Calcium magnesium & zinc supplement side effects

Updated April 17, 2017

Vitamins and minerals are important for everyday health. Most healthy individuals get enough of the recommended vitamins and minerals, including calcium, magnesium and zinc, through their diets, but there are times an additional supplement may be necessary. However, even over-the-counter supplements can cause unwanted side effects.


Calcium is an essential nutrient not produced by the body. It therefore must be ingested through diet or with supplements. Calcium helps regulate your heartbeat, stimulate hormone secretions, conduct nerve impulses, clot blood and build healthy bones. Although food is the best source of calcium, supplements are needed to reach the recommended daily allowance of 1,000 to 1,200 mg. Oral calcium supplements can cause minor side effects, including gas and constipation. To combat these effects, increase the amount of water you drink and add fibre to your diet, or change the type of calcium supplement you take. Calcium can be taken on its own or in a compound like calcium citrate, calcium phosphate or calcium carbonate; each may react differently in your body.


Magnesium supplements are usually not needed by healthy individuals. Most people get enough magnesium by eating green leafy vegetables, nuts and whole grains. However, when magnesium is depleted by illness, oral supplements may be taken. The recommended daily allowance for adults is 270 to 400 mg, depending on gender. Magnesium supplements can cause temporary diarrhoea, which usually resolves itself as the body adjusts to the supplements. In rare cases, side effects may include dizziness, flushing and difficulty breathing. If you experience any of these side effects, consult your doctor immediately.


Zinc is an important nutrient for overall health and growth. A zinc deficiency can result in poor vision, difficulty healing and an inability to fight infection. The recommended daily allowance of zinc is 12 mg for women and 15 mg for men. Zinc supplements are rarely associated with side effects, but occasionally you may experience chills, mouth ulcers, fever, heartburn, indigestion, nausea, sore throat or weakness. If these side effects remain or worsen over time, consult your doctor.

Supplement Overdose

Most people believe taking supplements and vitamins poses little health risk. Although the safety margin for vitamins is very high, they can cause unwanted side effects--and damage in high doses. Symptoms of overdose may include dizziness, fainting, shortness of breath and a slow or irregular heartbeat.


Calcium supplements can interfere with the absorption of the antibiotic tetracycline. Do not take calcium if you are taking this medication. Calcium also interferes with iron absorption; the two supplements should not be taken at the same time. High doses of calcium can lead to an increased risk of heart attack, according to a study at the University of Auckland in New Zealand.

Magnesium supplements may increase the symptoms of heart disease. Taking too much magnesium can lead to hypermagnesemia (too much magnesium in the blood), which can cause damage, especially for those with kidney disease. Zinc may not be absorbed well when taken with certain foods including bran, milk, poultry and whole grain breads and cereals. Do not take zinc supplements with copper, phosphorus or iron supplements. If you have a copper deficiency, consult your doctor. Taking zinc supplements may worsen this condition.

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About the Author

Stephanie Chandler is a freelance writer whose master's degree in biomedical science and over 15 years experience in the scientific and pharmaceutical professions provide her with the knowledge to contribute to health topics. Chandler has been writing for corporations and small businesses since 1991. In addition to writing scientific papers and procedures, her articles are published on and other websites.