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Zinc Side Effects, Overdose and Poisoning

Though zinc is important in facilitating many bodily functions, zinc side effects can occur if you do not take it as advised.

Do not get the wrong idea though, zinc is not medication, nor is it something you should avoid. In fact, you should always make sure that your diet includes proper amounts of zinc.

Zinc is an essential mineral that is needed by your body to manufacture about 300 enzymes. Each of these enzymes have diverse processes and functions such as cell reproduction, immunity, protein synthesis, wound repair, vision, free radical protection and immunity.

Zinc and Nutrition

Fortunately, a healthy daily diet can provide you with just enough zinc that you need. It is found in ordinary foods that we take such as red meat, sea foods and poultry. Oysters are the most excellent zinc sources. If you are not much into meats or seafood, other good sources include beans, whole grains, dairy products, cereals and nuts. However, zinc absorption is more effective if they come from animal proteins than from plant sources.Oyster

The Recommended Dietary Allowance of zinc varies, but generally about 9-11 milligrams is enough for adults. However, the truth of the matter is that only about 30% of the zinc that you intake can get absorbed by your body. Many factors can interfere with zinc absorption such as phytates in your brain and fibers. If your body cannot absorb as much as it needs, you may need to take zinc supplements in order to prevent zinc deficiency.

Who Needs Zinc Mineral Supplements?

To date, there is yet a laboratory test that can exactly measure how much zinc your body needs. But if you experience symptoms such as diarrhea, lesions, loss of appetite, growth retardation (in children), hair loss, delays in wound healing, taste abnormalities and so on, your doctor might suspect you to have some form of zinc deficiency. If so, he would most probably advise you to take zinc supplements.

Zinc supplements have also been seen to be effective in shortening cold symptoms, reduce the severity of cold sores, increase energy levels, treat ADHD in children, fighting hair loss and managing conditions such as hypoglycemia and diabetes.

Side Effects of Zinc Supplement

The danger of taking zinc supplements can be summarized in two words: zinc overdose. A zinc dose of 40 milligrams is approved safe to use by FDA and a zinc dosage more than this can pose certain risks.

In terms of zinc toxicity, there is no other way to put it: excess zinc is dangerous! This is primarily true because too much zinc will likely interfere with the metabolism and absorption of other essential minerals in your body, most especially iron, magnesium and copper. Zinc side effects can become potentially serious if you take doses from 150 to 450 mg a day. Taking this much can decrease your copper, iron and magnesium levels, reduce your body’s immune function, and reduce your HDL (good cholesterol) level.

Zinc Sulfate Side Effects

Oral zinc sulfate supplements can also cause side effects such as stomach upset, heartburn and nausea. Rare side effects have also been reported and these include fever, sore throat, mouth sores, weakness and fatigue.

Zinc is a very important mineral but you only need to take just enough. If you decide on taking mineral supplements for one or more reasons, it is very important that you consult your doctor first and report whatever zinc side effects you experience.

Zinc Poisoning in Humans


Full-fledged, acute zinc poisoning is a very rare event. Causing symptoms such as loss of appetite, nausea, vomiting, diarrhea, and destruction of white blood cells, zinc toxicity usually occurs when someone has drunk large quantities of an acidic beverage, such as orange juice, from a galvanized (zinc lined) container, releasing 800 to 2,000 mg of zinc per day, or more.

Fortunately, the symptoms of acute zinc poisoning usually abate within 24 to 72 hours of withdrawing the source of excess zinc from the diet.

Chronic nutritional imbalance caused by taking too much zinc is a relatively common problem. People who take 100 to 150 mg of zinc a day for several weeks to several months develop problems with the ways the body uses copper.

Zinc and Copper Reaction

In one case, a woman who took 400 mg of zinc a day became almost totally depleted of copper; her copper levels fell to 7 micrograms/dl, compared to an average of 70 to 155 micrograms/dl. She developed various zinc toxicity symptoms, especially neurological problems, including an unsteady gait, dizziness, and a low white blood cell count. She recovered a normal white blood cell count, but her central nervous system did not completely recover even after six months of avoiding zinc and taking copper.

