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Doctors Warn The Public About Excessive Intake of Vitamins

Medically reviewed by Stephanie Nera, RPh, PharmD · Pharmacology

Written by Lorraine Bunag, R.N. · Updated Jan 13, 2022

Doctors Warn The Public About Excessive Intake of Vitamins

As of this writing, there are still shortages in the supply of over-the-counter medicines, like paracetamol and carbocisteine. This makes people worry: what if they get sick? To compensate, many resort to supplements, like vitamin C and zinc. But can you overdose on vitamins? Doctors say, you can. Which vitamins are toxic if taken in excess?

Let’s find out in this article.

The Difference Between Medications and Supplements

Overdose in medications is quite easy to prevent – do not take anything more than what your doctor has prescribed. For instance, taking too much of an antihypertensive drug could result in symptoms like a sudden drop in blood pressure.

Vitamins and minerals are quite tricky. Most people get them without a doctor’s prescription and many could buy them in retail. As we know, when we buy vitamins and minerals few pieces at a time (“tingi”), the little pamphlet that talks about the supplement is usually not included in the purchase. This reduces the person’s chance to learn details about the supplement, such as its recommended dosage and interactions.

Can You Overdose on Vitamins and Minerals?

Before we discuss which vitamins are toxic when taken in excess, let’s first define vitamin overdose.

An overdose happens when a person takes more than the recommended daily dose for an extended time. So, yes, you can overdose on vitamins and minerals.

Which Vitamins Are Toxic if Taken in Excess?

Here are common vitamins that Filipinos take that could be toxic when taken excessively.

Vitamin C

The recommended daily amount of vitamin C (ascorbic acid, sodium ascorbate) is 60 to 90 mg. However, we have an upper limit of 2,000 mg daily. Too much vitamin C could result in symptoms like:


An overdose in B- vitamins is also possible. We have a total of 8 B- vitamins and some of them are “generally nontoxic.” Additionally, some form of vitamin B has no established upper limit.

  • Vitamin B3 or Niacin. The recommended daily allowance (RDA) for B3 is 9 mg for children aged 1 to 4 and 20 mg for adults. If you take more than 50 mg daily, you may experience skin flushing. Additionally, people with pre-existing liver conditions are at a higher risk of liver toxicity if they receive therapeutic doses of 1,500 to 1,600 mg daily.
  • Vitamin B5 or pantothenic acid. As of now, it is not known to be toxic to humans. Additionally, there is no established upper limit dose, but the recommended intake is 5 mg daily. Some people experience diarrhea with doses of 10 to 20 g per day.
  • Vitamin B6 or pyridoxine. The RDA for adults 19 to 50 years old is 1.3 mg. It could potentially lead to neurotoxicity when taken at doses of 300 to 500 mg per day over extended time.
  • Vitamin B12 or folic acid. For adult men and women, the RDA is 400 micrograms. If you are pregnant, however, the RDA may increase to 600 micrograms. A high dose of folic acid may result in loss of appetite, nausea, stomach problems, sleep problems, and skin reactions.

Vitamin E

Best known for its antioxidant properties, the recommended intake of Vitamin E for adults is 15 to 20 mg or 22 to 30 IU. Although some people take large amounts for months and years without experiencing any consequence, there are still potential toxic effects associated with supplements, like:

  • Nausea and vomiting
  • Diarrhea
  • Blurred vision
  • Increased risk of bleeding
  • Headache
  • Fatigue

Vitamin D

Can you overdose on vitamins like vitamin D? It turns out that you can.

A vitamin we normally take from being exposed to the sun, vitamin D helps in the promotion of bone health. The recommended intake is 10 to 25 micrograms or 400 to 1,000 IU. Large amounts of vitamin D supplements may lead to soft-tissue calcification or increased calcium in the blood.

Vitamin A

Also called retinol, this vitamin’s recommended intake is 900 to 1,500 micrograms per day. Intake of more than 200,000 micrograms or 660,000 IU can lead to acute toxicity, which manifests into symptoms such as blurry vision, nausea and vomiting, drowsiness, and vertigo.

Long-term ingestion of more than 10x the recommended daily allowance, on the other hand, can result in chronic toxicity. Some of the symptoms of chronic toxicity are: visual problems, alopecia, and bone and muscle pain.

Finally, pregnant women should not take vitamin A unless recommended by the doctor. Intake of vitamin A in the first trimester can lead to abortion or fetal malformations.

can you overdose on vitamins


People with anemia often take iron supplements to remedy their symptoms. For adults aged 19 to 50 years old, the RDA for males is 8 mg. Women are advised to take 18 mg of iron daily. An overdose to iron may lead to:

  • Headache
  • Dizziness
  • Nausea
  • Diarrhea
  • Tarry or black-colored stool
  • Fluid buildup in the lungs
  • Fever

While iron is essential, too much can lead to iron overload. This excess iron gets deposited into other organs of the body, including the liver, heart, and pancreas. These organs are damaged by too much iron and can lead to conditions such as liver cirrhosis, arrhythmias, and decreased insulin.


For healthy bones, many people take calcium supplements. But, can you overdose on vitamins and minerals like calcium?

The RDA of calcium for adults aged 19 to 50 years old is 1,000 mg with an upper limit of 2,500 mg. Too much calcium can cause:

Additionally, high doses of calcium could also potentially interfere with the absorption of zinc and iron, however, we still need more studies to fully establish the effect.


We often hear zinc in supplements that aim to boost the immune system. For adults, the upper daily limit of zinc is 40 mg. If you take too much zinc, you might develop:

  • Loss of appetite
  • Nausea and vomiting
  • Stomach cramps
  • Diarrhea

Additionally, if someone is taking too much zinc for an extended period, it may compromise their immunity. Finally, they could also potentially develop problems with their copper and good cholesterol levels.

Key Takeaways

Remember that the RDA talks about the recommended intake from both diet and supplements. In other words, you do not have to complete the RDA from supplements alone. A balanced diet is always important.

Can you overdose on vitamins and minerals? Yes, so it is best to take them with the doctor’s advice, especially if you have an underlying condition.

Learn more about Healthy Eating here


Hello Health Group does not provide medical advice, diagnosis or treatment.

Medically reviewed by

Stephanie Nera, RPh, PharmD


Written by Lorraine Bunag, R.N. · Updated Jan 13, 2022

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