Vitamin D3 (cholecalciferol) is an over-the-counter dietary supplement that's taken by mouth to raise vitamin D levels. It's for adults and children who aren't getting enough vitamin D through food or sunlight, or for people who've certain conditions that cause vitamin D deficiency, like liver or kidney problems. Vitamin D3 (cholecalciferol) is usually taken daily, but it's sometimes taken weekly, depending on the dose. Vitamin D3 (cholecalciferol) isn't known to cause any side effects if you're taking the recommended dose.
Low vitamin D levels
Vitamin D3 (cholecalciferol) is a dietary supplement that boosts your body's vitamin D levels when it's low.
Vitamin D is a hormone that your body naturally makes. You can also get it through the foods you eat. Vitamin D is very important to help your body work properly. For example, you need vitamin D to absorb calcium, which is important to keep your bones strong. In addition, you also need vitamin D for healthy muscles, nerves, and immune systems.
Source: DailyMed
Side effects that you should report to your care team as soon as possible:
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Raises vitamin D levels better than vitamin D2 (ergocalciferol)
Available over the counter
Comes in many different forms (e.g., liquid, gummies, tablets, capsules)
Available as a once-weekly, high-dose capsule (taken only if instructed by your provider)
Some forms of vitamin D3 (cholecalciferol) are animal-based, which can be a problem for vegetarians, vegans, and people of certain faiths.
Too much vitamin D can cause side effects that can last for months after stopping the supplement.
Can be easy to forget to take, since you can't feel vitamin D3 (cholecalciferol) working
Only take high-dose (50,000 IU) vitamin D3 (cholecalciferol) if your provider tells you to do so. Most people don't need to take this much. Don't take more than instructed by your provider to avoid side effects, and be sure to get any ordered blood tests done on time.
Contact your provider if you notice an unexplainable loss of appetite, nausea, constipation, weight loss, weakness, general aches, or stiffness. These might be signs that you're taking too much vitamin D.
If you're using the liquid version of vitamin D3 (cholecalciferol) , use the medication dropper that comes with the package to measure each dose. If a dropper didn't come with your package, ask your pharmacy to provide you with one. Don't use household teaspoons to measure out your dose of vitamin D3 (cholecalciferol) , since these can cause you to take the wrong dose.
Make sure your providers have a list of all your medications and supplements you take on a regular basis, including those purchased over the counter. You might already be taking a product that includes vitamin D, and taking too much can lead to side effects.
Vitamin D3 (cholecalciferol) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Vitamin D3 (cholecalciferol) shouldn't be used if you have high levels of calcium or vitamin D in your blood. If you take more vitamin D3 (cholecalciferol) than the recommended or prescribed dose, it can cause calcium to build up in your blood. This can be dangerous for your kidneys. If you're taking vitamin D3 (cholecalciferol) to treat low vitamin D levels or other conditions diagnosed by your provider, be sure to get all ordered blood tests done on time. That way, your provider can make sure your vitamin D levels aren't too high and you're taking the correct dose. If you notice unexplained nausea that doesn't go away, a loss of appetite, weight loss, constipation, muscle pain, muscle stiffness, or a change in how much or how often you urinate, talk to your provider. These could be early signs that you're taking too much vitamin D and your calcium blood level is too high.
Vitamin D3 (cholecalciferol) is taken by mouth. Your dose will depend on your individual needs. Ask your healthcare provider or pharmacist about what dose and how often you should take vitamin D3 (cholecalciferol) .
Vitamin D3 (cholecalciferol) comes in many different strengths. The dose of vitamin D3 (cholecalciferol) is measured in both micrograms (mcg) and international units (IU): 1 mcg vitamin D is equal to 40 IU.
The highest strength of vitamin D3 (cholecalciferol) is 1,250 mcg (which is 50,000 IU) and is typically reserved to treat very low vitamin D levels and certain related conditions.
High blood calcium levels
High blood vitamin D levels
Malabsorption syndrome (when your body can't absorb nutrients)
Hypoparathyroidism (low parathyroid hormone levels)
Familial hypophosphatemia (genetic condition causing low phosphate levels)
Vitamin D-resistant rickets (weakening of the bones caused by low vitamin D)
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American Association of Clinical Endocrinologists. (2019). Vitamin D deficiency.
Centers for Disease Control and Prevention. (2022). Vitamin D.
Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. (2011). 3: Overview of vitamin D. Dietary Reference Intakes for Calcium and Vitamin D.
Marcinowska-Suchowierska, E., et al. (2018). Vitamin D toxicity-A clinical perspective. Frontiers in Endocrinology.
National Institutes of Health, Office of Dietary Supplements. (2022). Vitamin D: Fact sheet for consumers.
National Institutes of Health, Office of Dietary Supplements. (2023). Vitamin D: Fact sheet for health professionals.
People for the Ethical Treatment of Animals. (2015). 5 ways to increase your vitamin D intake.
Pharmin USA, LLC. (2017). Decalcitrol- cholecalciferol tablet, coated [package insert]. DailyMed.
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