Taking in too much zinc, whether from supplements or other products, can cause side effects, including digestive issues, changes to your sense of taste, and copper deficiency.
Zinc is an essential mineral involved in over 100 chemical reactions in your body.
It’s necessary for growth, DNA synthesis, and taste perception. It also supports wound healing, immune function, and reproductive health (
Health authorities have set the tolerable upper intake level (UL) for zinc at 40 milligrams (mg) per day for healthy adults ages 19 and above. The UL is the highest recommended daily amount of a nutrient. For most people, this amount is unlikely to cause negative side effects (
Food sources high in zinc include meat, fish, seafood, and certain fortified cereals. Oysters contain the highest amount, with up to 291% of the daily value in a 3-ounce serving (
Although some foods can provide amounts well above the UL, there are no reported cases of zinc poisoning from zinc that naturally occurs in food (2).
However, zinc poisoning can occur from dietary supplements, including multivitamins, or accidental ingestion of zinc-containing household products. High amounts of zinc are also found in some denture adhesive creams (
Toxic amounts of zinc can be absorbed in other ways, including skin exposure and inhalation. Dangerous levels of zinc exposure may be possible in certain industrial jobs, such as metalworking.
Zinc poisoning may look different depending on how much of the mineral you consumed and whether you consumed it in a short amount of time or over a longer period.
Here are 7 potential signs and symptoms of zinc overdose.
Nausea and vomiting are common side effects of zinc toxicity.
A 2012 review of 17 studies on the effectiveness of zinc supplements for treating the common cold found that zinc may have reduced the duration of a cold, but adverse effects were common. In fact, the review found that study participants receiving zinc had a 64% higher risk of nausea than people in the control groups (
If you think you may have consumed toxic amounts of zinc, get emergency medical help.
Vomiting does not mean your body can “get rid” of toxic amounts of zinc. Medical care is still needed to treat zinc toxicity and prevent further complications.
When someone has consumed a toxic amount of zinc, it may also cause them to have blood in their vomit (
Blood in your vomit can sometimes look like coffee grounds. Vomiting blood is a serious condition that requires immediate medical attention.
Nausea and vomiting are common and often immediate reactions to ingesting toxic amounts of zinc. Zinc toxicity requires emergency medical care.
Zinc poisoning can also cause stomach pain and diarrhea. Someone who has swallowed a toxic amount of zinc may also experience watery diarrhea (
When harmful amounts of zinc are consumed, gut irritation and gastrointestinal bleeding can occur.
If you notice signs of bleeding in your gut, such as bloody vomit or black and tarry feces, it’s important to get medical help right away.
Stomach pain and diarrhea are common symptoms of zinc toxicity. In some cases, severe gastrointestinal damage and bleeding can occur.
Zinc exposure can happen in industrial workplaces, particularly those that involve metalworking. Examples include welding, soldering, and alloy production. It’s possible for workers who breathe in certain metal fumes to inhale toxic amounts of zinc (
Inhaling zinc fumes can cause flu-like symptoms, such as fever, chills, cough, headache, and fatigue (
These symptoms occur in many conditions, including other mineral toxicities. As a result, diagnosing zinc toxicity can be difficult (5).
Your doctor may need your detailed medical and dietary history and blood tests for suspected mineral toxicity.
If you work in a location where you could be exposed to zinc, be sure to disclose this to your healthcare professional.
Flu-like symptoms can occur due to toxic inhalation of several minerals, including zinc. If your job involves metalworking or other potential zinc exposures, tell your doctor.
HDL (good) cholesterol lowers your risk of heart disease by clearing cholesterol from your cells. This prevents the buildup of artery-clogging plaque.
For adults, health authorities recommend an HDL greater than 40 milligrams per deciliter (mg/dL) for males and 50 mg/dL for females. Lower levels put you at a higher risk of heart disease (
Research suggests that taking zinc in amounts higher than the UL may have effects on the body that lead to low HDL (
However, some studies also suggest that zinc supplements may improve cholesterol levels in people who have health conditions such as obesity or diabetes. Taking zinc in standard, nonexcessive amounts was shown to lower LDL (bad) cholesterol and raise HDL (good) cholesterol (
In general, though, high doses of zinc are reported to have a negative effect on HDL cholesterol.
