. Diarrhoea and vomiting. nhs.uk.
13. NHS. Poisoning. nhs.uk.

This article is general information, not medical advice. Do not take more than 25 mg of zinc from supplements a day unless a doctor has advised it, and see your GP if you have been taking more for months.