Written through Jillian Kubala, MS, RD on January 20, 2020 — medically reviewed by approve Tinsley, PhD, Nutrition

Taking vitamins is part of the everyday routine that millions of people worldwide.

Though direction for safe dosing are noted on many supplement bottles, it’s typical practice to take an ext than what’s recommended.

Consumers room bombarded with wellness information telling them that acquisition high sheep of particular vitamins can benefit their wellness in numerous ways. However, acquisition too lot of some nutrients deserve to be dangerous.

This article reviews the safety of acquisition vitamins, and also the side effects and potential risks connected with spend high doses.

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Fat-soluble vs. Water-soluble vitamins
The 13 known vitamins are separated into 2 categories — fat-soluble and also water-soluble (1).

Water-soluble vitamins

Water-soluble vitamins are readily excreted indigenous the body and also not easily stored in tissues. There are an ext water-soluble vitamins than there are fat-soluble people (2).

Water-soluble vitamins incorporate vitamin C, add to eight B vitamins:

Vitamin B1 (thiamine)Vitamin B2 (riboflavin)Vitamin B3 (niacin)Vitamin B5 (pantothenic acid)Vitamin B6 (pyridoxine)Vitamin B7 (biotin)Vitamin B9 (folate)Vitamin B12 (cobalamin)

Because water-soluble vitamins no stored but rather excreted through urine, they’re less likely to reason issues even when take away in high doses.

However, taking megadoses of part water-soluble vitamins deserve to lead to potentially dangerous side effects.

For example, taking very high sheep of vitamin B6 have the right to lead to perhaps irreversible nerve damages over time, while taking large amounts that niacin — commonly in overabundance of 2 grams every day — can reason liver damages (3, 4).

Fat-soluble vitamins

Unlike water-soluble vitamins, fat-soluble vitamins carry out not dissolve in water and are conveniently stored in her body’s tissues (2).

There are 4 fat-soluble vitamins:

Vitamin AVitamin DVitamin EVitamin K

Given the fat-soluble vitamins have the right to accumulate in the body, these nutrients are much more likely to cause toxicity 보다 water-soluble vitamins.

While rare, taking too much vitamin A, D, or E deserve to lead to perhaps harmful side impacts (5).

Alternatively, acquisition high sheep of non-synthetic vitamin K seems to be fairly harmless, which is why an top intake level (UL) has not been set for this nutrient (6).

Upper intake levels are collection to indicate the maximum sheep of a nutrient it is unlikely to reason harm for nearly all people in a general populace (7, 8).


Water-soluble vitamin are conveniently excreted native the body, if fat-soluble vitamins have the right to be stored in tissues. Fat-soluble vitamins are more likely to reason toxicity, return water-soluble vitamins deserve to do so as well.

When consumed normally through foods, this nutrients are unlikely to cause harm, also when spend in large amounts.

Yet, once taken in concentrated doses in supplement form, it’s straightforward to take also much, and doing so have the right to lead to an adverse health outcomes.

Side impacts of overconsuming water-soluble vitamins

When take away in excess, some water-soluble vitamins can cause adverse effects, few of which can be dangerous.

However, likewise to vitamin K, certain water-soluble vitamins have actually no observable toxicity and also hence no collection UL.

These vitamins incorporate vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B5 (pantothenic acid), vitamin B7 (biotin), and also vitamin B12 (cobalamin) (9, 10, 11, 12, 13).

It’s crucial to note that while these vitamins have actually no observable toxicity, several of them may interact with medications and also interfere v blood trial and error results. Therefore, caution have to be taken through all nutritional supplements.

The following water-soluble vitamins have set ULs, as they can cause adverse side effects when bring away in high doses:

Note that these space side results that healthy world may experience once taking big doses of these vitamins. People with health problems can endure even much more serious reaction to acquisition too much of a vitamin.

For example, despite vitamin C is unlikely to reason toxicity in healthy people, it have the right to lead to organization damage and fatal love abnormalities in those with hemochromatosis, one iron warehouse disorder (19).