So how can you avoid taking the wrong amount of zinc? Here are five recommendations to consider:

  1. If you take zinc, take copper, at least 1 mg but no more than 3 mg a day.
  2. Unless you have a medically diagnosed zinc deficiency, don’t take more than 40 mg of zinc a day.
  3. Get treatment for nasal symptoms quickly. Zinc nose sprays can cause permanent loss of sense of smell. However, people who suffer this complication usually experience intense pain after using a zinc nose spray to treat a cold. The pain is so bad that the user can’t stand up. If this happens to you after using a zinc nose spray, see a doctor at once. You may have a very short time to get medical treatment that may save your sense of smell.
  4. Get treatment for central nervous symptoms quickly, and stop taking zinc while you are waiting for your appointment, if you can’t see your doctor right away. Damage to the central nervous system caused by too much zinc depleting copper in the central nervous system can take months to correct.
  5. How Much Zinc is Too Much – If zinc tastes bad, you probably don’t need it. When your body is zinc-deficient, a zinc supplement will not leave a bitter or metallic aftertaste on your tongue. When your body has enough zinc, a zinc supplements will leave a bitter or metallic aftertaste on your tongue. If it tastes bad, don’t take it.

More About Zinc Overdose


Susan noticed she was beginning to wobble when she walked.

For some strange reason, she was not able to put one foot in front of another. After a few weeks, Susan found that she needed a cane to steady herself even to walk across a room in her home.

Making matters worse, Susan developed chronic sinus and ear infections. They were especially severe, and they did not cause a lot of inflammation, but after three months they did not go away. Once possessing a radiant complexion, she grew more and more pale.

A devoted follower of natural health, Susan had decided to stimulate her immune system with zinc. Instead of taking the recommended maximum of 30 milligrams a day for everyday use and 50 to 65 milligrams for up to three days with cold symptoms, Susan started taking 600 milligrams of zinc capsules each and every day. She felt it couldn’t be causing her any harm since she couldn’t even taste any bitter or metallic taste when she let the tablets dissolve in her mouth.

Zinc Overdose Symptoms

Zinc SymbolWhen Susan finally got to the doctor, she was diagnosed not with zinc overdose symptoms but as having an extreme copper deficiency. Too much zinc had displaced almost all the copper in her body, and without copper, her central nervous system had been unable to the enzymes it needs for the coordination centers in the brain. Her cholesterol levels had zoomed to very high levels and it appeared she was well on her way to becoming a diabetic-all because she took 10 times more than the highest recommended dosage of zinc every day and 100 times more than her body’s basic needs.

For Susan, the treatment was stopping zinc and starting copper, in her case, by intravenous injection. But people who take lower levels of zinc can also experience zinc toxicity and zinc supplement side effects.

Is Zinc Deficiency Common?

Dr. Ranjit Chandra, who was a pediatrician and immunologist at the Memorial University of Newfoundland, and who more recently formulated vitamin and mineral products for the Javaan Corporation in the United States, first addressed the problem of zinc overdoses when taking large amounts of zinc was popular, in the 1980’s, pointed out that zinc deficiency was (and is) a common nutritional problem in North America, especially among older adults.

Especially at risk are older adults who eat little or no meat but lots of whole grains and fiber. Zinc deficiencies can cause failures of thymus hormones, which are essential for the maturation of immune cells. A deficiency in zinc early in life can cause lifelong immune deficiency.

When people take as much as 300 milligrams of zinc a day, however, Dr. Chandra point out that immune function actually declines. The white cells known as macrophages, literally the “big eaters” are not attracted to bacteria and do not kill and consume them. Levels of LDL cholesterol go up not just in the bloodstream, but also inside cells.

If you have not taken so much zinc for so long that you also have a copper deficiency, however, treating zinc overdose is very simpleStop taking zinc. In as little as 24 hours, symptoms will begin to improve. And to ensure that your zinc supplements never cause overdose symptoms, make sure you get 3 milligrams (just 3!) of copper every day, to keep zinc and copper in balance.