The body uses zinc in enzyme activities that produce DNA and RNA, regulate immune system functions and repair cells. Reproduction and growth and the senses of smell and taste depend on this trace mineral. The recommended dietary allowances (RDA) provide safe daily amounts of zinc intake for adolescents and adults: for men and pregnant women, 15 mg; for women, 12 mg. Talk with your physician before taking zinc supplements, and seek medical care if you experience side effects.
Gastrointestinal Side Effects
The stomach and intestines break down oral supplements so the blood can deliver the nutrients to organs. Reactions to zinc can happen at any location along the digestive system and may include heartburn, indigestion, nausea, vomiting, abdominal cramps and diarrhea.
Taking zinc supplements may cause fever, chills, sore throat, weakness and fatigue. With higher doses of zinc, blood levels of infection-fighting white blood cells may decrease.
Urinary Tract Infections (UTIs)
Those with kidney disease should take low doses or skip supplementation, according to the National Institutes of Health. Zinc supplements in higher doses and over time may cause urinary tract infections and reduced ability to urinate. Men carry greater risk of UTIs from high-dose zinc supplementation because of the potential for prostate enlargement that constricts the flow of urine.
Overdose and Toxicity
A metallic taste in the mouth, vomiting and headaches may accompany a zinc overload. Acute reactions requiring medical treatment include chest pain, dizziness, fainting, shortness of breath, vomiting, and yellow eyes or skin. Long-term use of a high dose of zinc may produce chronic reactions--anemia, reduced immune function, reduced levels of HDL and urinary problems. Taking a high dose of zinc over 1 gm, or 100 mg per pound of body weight, could be fatal.
Interactions with Medications
Zinc interactions with two types of antibiotics (quinolones and tetracyclines) and a medication for rheumatoid arthritis (penicillamine) decrease the effectiveness of the medication and reduce absorption of zinc. The kidneys function to maintain appropriate levels of necessary nutrients in the bloodstream. Thiazide diuretics reduce zinc in the body by increasing zinc removal through the kidneys.