While several factors affect cholesterol levels, these findings are something to consider if you take zinc supplements regularly.
If you have health conditions, it’s important to talk with your doctor about whether these supplements are appropriate for you.
Regular ingestion of zinc above the recommended levels can cause a drop in HDL (good) cholesterol levels, which may put you at a higher risk of heart disease.
Zinc is important for your sense of taste. In fact, zinc deficiency can result in hypogeusia, a dysfunction in your ability to taste (
Zinc supplements, especially lozenges and syrups, can cause a bad taste in your mouth. This symptom has been reported in studies investigating zinc supplements for treating the common cold (
Some studies suggest that zinc supplements may shorten the time it takes to get over the common cold. However, caution is needed if you decide to try this approach. The dose of zinc you get from certain cold remedies may be above the UL of 40 mg per day. Plus, adverse effects are common (
Because zinc supplements and remedies may contain more zinc than the recommended UL, it’s important to talk with your doctor before trying them.
Zinc plays a role in taste perception. Zinc supplements may cause a bad taste in your mouth, particularly when taken as a lozenge or liquid supplement.
Doses of zinc above the established UL can interfere with your body’s ability to absorb copper. Over time, this can cause copper deficiency (2).
Copper is an essential mineral. It aids in iron absorption and metabolism, making it necessary for red blood cell formation. It also plays a role in white blood cell formation (
Red blood cells transport oxygen through your body, while white blood cells are key to your immune function.
Zinc-induced copper deficiency is associated with several blood disorders (
- Iron deficiency anemia: a lack of healthy red blood cells due to insufficient amounts of iron in your body
- Sideroblastic anemia: a lack of healthy red blood cells due to an inability to metabolize iron properly
- Neutropenia: a lack of healthy white blood cells due to a disruption in their formation
If you taking copper supplements or have a health condition associated with copper deficiency, talk with your doctor before taking zinc.
Regular doses of zinc above 40 mg per day can block copper absorption. This can result in copper deficiency, which is associated with several blood disorders.
Zinc plays an important role in immune system function, and zinc deficiency can affect its function. However, too much zinc may suppress your immune response (
In test-tube studies, excess zinc reduced the function of T cells, a type of white blood cell. T cells play a key role in your immune response by attaching to and destroying harmful pathogens (
This means that too much zinc may reduce your body’s ability to fight infections (
Taking zinc supplements in doses above the UL may suppress your immune response, leaving you more susceptible to illness and infections.
If you believe you may be experiencing zinc poisoning, contact your local poison control center immediately.
Zinc poisoning is potentially life threatening. It’s important to seek medical help right away.
In many cases, doctors can treat zinc poisoning with supportive care. Medications can help manage symptoms and reduce the amount of zinc that the body absorbs.
For example, to help stop zinc from being absorbed through the stomach, a doctor may prescribe H2 blockers or proton pump inhibitors to reduce stomach acid production.
In other cases, a doctor may use an IV drip to provide a drug called calcium disodium edetate. This medication helps rid the body of extra zinc by binding to it in the blood. The body then expels it through urine, rather than binding to other cells. This is known as chelation therapy (
If a person has accidentally swallowed items containing zinc, they may need surgery to remove the items (
Medications are also used to treat the physical side effects of zinc poisoning. For example, doctors may treat zinc poisoning from oral ingestion with antiemetics to stop vomiting and nausea (
If someone has zinc poisoning due to inhalation, doctors may administer medications to reduce flu-like symptoms and keep airways open.
Zinc poisoning is a potentially life threatening condition. It’s important to seek medical help immediately.
Although some foods contain zinc well above the UL of 40 mg daily, there are no reported cases of poisoning from naturally occurring zinc.
However, zinc overdose can occur from dietary supplements or accidental ingestion of too much zinc. It’s also possible to absorb high doses of zinc in other ways, such as through skin contact or by breathing in fumes.
Zinc toxicity can have both acute (immediate) and long-term (chronic) effects. The severity of your symptoms can depend on the dose and duration of intake.
Ingestion of high doses of zinc may cause acute gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain. In severe cases, gastrointestinal corrosion and bleeding can occur.
Long-term use may cause less immediate but serious side effects, such as low HDL (good) cholesterol, copper deficiency, and a suppressed immune system.
Overall, you should exceed the established UL only under the supervision of a medical professional.