Side Effects of Zinc Supplements: What Are They? | Evidence and WARNINGS

In the last few weeks I’ve had a slew of questions about Zinc. Can it help with Testosterone? (Yes!) Are there other benefits to Zinc? (Yes!) And recently, are there any Side Effects of taking too much Zinc? In this article we’ll tackle that last question, and let you know what the healthy parameters are for Zinc supplementation.

Quick Hits

  • Most Zinc toxicity reports start at the baseline of 50 mg, although this is also a common dose for people clinically deficient in Zinc.
  • Some side effects of too much Zinc mirror Zinc deficiency symptoms; if you have one of these symptoms, either track your diet or get tested.
  • Zinc Deficiency is far more dangerous than the side effects of too much Zinc.
  • Every supplement we’ve reviewed has safe Zinc levels for most consumers.

How Zinc Operates in Our Bodies

Zinc plays dozens of roles in our bodies, as I discussed in a previous article. From supporting our Immune System to helping us build proteins, it forms the basis of body processes we simply cannot live without. But because of how important it is, too much of it can override other important functions that need to take place.

Copper, Iron, and Magnesium Absorption

Because our bodies use the same metabolic functions to absorb nearly all minerals, if you take too much of any mineral you can’t absorb enough of the others. In fact, some hospital websites recommend taking a supplement of Copper or Magnesium, specifically, if you take a Zinc supplement.

Reduced Immune Function

I can already hear you. “Wait, Simon. I thought Zinc improved our Immune System?” It is counterintuitive, but medical scholarship is clear: too much Zinc hurts the Immune System almost as much as Zinc Deficiency.

Other Symptoms

The following are all clustered together in the literature for a few reasons. One is that they are not the direct consequence of too much Zinc, but the lack of other minerals, like Iron. Another reason is that they are only seen in cases where people take over 100 mg of Zinc per day, an instance so rare it isn’t well studied.

Lastly, related to that, it’s not ethical to intentionally give people something in doses that are known to harm them. So while we know the following are side effects of Zinc, we don’t have a lot of clinical literature documenting the mechanisms involved.

  • Nausea
  • Vomiting
  • Indigestion (cramps)
  • Diarrhea
  • Gastric hemorrhage


Next we have three known drug interactions to be aware of. While the problem is not necessarily with Zinc, it is important to keep in mind that dangerous side effects can and will occur if you’re not careful.

Antibiotics (quinolone and tetracycline)

Because of its involvement with the Immune System, the Zinc can keep these two specific types of Antibiotics from working. If your doctor prescribes Antibiotics and you’re taking Zinc, let your doctor know. This warning extends to antibiotic related medications such as the brands Cuprimine and Depen, used for Rheumatoid Arthritis.

Diuretics (thiazide)

Also known by its longer name, hydrochlorothiazide, this is a drug commonly given to help people pass water through their system to reduce inflammation. But Zinc can make the medication next to useless. If you’re given diuretics for a major condition, such as heart failure, tell your doctor immediately if you’re on a Zinc supplement.

Denture Adhesives

This may seem like it’s coming from pretty far afield, but the danger is real. According to the US Food and Drug Administration, the Zinc used in many Denture Adhesives can build up to toxic levels, resulting in nerve damage.

Safe Levels

Now that we know the risks, and other articles we’ve written have covered the benefits, what levels are safe for supplementation? According to medical experts, we should consume between 8 and 11 mg of Zinc per day from our diets.

But what if you want to supplement that intake with a T-Booster or other product? According to one database of safety, the Upper Limit of Zinc consumption for adults is 40 mg. But that’s based on how it impacts Copper absorption, not on any other side effects, which means in consultation with your doctor, you may go higher. 

For reference, the range of Zinc in T-Boosters that we’ve found are effective is between 10 mg and 40 mg per serving. And clinical doses range from 30 to 100 mg in studies and health literature.

Final Thoughts

The bottom line is that Zinc is far more beneficial than harmful. And if we take the doses of what is harmful into account, it is far more likely to run into deficiency issues than side effects.

Given those reasons, anyone considering taking a Zinc supplement should definitely take a food journal and map out how much they’re getting. If you have further questions, don’t hesitate to discuss them with your doctor, and be sure to bring up any medication concerns you have. And keep your diet balanced–too much Zinc may impair your other mineral absorption, which can raise issues all their own.

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About the Author

Sam is a passionate health and fitness enthusiast who has been interested in supplements, fitness, and wellness for over 10 years. He is the founder of Great Green Wall - the health and wellness brand and has completed multiple fitness certificates, including personal training and nutrition certifications. Sam has been working as a personal trainer for the past three years and is dedicated to helping his clients achieve their fitness goals and lead healthier lifestyles. He believes that a healthy lifestyle is crucial to a happy and fulfilling life and is committed to sharing his knowledge and passion with others.

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