If you are one of the many adults in the United States who takes one or more supplements daily, you may wonder if it's possible to take too many vitamins. How many vitamins you can take in a day depends on the supplement and how much of the vitamin you already get in your diet. Combining too many supplements or taking more than the recommended dosage can increase the risk of overdose.
Keep in mind that the Food and Drug Administration does not have to test supplements for efficacy or safety before they hit the market. Always consult a healthcare provider before taking a new supplement. They can tell you how much of each nutrient you need. Learn more about how to take supplements safely.
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Supplements come in many forms, such as capsules, gummies, powders, and tablets. Some manufacturers add nutrients to drinks and energy drinks. Always check with a healthcare provider before starting a new supplement. The Food and Drug Administration does not check whether supplements are effective or safe before they hit the market.
You might need supplements if you cannot meet your daily intake goals of certain minerals and vitamins through your diet alone. Still, many people get enough minerals and vitamins from a nutrient-rich diet.
"For the average healthy person, you probably don't need a multivitamin, multimineral supplement,"Beth Kitchin, PhD, RDN, an assistant professor in the department of nutrition sciences at the University of Alabama at Birmingham, toldHealth. "You certainly don't need a lot of additional supplements on top of that."
There's a lack of evidence showing whether supplements help prevent or treat health conditions. For example, a study published in 2018found that regular supplement use has no net effect on heart health or the risk of early death. The research team's findings were consistent for multivitamins, calcium, and vitamins C and D, all of which people have touted for heart health.
"We found a surprising neutrality of effects,"David Jenkins, MD, PhD, lead author of the 2018 study, toldHealth. "In other words, it didn't seem to do anything."
The 2018 study only looked at heart problems and early death. Some supplements might benefit your bone, eye, and skin health. For example, calcium and vitamin D help prevent bone loss, especially in people with a high risk of osteoporosis. Pregnant people benefit from taking folic acid, which helps minimize the risk of birth defects.
What To Know About Supplements
Vitamins With Potential for Overdose
You might develop adverse effects—as well as spend too much money—if you take too many supplements. Some minerals and vitamins can build up in your blood over time and raise your risk of an overdose. An overdose might happen by accident. Some manufacturers fortify foods and drinks with nutrients, so you may not realize how much you consume.
"You really can't get toxic doses of nutrients through food, but you can absolutely get toxic doses through supplements," said Kitchin. "We've learned a very important lesson, in that when we isolate these nutrients out of food and put them in super-high doses, we may have some unintended consequences."
Any one nutrient can be toxic in excess amounts, though B vitamins and vitamin K do not usually cause toxicity. Some of the most severe risks of an overdose come from calcium and iron supplements. For example, too much calcium in your blood or urine might increase your risk of heart disease and prostate cancer. An iron overdose might cause coma or low blood pressure and damage your intestines and liver.
Other vitamins with a potential for overdose include:
- Vitamin A:Taking too much vitamin A might lead to coma and death in severe cases and harm pregnant and breastfeeding people. Excess vitamin A may also harm the fetus during pregnancy and cause abnormal development of the eyes, heart, lungs, and skull.
- Vitamin D:Vitamin D boosts how much calcium your gut absorbs. As a result, you might have too much calcium in your blood or urine.
- Vitamin E:Excess vitamin E might increase the risk of hemorrhagic stroke, or sudden bleeding in the brain.
The Food and Nutrition Board (FNB) at the National Academies of Sciences, Engineering, and Medicine (NASEM) has established tolerable upper intake levels (ULs) for many minerals and vitamins. The FNB has not established ULs for vitamin K since the toxicity risk is low.
ULs are how much of each nutrient you can take without harming your health. Your UL for any one nutrient might depend on your age.
