Vitamin D3 Side Effects

Vitamin D3 is one of the most important nutrients out there. It’s called “the sunshine vitamin” because vitamin D synthesis depends on our skin getting enough exposure to the sun. However, most of us don’t get enough vitamin D3 these days. There are a few reasons for this: most of us work all day inside, sometimes without even a window in the room. And the media keeps reminding us of all the dangers of too much skin exposure, including skin cancer, so that even when we’re not at work, many of us try to avoid going out in the sun.

All this means that taking vit D3 supplements is more important than ever. But this puts us at risk for another potential downside: vit D3 side effects. We need to get our vit D3 somehow, so taking a supplement is important. Just make sure to watch out for these signs and symptoms.

What Are the Vitamin D3 Side Effects?

People disagree about just how much vitamin D3 you can take before experiencing side effects. The recommended daily amount is fairly low—about 200-600 IU, depending on your age. But many people think this number is way, way too low. Personally, I take between 1000-2000 IU per day. But every now and then, I take a few days off, to avoid toxicity symptoms. Because vitamin D3 is a fat-soluble vitamin, it can build up in your adipose tissue. Some vitamin D3 side effects include:

  • Reduced appetite
  • Thirst
  • Metallic taste in the mouth
  • Muscle issues
  • Frequent urination
  • Constipation
  • Diarrhea and vomiting
  • Itchy skin
  • Sore eyes
  • Fatigue           

People with heart problems, kidney disease, or high calcium or phosphorus might be at risk for additional complications if they take a vitamin D3 supplement. Ask your doctor about these.

More Vitamin D3 Side Effects

Vitamin D3 might interact with some medications, including:

  • Atorvastatin
  • Nifedipine
  • Verapamil
  • Amlodipine
  • Diltiazem
  • Nicardipine
  • Digoxin
  • Thiazide
  • Isoniazid
  • Estrogen

There are also some medications that lower your blood levels of vitamin D3, including rifampin, mineral oil, orlistat, bile acid sequestrants, and some anti-seizure medications. If you take these, you might be at risk for vit D3 deficiency. Speaking of which…

Vitamin D3 Side Effects Compared to Vitamin D3 Deficiency

These side effects sound bad, but are they as bad as not getting enough vitamin D? When you look at the wide-ranging function of vitamin D, the answer is definitely not. Vitamin D3 deficiency can lead to rickets in children, which is when their bones become weak and soft. Insufficient vitamin D might also help lead to:

  • depression (especially seasonal affective disorder, or SAD)
  • diabetes and obesity
  • heart disease
  • multiple sclerosis
  • high blood pressure
  • several kinds of cancer, including breast, colon, and prostate cancers
  • and overall mortality rates

Those are some seriously bad things.

Who Is Most At the Highest for Deficiency?

Because darker skin is not as good at absorbing vit D from sunlight, African Americans and other dark-skinned people are more at risk for deficiency. So are people living in the far north, where there’s a lot less sunlight. If you fall into one of these camps, consider taking a vitamin D3 supplement.


So what are you to do? Should you avoid taking vitamin D3 supplements? Or is it worth the risk to avoid a deficiency? My opinion (and let me add a disclaimer here: I’m not a doctor, so talk to one before you make any big changes to your diet) is that you should absolutely take a vitamin D3 supplement. The reason is that few of us get enough naturally occurring vitamin D. Just take it in moderation, and watch out for signs of toxicity.

Thanks for reading about vitamin D3 side effects. You might also be interested in reading about vitamin B complex side effects, vitamins for energy, and cinnamon supplements. Have a great one.