Despite interest in health and wellness rising, it’s estimated that at least 42% of the US population doesn’t get enough vitamin D. Insufficiency and outright deficiency in the so-called sunshine vitamin (based on our ability to synthesize vitamin D through the absorption of UVB rays) is a growing global problem.

This is a serious issue, given that adequate vitamin D intake is necessary for immune system function, energy production, reducing inflammation, growing and maintaining our bones, and metabolizing glucose. Chronic vitamin D deficiency can lead to rickets in children and osteoporosis in adults. Further, there may be a connection between low vitamin D levels and health issues like diabetes, obesity, high blood pressure, and autoimmune disease.

While it’s easiest to get sufficient vitamin D from sun exposure and foods like fatty fish and dairy milk, modern lifestyles make this harder to achieve than it sounds. 

As such, vitamin D supplements are commonplace, although their efficacy varies based on quality. Joining the mix are vitamin D injections. Trying to correct a nutrient deficiency with a shot has become an increasingly popular option (it probably doesn’t hurt that celebs keep posting pictures of themselves hooked up to vitamin IV drips).

So, are these injections worth your time (and money)?

Vitamin D Injections 101

There are two different forms of vitamin D:

  • Ergocalciferol (Vitamin D2)
  • Cholecalciferol (Vitamin D

The latter is what we produce when exposed to the sun’s rays, and it’s also what intramuscular vitamin D shots contain. We need this micronutrient to help our bodies absorb calcium and phosphorus, which are essential for strong bones.

Injection dosages vary, but typically contain around 200,000 to 300,000 IU and can range as high as 600,000 IU. Because vitamin D3 injections aren’t regulated in the US, you can get them at a range of locations. Clinical beauty spas offer them alongside treatments like laser vein therapy and Botox, and holistic health practitioners may also have them on their menu.

But why would anyone opt for an intramuscular injection when they could just take a pill or walk outdoors?

Well, for people with severely low vitamin D levels, a single injection may feel like an easier route to achieving balanced serum levels than taking weeks of oral supplements. from the drugstore.

How Long Does It Take for a Vitamin D Injection to Work?

The amount of time it takes to boost your vitamin D levels usually depends on how deficient you were to begin with, whether your D levels were too low due to malabsorption issues, and other aspects of your overall health profile.

However, one 2017 study found that a single injection left volunteers with statistically significant elevated serum levels at both six and twelve weeks after the shot. The volunteers in a 2018 study, meanwhile, showed statistically meaningful higher levels of vitamin D within 72 hours compared to those given a placebo.

How Often Can You Get Vitamin D Injections?

How frequently you can get vitamin D injections depends on your body’s needs. However, one older study found that a single annual so-called megadose, at 600,000 IU, succeeded in normalizing the vitamin D levels in participants with deficiency ranging from mild to severe. 

More recently, a 2015 study showed that at least 70% of participants receiving either a 600,000 IU or 200,000 IU dose still had corrected levels of vitamin D two months after the shot, and maintained elevated levels of the vitamin six months after the initial dose.

What does this mean for you?

First, there is no one-size-fits-all guideline for how frequently you can get vitamin D injections, but more isn’t necessarily better. In fact, due to the potential health risks (more on that in a moment), it’s imperative not to overdo your intake. The most judicious route may be to get a single injection, have your serum levels tested a few months onward, and then decide on appropriate next steps.

How Long Do Vitamin D Injections Last?

Again, this will likely depend on individual health factors, but a 2017 study looking at the effects of a single 200,000 IU injection found a significant increase in serum levels of the vitamin fourteen weeks after participants got their shot. And a 2018 study demonstrated that a 600,000 IU dose raised and maintained patients’ serum levels both one month and six months after it was administered.

It’s likely safe to conclude that vitamin D shots last a significant stretch and do not need to be administered frequently.

Are Vitamin D Injections Safe?

Since vitamin D injections aren’t regulated by the FDA, you’ll have to trust the medical spa or other establishment where you’re having yours administered.

It’s also worth noting that vitamin D is a fat soluble vitamin. This means it’s absorbed through our lymphatic system and stored in your liver, fat tissue, and muscle longer than water soluble vitamins, which have to be frequently replenished. 

Because vitamin D aids the absorption of calcium, excess intake can become toxic, leading to a state called hypercalcemia (too much calcium), which can cause dehydration, kidney stones, muscle weakness, nausea, and vomiting, and general pain.

At its absolute worst, too much vitamin D has also been known to cause renal failure and soft tissue calcification. A 2018 review of vitamin D toxicity case reports revealed several problematic cases involving excess doses delivered via injection.

One patient landed in the hospital after repeat shots within a two-week period, and a group of 15 patients aged 42 to 85, who were prescribed 600,000 IU injections and subsequently showed symptoms including fatigue, vomiting, renal dysfunction, dehydration, and altered sensorium (this can entail confusion, memory loss, poor decision making, and/or emotional disturbance).

No Shot? No Problem

Getting 20 minutes of direct sunlight per day allows your body to make sufficient levels of vitamin D3.

If you’ve weighed the pros and cons and decided a vitamin D jab isn’t for you, don’t worry. There are plenty of other effective ways to maintain healthy levels of this essential micronutrient.


20 minutes of direct sunlight daily, with 40% of your skin exposed and no sunscreen, is likely all you need for your body to make sufficient levels of vitamin D3. If you go this route, however, you’ll of course need to weigh the benefits against the risks regarding UV sun damage.


Vitamin D is trickier to obtain from food than from the sun, but it’s doable. Foods with high levels of vitamin D include fatty fish, dairy milk, egg yolks, and fortified foods like orange juice and breakfast cereals. Getting adequate vitamin D can be difficult if you follow a vegetarian or vegan diet—that’s where supplementation comes in.


The market is flooded with vitamin D pills, capsules, and gummies. However, these supplements don’t always deliver the dose of nutrients they advertise. When you swallow supplements, your digestive system breaks them down before the nutrients get to your liver. By the time the vitamins are released into your bloodstream, you’re left with a fraction of the original dose. 

Fortunately, your gut and upper arm aren’t the only places you can absorb nutrients. 

Arguably the most efficient route for vitamin D is under your tongue—also known as the sublingual method. The capillaries in your mouth are ultra-absorbent and provide a direct pathway to your bloodstream. Research has shown sublingual vitamins to be just as effective (if not more) than injections and oral supplements. You can get sublingual vitamin D from lozenges, drops, sprays, and even vitamin-fortified toothpaste.

Are Vitamin D Injections Right For You?

Vitamin D injections are relatively new to the supplement scene, at least for everyday folks. Based on the current research, a jab in the arm probably isn’t necessary to get your vitamin D levels up to par. 

You might be able to do the trick with dietary adjustments, supplements, or more time in the sunshine, all of which can boost your health without breaking the bank.