Key Takeaways
- You can overdose on vitamins, leading to serious health risks.
- Fat-soluble vitamins (A, D, E, and K) build up in the body and have a higher toxicity risk.
- Stick with recommended doses and check with a healthcare provider if you take multiple vitamins or have health concerns.
Getting the right amount of vitamins is necessary for your body to function properly, but taking excess vitamins can be toxic (hypervitaminosis). Vitamin overdose symptoms can include a skin rash, upset stomach, seizure, or stroke.
Can Excess Vitamins Harm Your Health?
Taking excess vitamins can harm your health, especially if you take high doses or take them for an extended period.
Serious risks associated with high doses of vitamins include the following:
- Increased mortality risk: Consistently high doses of vitamin E supplements (≥400 international units (UI)/day) are associated with an increased risk of death.
- Cancer risk: Studies have shown that high doses of vitamins A, B6, and B12 may increase lung cancer risk. Vitamin E supplementation in large amounts may cause cancer to recur after radiation treatment.
- Congenital disabilities: Taking high doses of vitamin A during pregnancy can cause abnormalities in the fetus, including heart and brain damage.
- Fracture risk: Taking too much vitamin A or vitamin D can lower bone mineral density and increase the likelihood of bone fractures.
What To Do If You’ve Taken Too Much
If you think you or a loved one has taken too many vitamins:
- Call Poison Help: 1-800-222-1222
- Call 911 if symptoms are severe (trouble breathing, seizures)
- Keep vitamins stored safely away from children and pets, stored up high or in a locked box.
Fat-Soluble vs. Water-Soluble Vitamins
Vitamins are classified as either dissolvable in fat (fat-soluble) or dissolvable in water (water-soluble):
Risks of Excess Fat-Soluble Vitamin Intake
Fat-soluble vitamins stay in the body longer and are more likely to build up and cause toxicity if taken in excess.
Symptoms of too much vitamin A include:
- Skin peeling
- Liver problems
- Vision loss
- Increased pressure in the skull (intracranial hypertension)
Symptoms of too much vitamin D include:
- Excessive urination
- Seizures
- Coma
- Bone fractures
Symptoms of too much vitamin E include:
Risks of Excess Water-Soluble Vitamin Intake
Water-soluble vitamins are generally safer than fat-soluble vitamins because they don’t accumulate in the body. If you take too much of these vitamins, your body usually removes them through your urine.
Symptoms of a water-soluble vitamin overdose are often nonspecific, meaning they are vague and may not be immediately traced to the vitamin. These symptoms can include:
- Nausea
- Vomiting
- Diarrhea
- Skin rash
Who’s at Risk of Toxicity
Though anyone who takes vitamin supplements may experience vitamin toxicity, some populations are at greater risk:
- Babies: Breastfed babies may develop excessive vitamin levels if their mothers take vitamin supplements. Infant formulas for premature babies often contain high amounts of vitamin D, which may cause toxicity if they are consumed for an extended period.
- Children: Many vitamins look like candy or gummies, which makes them especially appealing to children.
- Pregnant people: High levels of vitamin A in the first trimester of pregnancy can cause heart or brain abnormalities in the fetus or miscarriage.
- Older adults: Older adults may break down and eliminate substances differently than younger people and may have higher or lower levels of vitamins after a standard dose. For example, older adults may be more likely to experience cognitive problems if they take too much vitamin D.
- People taking multiple vitamins: You are more likely to take too much of a vitamin if you take a daily multivitamin or another vitamin combination plus a single-ingredient vitamin.
How Much of Each Vitamin Do I Need?
Healthy, nonpregnant people who eat a balanced diet typically do not need to supplement with vitamins. Research shows that most people who take vitamin supplements already get the recommended amounts of vitamins through food.
When determining how much of each vitamin you need, consider the amounts you consume in your diet plus any supplements you take (including multivitamins). Food sources include:
- Vitamin A: Dietary sources include dairy, eggs, and fish.
- Vitamin B3: Vitamin B3, also known as niacin, is found in meats like chicken, beef, and fish.
- Vitamin C: Fruits and vegetables are rich in vitamin C.
- Vitamin D: The body makes vitamin D through exposure to sunlight. Some fish contain vitamin D, and many other foods are fortified with it.