Side impacts related come overconsuming fat-soluble vitamins

Because fat-soluble vitamins deserve to accumulate in your body’s tissues, lock can cause much more harm once taken at high doses, especially over long periods.

Aside from vitamin K, which has actually a low potential because that toxicity, the continuing to be three fat-soluble vitamins have a set UL because of their potential to cause harm in ~ high doses.

Here room some side impacts related to the overconsumption that fat-soluble vitamins:

Although vitamin K has a short potential because that toxicity, the can communicate with particular medications, such as warfarin and also antibiotics (6).


Both water- and also fat-soluble vitamin can cause side impacts when taken in high doses, through some causing more severe symptoms than others.

Although it’s extremely rare to dice from a vitamin overdose, there have been report instances of death related to vitamin toxicity.

For example, hypervitaminosis A have the right to be resulted in by acquisition one large dose of end 200 mg the vitamin A, or chronic usage of an ext than 10 time the recommended everyday intake (23).

Vitamin A toxicity may result in serious complications, together as enhanced spinal fluid pressure, coma, and potentially deadly organ damage (23).

Additionally, acquisition megadoses that vitamin D — much more than 50,000 IU daily — over long periods can lead come high blood level of calcium (hypercalcemia), which deserve to lead to death (24).

Overdosing on various other vitamins can likewise cause potentially fatal next effects, such together liver damage.

A case report found that taking an extremely high sheep of over 5 grams that extended-release niacin can lead to metabolic acidosis, a buildup of acid in body fluids, as well as acute liver failure — both the which have the right to be fatal (25).

Keep in mind that these potentially deadly side impacts are connected with acquisition exceptionally high doses of vitamins. Even so, fist should always be taken once consuming any kind of dietary supplement.


In rare cases, taking extremely high sheep of specific vitamins may bring about fatal complications.

The best method to obtain the nutrient you need is by spend a well-rounded diet. However, many civilization need to supplement v vitamins for a variety of reasons.

Age, hereditary disorders, clinical conditions, and also diet are all components that have the right to increase the need for specific nutrients.

Fortunately, vitamins are generally safe to take as lengthy as lock are provided responsibly.

The adhering to chart outlines both the recommended day-to-day intake (RDI) and tolerable top intake level (UL) because that fat-soluble and also water-soluble vitamin (6, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22):

RDI because that adult menRDI for adult womenULVitamin AVitamin B1 (thiamine)Vitamin B2 (riboflavin)Vitamin B3 (niacin)Vitamin B5 (pantothenic acid)Vitamin B6 (pyridoxine)Vitamin B7 (biotin)Vitamin B9 (folate)Vitamin B12 (cobalamin)Vitamin CVitamin DVitamin EVitamin K
900 mcg retinol task equivalents (RAE)700 mcg RAE3,000 mcg RAE
1.2 mg1.1 mgNo UL established
1.3 mg 1.1 mgNo UL established
16 mg niacin equivalents (NE)14 mg NE35 mg
5 mg5 mgNo UL established
1.3 mg1.3 mg100 mg
30 mcg30 mcgNo UL established
400 mcg dietary folate equivalents (DFE)400 mcg (DFE)1,000 mcg
2.4 mcg2.4 mcgNo UL established
90 mg75 mg 2,000 mg
600 IU600 IU4,000 IU
15 mg15 mg1,000 mg
120 mcg90 mcgNo UL established

Due come potential toxicity, it’s not recommended to consume an ext than the tolerable upper intake levels set for the nutrients noted above.

Keep in mind the in details circumstances, your healthcare provider may recommend that you take much more than the UL for certain nutrients to correct a deficiency.

For example, vitamin D deficiencies are regularly treated v high-dose vitamin D injections or additional that deliver over 50,000 IU that vitamin D, i beg your pardon is much more than the UL (26).

Though most supplement bottles carry out recommendations about how much of a vitamin come take per day, needs have the right to vary from human to person.

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If you have questions regarding vitamin dosing, it’s ideal to top a medical professional.


Some vitamins have set ULs to avoid potential toxicity. It’s finest to above your healthcare provider if have questions regarding proper vitamin dosing.