Nov 23, 2022



Vitamin D2 vs. D3: What's the Difference?

Vitamin D

Vitamin D is a key component of our health. However, research shows that over 35% of adults in the United States and 50% of the world's population suffer from a vitamin D deficiency. 

People with insufficient vitamin D increase their risk of their bones becoming fragile, making them more prone to falls and fractures. Some early studies suggest a vitamin D deficiency can contribute to diabetes, heart disease, poor immune function, and cognitive decline. 

While vitamin D can be found in foods and sun exposure, sometimes a person may need to take a vitamin D supplement. There are two forms of vitamin D available, vitamin D2 and vitamin D3. 

We put together this guide to compare the two and help you decide which might be the better option for increasing your vitamin D levels.  

Find the lowest price for Vitamin D here and get free instant savings coupons for your local pharmacy here.  No insurance or sign up is required.

What is vitamin D? 

Vitamin D is a nutrient found in certain foods and a hormone our bodies make that helps absorb and retain calcium and phosphorus, both essential to bone and muscle health. 

More recent studies have shown that vitamin D also supports the immune system

Sources of vitamin D

While there aren't many foods that naturally contain vitamin D, you can find it in:

  • oily fish (salmon, sardines, trout, herring, and mackerel)

  • cod liver oil

  • shrimp

  • canned tuna

  • beef liver

  • red meat

  • egg yolk

  • wild mushrooms or mushrooms treated with ultraviolet light

A majority of the vitamin D in our diets comes from fortified foods, like cow's milk, soy milk, cereals, oatmeal, yogurt, and orange juice. 

The body also creates vitamin D as a result of sun exposure through our skin. The season, time of day, latitude, altitude, air pollution, skin pigmentation, sunscreen use*, and aging all play a significant role in how much vitamin D the body absorbs from the sun. 

*The American Academy of Dermatology recommends using broad-spectrum sunscreen with an SPF 30 or higher before going outside to protect against skin cancer. 

What is vitamin D2?

Also known as ergocalciferol, vitamin D2 comes from plants, specifically mushrooms, and yeast. It's also what's commonly used in fortified foods. 

What is vitamin D3?

Vitamin D3, or cholecalciferol, is naturally produced by animals, including humans. It can be found naturally in certain foods (see above) as well as from sunlight. 

Vitamin D2 vs. Vitamin D3

When comparing the two, vitamin D2 and D3 have similarities and differences. 

While both perform the same role in the body, vitamin D2 and vitamin D3 do have some differences. 


The source from which they are formed is one distinction. D2 is derived from plants while D3 comes from animals. 

Supplement forms available 

Vitamin D2 and vitamin D3 are available in oral tablets, capsules, and sublingual solutions.

Dosage strengths

Both supplements are available over-the-counter in 400 IU, 1,000 IU, 2,000 IU, 5,000 IU, and 10,000 IU. 

A prescription vitamin D2 is available with a strength of 50,000 IU. 


Many studies have shown that vitamin D3 is more effective at increasing vitamin D levels. However, there is research that debates those findings. 

Do I need a prescription for vitamin D2 or vitamin D3?

Many people with a vitamin D deficiency don't require vitamin D prescription medication and do well with an OTC supplement. 

Doctors usually recommend a prescription if you suffer from chronic kidney or liver disease and are vitamin D deficient. Drisdol (ergocalciferol) is only as available as vitamin D2. 

Can I take too much vitamin D2 or vitamin D3?

Vitamin D (both D2 and D3) is considered safe when taking the recommended amount. Taking too much vitamin D in the supplement form can be harmful and cause:

  • Nausea

  • Vomiting

  • Constipation

  • Poor appetite

  • Weight loss

  • Weakness

  • Confusion

  • Irregular heart rhythm 

  • Kidney stones

Should I take vitamin D2 or vitamin D3?

Whether you are at risk for a deficiency or aren't getting enough vitamin D through diet and sunlight, talking to your healthcare provider will help determine if a vitamin D2 or vitamin D3 supplement is right for you. 

At CareCard, we are passionate about helping make your prescription payments more affordable, saving members up to 85% on prescription drugs and medications. Learn how CareCard can help make your medication and supplement payments more manageable.

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Pharmacy names, logos, brands, and other trademarks are the property of their respective owners. Prescription savings may vary by prescription and by pharmacy, and in some cases may be discounted up to 85% off cash price*. Please note, this is NOT insurance. CareCard offers you the opportunity to find prescription discount prices, which ultimately depend on the provider. You are fully responsible for paying for all health care services but will be entitled to receive a discount from those health care providers in accordance with the specific pre-negotiated discounted rates. CareCard Inc. is not sponsored by or affiliated with any of the pharmacies identified in its price comparisons. This information is not mean to be a substitute for professional medical advice, treatment, or diagnosis. For additional information, please reach our customer support at 1-866-410-1217, Mon- Friday 9am – 5pm Est or email us at By using the CareCard prescription discount card or service, you are agreeing to CareCard’s Terms of Service.

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