B Complex and Zinc Together: Side Effects

Quick answer

NIH describes no effect of a B complex on zinc, and the two are routinely combined in multivitamins. Adults need 8 to 11 mg of zinc a day, with an upper limit of 40 mg. The side effects that come with each group differ, so they are easy to tell apart.^1,2,3

Key facts

Adults need 11 mg of zinc a day for men and 8 mg for women. The upper limit is 40 mg a day from all sources.^1,2
Almost all multivitamin and mineral supplements contain zinc, and B complex vitamins also appear in most multivitamins.^1,3
Phytates in beans, whole grains and seeds bind zinc in the gut, so meals rich in them release less zinc.²
Zinc at 50 mg a day or more for weeks can block copper absorption. B vitamin limits are 35 mg for niacin, 100 mg for B6 and 1,000 mcg for folic acid.^2,4
Quinolone and tetracycline antibiotics can bind zinc, and the labels for ciprofloxacin, levofloxacin and tetracycline list zinc among the products that reduce their absorption.^5,6

What the sources say about taking them together

People ask this because the two are so often sold in one bottle. A multivitamin and mineral supplement usually has zinc, and a multivitamin usually has the B vitamins. We looked for any statement that a B vitamin changes how zinc is absorbed or the reverse. The NIH fact sheets for zinc and for the B vitamins contain none, and we found no trial that tested the two together.^1,3

Almost all multivitamin and mineral supplements contain zinc.¹

A B complex supplement combines several B vitamins in one product. The same vitamins are also sold one at a time and appear in most multivitamins.^3,7,8

The better-documented effects on zinc absorption come from elsewhere in the meal. The share absorbed from food ranges from 5% to more than 50% depending on how much phytate the diet contains, and a supplement with 25 mg of iron or more can reduce zinc absorption.^2,9

What each is graded for

Provides B vitamins that contribute to normal energy-yielding metabolism*^{10,11,12,13,14}

Moderate evidence

Thiamin, riboflavin, niacin, pantothenic acid, vitamin B6, vitamin B12 and biotin are needed by the enzymes that release energy from food; niacin alone is part of a coenzyme used by more than 400 enzymes. 'Contributes to normal energy-yielding metabolism' is the wording European regulators permit for each of these vitamins. It does not mean extra B vitamins give more energy to someone who already gets enough.

Amount studied: Recommended daily amounts of each B vitamin, from food and supplements together

Helps you reach the recommended daily zinc intake when food falls short*^1,2,15

Moderate evidence

Most people in the United States get enough zinc from food, but national survey data from 2005 to 2016 show that 15% of adults take in less than the estimated average requirement. Teenage girls (20.9% below it), older adults, people who are pregnant and people who eat no meat are more likely to fall short. NIH says people who follow vegetarian or vegan diets might benefit from zinc supplements.

Amount studied: Recommended intake: 11 mg a day for men and 8 mg for women, from food and supplements

Contributes to normal protein and DNA synthesis, and has a role in cell division*^1,2,16

Moderate evidence

A well-established nutrient function. NIH describes zinc as part of protein and DNA synthesis and of cell signaling and division, and as needed for normal growth during pregnancy, childhood and the teen years. EU regulators permit matching statements for foods that are at least a source of zinc.

Amount studied: Recommended intake: 11 mg a day for men and 8 mg for women, from food and supplements

Telling the side effects apart

A practical use of the two sets of sources is sorting out which supplement caused what. NIH describes distinct complaints for each group, summarized below. If the same symptom appears with both, the amounts are the first thing to check.^2,11,13

Which complaint belongs to which^2,8,11,13,15
What you notice	Documented with
Red, warm, itchy skin on the face, arms and chest, often within 30 minutes	Niacin as nicotinic acid, typically from about 30 to 50 mg
Bright yellow urine	Riboflavin, which is yellow
A metallic taste in the mouth	High intakes of zinc
Nausea, stomach cramps, loss of appetite or headache	Too much zinc; nausea is also listed for very high amounts of vitamin B6 or niacin
Painful skin patches or sensitivity to sunlight	Too much vitamin B6

None of these is a way to diagnose anything. They are the effects the sources link to high amounts, and a doctor or pharmacist is the right person to ask if one persists.²

Amounts and our products

Zinc and the B vitamins with limits, for adults per day^1,4,17,18
	Recommended	Upper limit
Zinc	8 mg (women), 11 mg (men)	40 mg from all sources
Niacin	14 mg NE (women), 16 mg NE (men)	35 mg from supplements and fortified foods
Vitamin B6	1.3 mg at ages 19 to 50	100 mg
Folate	400 mcg DFE	1,000 mcg of folic acid

What’s in ours

Men's Multi: Zinc, 15 mg per serving, from the label
Immune Support: Zinc, 11 mg per serving, from the label

What’s in ours

Men's Multi: Vitamin B1, 7 mg per serving, from the label

Our Men's Multi carries both zinc and a set of B vitamins. One other product of ours also has zinc, along with vitamin B6. Because the zinc limit counts every product, the label amounts are what to add up.

Copper, medicines and who should ask first

Taking 50 mg of zinc a day or more for weeks can block copper absorption and lower copper status, which is why the adult upper limit is 40 mg from all sources. B complex products carry no matching mineral caution, but their own limits apply to niacin, vitamin B6 and folic acid.^1,2,4

The upper limit for adults is 40 mg of zinc a day from all sources: food, drinks, supplements and medicines, including during pregnancy and breastfeeding. It is 34 mg for teens aged 14 to 18 and lower for children. It is set to protect copper status and does not apply to people given zinc as medical treatment by a doctor.^1,2

Your doctor may want to check on you

Thiazide diuretics such as hydrochlorothiazide and chlorthalidone increase the zinc lost in urine, and taking them for a long time might lower the body's zinc.^1,2

Reported in studies

Ask first if you take a quinolone or tetracycline antibiotic, penicillamine or a thiazide water pill, which interact with zinc.¹
Ask first if you plan to take more than 40 mg of zinc a day.²
Ask first if you take methotrexate, an anti-seizure medicine, metformin or a medicine that lowers stomach acid, which have cautions with B vitamins.^3,19
Ask first if you use zinc-containing denture cream every day.¹
Ask first if you are pregnant, planning a pregnancy or breastfeeding.²

Questions people ask

Can you take B complex and zinc together?

The NIH sheets for the two groups describe no effect of one on the other. Add up the zinc from every product against the 40 mg limit, check the niacin, B6 and folic acid totals, and ask a pharmacist about antibiotics.^2,3,4

Can you take B complex with zinc at the same time of day?

Neither source names a time of day. Meals rich in phytate release less zinc, and nicotinic acid flushes less with food, so in our sources the content of the meal says more than the hour.^2,11

Does zinc cause nausea?

It can at high intakes. NIH lists nausea, vomiting, loss of appetite, stomach cramps, diarrhea and headaches among the effects of too much zinc, with a metallic taste as another sign.^1,2,15

Will a B complex lower my zinc?

No source we read says so. The documented ways to lower zinc absorption are phytate in food and iron supplements of 25 mg or more taken at the same time.^2,9

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.