- Vitamin E: Dietary sources include nuts, seeds, and oils.
The Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine provides the following Recommended Dietary Allowances (RDAs) and Upper Limits (ULs) of vitamins for adults:
| RDAs and ULs of Vitamins for Adults | |||
|---|---|---|---|
| Vitamin | RDA | UL | Main Side Effects |
| Vitamin A (retinol) | Males: 900 micrograms per day (μg/d) Females: 700 μg/d Pregnancy: 770 μg/d Lactation (breastfeeding): 1300 μg/d |
3,000 μg/d | Skin peeling, liver problems, vision loss, pressure in the brain (intracranial hypertension) |
| Vitamin B1 (thiamin) | Males: 1.2 milligrams per day (mg/d) Females: 1.1 mg/d Pregnancy and lactation: 1.4 mg/d |
Unknown | Weakness, irritability, trouble sleeping |
| Vitamin B2 (riboflavin) | Males: 1.3 mg/d Females: 1.1 mg/d Pregnancy: 1.4 mg/d Lactation: 1.6 mg/d |
Unknown | Stomach pain, diarrhea |
| Vitamin B3 (niacin) | Males: 16 mg/d Females: 14 mg/d Pregnancy: 18 mg/d Lactation: 17 mg/d |
35 mg/d | Liver damage, skin flushing or burning, hypotension (low blood pressure) |
| Vitamin B5 (pantothenic acid) | Pregnancy: 5 mg/d, 6 mg/d Lactation: 7 mg/d |
Unknown | Diarrhea, upset stomach |
| Vitamin B6 (pyridoxine) | Males: 1.3-1.7 mg/d Females: 1.3-1.5 mg/d Pregnancy: 1.9 mg/d Lactation: 2 mg/d |
100 mg/d | Nerve pain (peripheral neuropathy) |
| Vitamin B7 (biotin) | Adults: 30 μg/d Lactation: 35 μg/d |
Unknown | Can affect thyroid function tests |
| Vitamin B12 (cobalamin) | Adults: 2.4 μg/d Pregnancy: 2.6 μg/d Lactation: 2.8 μg/d |
Unknown | Nausea, vomiting, diarrhea, hypertension (high blood pressure), slow heart rate, anaphylaxis (severe allergic reaction) |
| Vitamin C (ascorbic acid) | Males: 90 mg/d Females: 75 mg/d Pregnancy: 85 mg/d Lactation: 120 mg/d |
2,000 mg/d | Diarrhea, kidney stones |
| Vitamin D (colecalciferol) | Adults: 15-20 μg/d Pregnancy and lactation: 15 μg/d |
100 μg/d | Thirst, excessive urination, seizures; falls and bone fractures in older adults |
| Vitamin E (alpha-tocopherol) | Adults: 15 mg/d Lactation: 19 mg/d |
1,000 mg/d | Excessive bleeding, stroke |
| Vitamin K | Males: 120 μg/d Females: 90 μg/d |
Unknown | Anaphylaxis, cardiac or respiratory arrest with injectable forms |
| Folic acid | Adults: 400 μg/d Pregnancy: 600 μg/d Lactation: 500 μg/d |
1,000 μg/d | Stomach cramps, nausea, diarrhea |
When to Speak With Your Healthcare Provider
Discuss your goals with your healthcare provider if you are considering taking a vitamin supplement. Some things to consider before starting a supplement include:
- Current vitamin levels: A blood test can help clarify whether or not you need to supplement.
- Diet: You only need small amounts of vitamins. Most healthy people get these by eating a variety of plant- and animal-based foods.
- Health conditions: If you are pregnant, breastfeeding, on a restrictive diet, or have other medical conditions, discuss vitamin use with a healthcare provider to be sure you are taking the correct dose and that it’s safe for you.
In the United States, the Food and Drug Administration (FDA) does not regulate dietary supplements the way it regulates prescription medications. As a result, some supplement products may not contain the ingredients listed on the label. When choosing a supplement, look for products independently tested or certified by organizations such as the National Sanitation Foundation (NSF), U.S. Pharmacopeia (USP), or ConsumerLab.com. For personalized guidance, consult your healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.
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