Vitamins are nutrients that can be obtained through the diet or as dietary supplements. Getting the right amount of vitamins is necessary for your body to function properly.
You may not know that taking excess vitamins can cause a slew of health problems, including toxicity (hypervitaminosis). Vitamin overdose symptoms can include a skin rash, upset stomach, seizure, or stroke.
Can Excess Vitamins Harm Your Health?
Yes, taking excess vitamins can harm your health.
Vitamin supplements are often considered a harmless way to improve health. However, be mindful that there are risks associated with vitamins. This is especially important 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 developing baby, 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 Overdose on Vitamins
If you think you or a loved one has taken too many vitamins, contact the Poison Help line at 1-800-222-1222. This national service will connect you to your local poison center for guidance on the next steps.
If you or a loved one experiences a seizure or difficulty breathing, call 911 right away.
Fat-Soluble vs. Water-Soluble Vitamins
Vitamins are classified as either dissolvable in fat (fat-soluble) or dissolvable in water (water-soluble).
Fat-soluble vitamins include vitamins A, D, E, and K.
Water-soluble vitamins include all eight B vitamins and vitamin C.
Risks of Excess Fat-Soluble Vitamin Intake
These vitamins stay in the body longer and are more likely to build up in the body. This means that fat-soluble vitamins are more likely to cause toxicity.
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. These include the following groups:
- 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 length of time.
- Children: Children are at high risk of accidentally taking too much medicine. Many vitamins are marketed to look like candy or gummies, which makes them especially appealing to children.
- Pregnant people: Though vitamin deficiency during pregnancy can harm a developing baby, too much can also be dangerous. In fact, pregnant people in developed countries are more likely to have too much vitamin A than too little. High levels of vitamin A in the first trimester of pregnancy can cause heart or brain abnormalities in the baby or miscarriage.
- Older adults: Older adults may break down and eliminate medicines differently than younger people do. This means they may have higher or lower levels of vitamins in the body after a standard dose than a younger person would. 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.
Safe Storage Tips
To prevent vitamin toxicity, store vitamins safely, just like you do for other medications. Store them up high or in a locked box, out of reach of children and pets. Be mindful that some vitamins may look like candy to children, making them especially dangerous.
How Much of Each Vitamin Do I Need?
It’s important to remember that healthy, nonpregnant people who eat a balanced diet typically do not need to supplement with vitamins. In fact, 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). Here’s what to aim for when it comes to a few heavy hitters:
- Vitamin A: Daily needs vary from 700 to 1300 micrograms (µg) per day, depending on gender and whether you’re pregnant or breastfeeding. Vitamin A is crucial for vision, bone growth, and a healthy immune system. Dietary sources include dairy, eggs, and fish.
- Vitamin B3: The recommended intake is 14 to 18 milligrams (mg) daily, depending on gender and pregnancy status. Vitamin B3, also known as niacin, is found in meats like chicken, beef, and fish. The body needs it to make energy.
- Vitamin C: Males should aim for 90 mg daily, while females need 75 to 120 mg daily, depending on pregnancy and lactation status. Vitamin C is an antioxidant that helps the body build collagen and break down protein. Humans don’t make vitamin C, so they must consume it through their diets or supplements. Fruits and vegetables are rich in vitamin C.
- Vitamin D: Most adults require 15 µg of vitamin D daily. The body makes vitamin D through exposure to sunlight. It is crucial for bone health. Some fish contain vitamin D, and many other foods are fortified with it.
- Vitamin E: Aim for 15 mg a day or 19 mg if you’re breastfeeding. Vitamin E is an antioxidant that boosts the immune system and protects against damage caused by free radicals. 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 (breastfeeding): 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 (breastfeeding): 1.6 mg/d | Unknown | Stomach pain, diarrhea |
| Vitamin B3 (niacin) | Males: 16 mg/d Females: 14 mg/d Pregnancy: 18 mg/d Lactation (breastfeeding): 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 (breastfeeding): 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 (breastfeeding): 2 mg/d | 100 mg/d | Nerve pain (peripheral neuropathy) |
| Vitamin B7 (biotin) | Adults: 30 μg/d Lactation (breastfeeding): 35 μg/d | Unknown | Can affect thyroid function tests |
| Vitamin B12 (cobalamin) | Adults: 2.4 μg/d Pregnancy: 2.6 μg/d Lactation (breastfeeding): 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 (breastfeeding): 120 mg/d | 2,000 mg/d | Diarrhea, kidney stones |
| Vitamin D (colecalciferol) | Adults: 15-20 μg/d Pregnancy and lactation (breastfeeding): 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 (breastfeeding): 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 (breastfeeding): 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: If you or your healthcare provider is concerned about a vitamin deficiency, a simple blood test can help clarify whether or not you need to supplement.
- Diet: Remember that you only need small amounts of vitamins (mere milligrams or micrograms). 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.
Summary
Vitamins are crucial to the human body, but high doses can be harmful. Most people who eat a healthy diet consume enough vitamins to meet their body’s needs. However, some people require vitamin supplements to achieve the recommended levels of vitamins.
Symptoms of vitamin overdose can range from mild (stomach upset or a skin rash) to severe (liver damage, seizures, or stroke). Fat-soluble vitamins A, D, E, and K are more likely to accumulate in the body and cause side effects.
As you aim for daily vitamin goals, consider the amounts of each vitamin you get from your diet, plus any vitamin supplements you take. Discuss vitamin supplements with your healthcare provider before taking them for optimal safety.
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