Here are the ULs for some of the most common supplements for males and females aged 0 months to 71 years and older, regardless of whether you are pregnant or breastfeeding:
| Tolerable Upper Intake Levels (ULs) | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| 0–6 months | 7–12 months | 1–3 years | 4–8 years | 9–13 years | 14–18 years | 19–50 years | 51–70 years | 71 years and older | |
| Calcium | 1,000mg | 1,500mg | 2,500mg | 2,500mg | 3,000mg | 3,000mg | 2,500mg | 2,000mg | 2,000mg |
| Iron | 40mg | 40mg | 40mg | 40mg | 40mg | 45mg | 45mg | 45mg | 45mg |
| Vitamin A | 600mcg | 600mcg | 600mcg | 900mcg | 1,700mcg | 2,800mcg | 3,000mcg | 3,000mcg | 3,000mcg |
| Vitamin D | 25mcg | 38mcg | 63mcg | 75mcg | 100mcg | 100mcg | 100mcg | 100mcg | 100mcg |
| Vitamin E | N/A | N/A | 200mg | 300mg | 600mg | 800mg | 1,000mg | 1,000mg | 1,000mg |
Symptoms of Overdose
You might develop overdose symptoms if you take too much of any one nutrient. It's essential that you do not force yourself or another person to vomit unless a healthcare provider instructs you to do so.
Multivitamin overdose generally causes symptoms that might include:
- Bone, joint, or muscle pain
- Cloudy urine
- Diarrhea
- Dry, cracked lips or skin
- Headache
- Irregular or rapid heartbeat
- Mood changes (e.g., irritability)
- Nausea and vomiting
- Seizures
- Stomach pain
Some minerals and vitamins might cause specific symptoms. For example, an iron overdose might cause bloody, dark diarrhea and weakness, while a vitamin A overdose can lead to blurry vision and dizziness. Excess calcium in your blood, which may result from taking too much calcium or vitamin D, may cause a lack of appetite, kidney stones, and muscle weakness.
Always consult a healthcare provider or pharmacist before taking a new supplement. They can tell you whether a supplement might help prevent or treat a health condition or pose safety risks. Make sure you ask what dosage is best for you and when it's best to take the supplement. Dosage and timing recommendations might vary between people.
Tell a healthcare provider if you are:
- About to have surgery
- Breastfeeding
- Pregnant
Keep in mind the supplements might interact with any medications you are taking. For example, vitamin A may decrease the function of warfarin, a blood thinner. Vitamin E might reduce the efficacy of some chemotherapies.
Combining multiple supplements or taking more than the recommended dose might raise the risk that they can cause harm, said Kitchin. To lower your risk of an overdose, try looking for a multivitamin with no more than 100% of the daily value for any one nutrient to avoid an overdose, said Kitchin.
In any case, it's essential to focus on getting your nutrients from food first rather than supplements, said Dr. Jenkins: "Pills are not a substitute for a good diet: plant-based, fruit, veggies, whole grains, nuts, and seeds. These are packed with what you need."
Safety Tips for Children
Approximately 35,000 children are treated in the emergency room every year after getting into medicines at home or receiving the wrong dose from an adult. Dosage instructions for children are much different than those for adults—a dose that is safe to take for an adult can be toxic to a child. To prevent a child from accidentally ingesting a toxic dose, it is important to properly store any vitamins you have at home. The Centers for Disease Control and Prevention (CDC) recommends:
- Storing vitamins and medications in a safe spot, out of sight and reach of children.
- Always making sure the safety lock on the bottle is engaged.
- Putting vitamins and medications away promptly so children don't have an opportunity to access them.
- Reminding guests to be careful of their vitamins or medications.
- Finding a safe storage place when traveling.
When To See a Healthcare Provider
Seek medical attention right away if you or someone you love develops overdose symptoms or if you suspect a child has consumed too many vitamins. Never force yourself or someone else to vomit unless a healthcare provider directs you.
Call the Poison Help hotline at 1-800-222-1222, a free service available to anyone in the United States that will connect you to your local poison control center. You do not need an emergency to call the Poison Help hotline. Your local poison control center can provide information about supplements and their safety risks.
You might need to provide the following information about you or the person who has overdosed:
- Age
- Health conditions
- How much of the supplement was consumed
- The time the supplement was taken
- The type and dosage of the supplement
- Weight
It might be helpful to take the supplement container with you to the emergency room. A healthcare provider can report any adverse reactions to a supplement to the Food and Drug Administration.
Supplements That Should Not Be Mixed
Research has found that taking a lot of supplements does not have significant benefits and, in some situations, could be harmful. Avoid combining too many supplements or taking more than what the label or a healthcare provider recommends.
People who eat various nutrient-rich foods live longer, healthier lives, so enjoy plenty of fruits, vegetables, and whole grains. Talk with a healthcare provider if you are unsure if you would benefit from supplements. They might advise taking certain supplements in moderation if you are lacking nutrients in your diet.
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14 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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