The Dangers of Vitamin Overdose

Is it possible to get a vitamin overdose? We'll tell you in this article.

Reviewed and approved by el médico Diego Pereira.

Written by Josberth Johan Benitez Colmenares

Last update: 01 February, 2023

Millions of people around the world consume vitamin supplements to improve their health. Many of them don’t do so under medical supervision, and, in some cases, they may exceed the recommended daily dose. When this happens, they expose themselves to what is known as a vitamin overdose, which can lead to different health hazards.

Vitamin overdose is more common with those that are fat-soluble (A, D, E, and K), as these are stored in the body’s tissues. On the contrary, the water-soluble vitamins ( C, B1, B2, B3, B5, B6, B7, B9 and B12 ) are not stored in the tissues and are more easily excreted. Adverse effects can occur both with oral and topical intake. We’ll now go over some of the dangers of vitamin overdose.

5 dangers of vitamin overdose

The first thing you need to know is that the dangers of vitamin overdose are mainly related to the intake of supplements. It’s very difficult to exceed the daily limit of its intake naturally, even when foods are fortified. The same isn’t true when you opt for vitamin supplements, as it’s very easy to exceed the daily recommendations.

We have already established that the dangers of vitamin overdose are associated with those that are fat-soluble. In principle, an overdose of vitamin K isn’t possible. The only associated toxic episodes derive from the use of menadione (a water-soluble synthetic variant), also known as vitamin K3. It’s possible to develop allergies to any version of vitamin K, although it’s fair to say that they’re rare.

Having said that, the complications of vitamin overdose stem from the disproportionate intake of vitamin A, D, and E. The recommended doses for each of these are as follows:

• Vitamin A: 900 micrograms for adult men and 700 micrograms for adult women.
• Vitamin D: 15 to 20 micrograms starting at age 14.
• Vitamin E: an average of 15 milligrams per day for men and women over 14 years of age.

It’s important to emphasize that the recommended doses may vary according to the circumstances of the patient (pregnancy, lactation period, underlying diseases, and other factors). In any case, when these limits are exceeded, the following complications may appear.

1. Bleeding

We find vitamin E in foods such as breast milk, spinach, seeds, avocado, vegetable oil and almonds. Despite the recommended dosage, many supplements of the vitamin include doses ranging from 100 to 1,000 milligrams. As experts point out, excessive supplementation can cause vitamin E toxicity, which manifests itself in an increased risk of bleeding.

It is thought that high doses of vitamin E can alter the vitamin K precursors, which means a reduction in the circulation of the coagulation factors induced by them.

As a consequence, bleeding episodes may appear, which can be mild, moderate, or severe. Hemorrhagic strokes are known to be a complication resulting from excessive use.

2. Skin irritation

Researchers point to skin irritation as the main complication associated with excess vitamin A. It’s known as retinol burn or retinol irritation, and its main manifestations are erythema and scaling. In principle, it occurs after the topical administration of the vitamin present in cosmetic products.

The irritation is a consequence of hyperproliferation of the upper layer of the skin (epidermis) mediated by stimulation of the retinoic acid receptor. Associated complications include hypopigmentation, hyperpigmentation (in both cases transient), allergic contact dermatitis, and ectropion. It’s a very common complication, as vitamin A is widely used in dermatological products.

3. Teratogenicity

One of the biggest dangers associated with vitamin A overdose is teratogenicity. Scientists have found that in high doses this substance can lead to craniofacial abnormalities (such as cleft lip and palate), cardiac disorders (such as transposition of the great vessels), and thymic and central nervous system abnormalities (such as microcephaly and hydrocephalus). All this, of course, in developing fetuses.

In the case of its consumption by adults, it can cause dry mucous membranes, thinning of the skin, bone problems (osteoporosis and increased risk of fractures), headache, nausea, vomiting, and reversible kidney problems. It’s also known that it can compromise lipid metabolism, increasing the chances of developing hypertriglyceridemia.

4. Hypercalcemia

As experts remind us, hypercalcemia is the main complication associated with excess vitamin D. It refers to the excessive accumulation of calcium in the blood, which can cause nausea, weakness, dizziness, increased urination, bone pain, headache, muscle pain, memory loss, irritability, and other complications.

It can also increase the risk of developing calcium kidney stones, and, in the short term, it’s known to cause abdominal pain, confusion, listlessness, and dehydration. It isn’t possible to develop vitamin D toxicity as a consequence of sun exposure.

Since many try to compensate for this vitamin through supplements (especially during the winter) it’s a relatively common complication.

5. Liver damage

Finally, there’s evidence that severe liver complications from excess vitamin supplementation. The most severe problem is non-alcoholic liver cirrhosis, which can lead to portal hypertension. It’s more frequent due to hypervitaminosis A, although it can be triggered by excessive intake of different vitamin supplements.

It’s important to note that, like vitamins, minerals are associated with health complications when the recommended intake is exceeded.

For example, magnesium can cause diarrhea; iron constipation, nausea, vomiting, and reduced zinc absorption; phosphorus mild diarrhea, nausea, and vomiting; zinc nausea and vomiting, immunosuppression, and impaired copper uptake; and selenium brittle hair and nails, peripheral neuropathies, and gastrointestinal upset.

Supplements can be purchased without a prescription and there is wide acceptance among the general population to consume them. If you plan to start an intake regimen, consult a professional to adapt the dose to your gender, age, height, weight, health conditions, and diet. Indeed, many forget to add the dose they get from supplements to what they get from their regular diet.