Guide
Does vitamin D cause diarrhea, bloating or constipation?
Stomach pain and vomiting are described with too much vitamin D; diarrhea, gas and constipation are not reported in the trials we cite. What to try and when to stop.
The trials we cite do not report diarrhea, gas or bloating from vitamin D. Nausea, vomiting and abdominal pain are described with too much, from high blood calcium. At 2,000 IU a day for a median 5.3 years, the large trial identified no excess of adverse events.
What is documented: stomach symptoms from too much
A 2018 clinical review of vitamin D toxicity lists recurrent vomiting and abdominal pain among its most often noted symptoms, together with confusion, apathy, frequent urination, thirst and dehydration. They come from severe hypercalcemia (high blood calcium) caused by excessive long-term intake, usually of extremely high doses of concentrated preparations. Diarrhea is not among the symptoms that review names. So the documented route to stomach symptoms is too much vitamin D, not a normal dose.
In the trials we cite, the picture at ordinary doses is quiet. In VITAL (25,871 US adults aged 50 and over, 2,000 IU a day of vitamin D3 against placebo, median 5.3 years), no excess hypercalcemia or other adverse events was identified. At 3,200 to 4,000 IU a day, a meta-analysis of 22 randomised trials (12,952 adults, six months or longer) found a small excess of hypercalcemia, about 4 additional cases per 1,000 people, and no significant difference in kidney stones. We cite no trial that reports gastrointestinal symptoms as an outcome, so we cannot give a rate of diarrhea or constipation for any dose.
The symptoms people search for, one by one
| Symptom searched | What our sources say |
|---|---|
| Nausea, vomiting, stomach pain, upset stomach | Listed as symptoms of vitamin D toxicity (high blood calcium). Not reported as a problem at 2,000 IU in VITAL |
| Diarrhea, gas, bloating, "make you poop" | Not named in the toxicity review and not reported in the trials we cite; we cannot say yes or no |
| Constipation | Not named in the toxicity review; we cite no source that lists it, so we make no statement |
| Calcification of arteries | We cite no study that measured it. VITAL reported no difference in major cardiovascular events at 2,000 IU |
| Eye problems | We cite no study on it |
| Itching, rash, bruising | Not reported in the trials we cite. See the note on allergy below |
"We cite no study" is not the same as "it cannot happen". Individual reactions occur that trials do not capture. Treat any symptom that began after you started a product as worth noting down, and ask a clinician if it persists.
Why constipation or diarrhea may not be the vitamin
A softgel contains more than the vitamin. Ours is 50 mcg (2,000 IU) of vitamin D3 in a gelatin shell with glycerin, water, soybean oil and corn oil. A stomach reaction after starting a supplement could be due to the vitamin, to taking it on an empty stomach, to the oil or shell, or to something unrelated that happened to start at the same time, and we cannot tell which from outside. A change of habit is a reasonable first step: take it with a meal.
An itch or rash after starting any supplement can be an allergic reaction to any ingredient, including a shell or an oil. Stop taking it and seek medical advice; swelling of the face or throat, or trouble breathing, is an emergency.
Can I take vitamin D3 on an empty stomach?
You can, but a meal is the better habit. In a trial of 50 healthy older adults, a single 50,000 IU dose of vitamin D3 reached a peak blood level 32% higher (95% CI 11% to 52%) after a fat-containing breakfast than after a fat-free one. That compared two meals; no study we cite tests an empty stomach itself, and none tests whether eating changes stomach upset. If a softgel sits badly, take it with food. See when to take vitamin D.
When to stop and ask
Persistent vomiting, abdominal pain, unusual thirst or urination, weakness or confusion could be signs of high calcium. Stop the supplement and speak to a clinician. These are more likely if you stack products: the adult upper limit is 100 mcg (4,000 IU) a day from all sources, and our Personal Routines "D Complex" pill (125 mcg, 5,000 IU) must not be combined with our 50 mcg softgel. The numbers are in how much vitamin D is too much, and the broader safety picture in vitamin D side effects.
Our softgel
Electric Tiger Vitamin D3 has 50 mcg (2,000 IU) of vitamin D3 as cholecalciferol per softgel, one a day, as low as $15.35 a bottle on subscription. Its warning tells you not to exceed the recommended dose and to count vitamin D from other supplements.
Questions people ask
Why does vitamin D3 make me constipated?
We cannot say it does. No source we cite lists constipation. If it started with the supplement, try it with a meal, check your total vitamin D, and ask a clinician if it persists.
Does vitamin D3 make you poop, or cause gas, diarrhea or stomach problems?
Not reported in the trials we cite. Stomach pain and vomiting are described with too much vitamin D.
Can vitamin D3 cause nausea, or make you nauseous or upset your stomach?
Nausea is a recognised symptom of high calcium from excess vitamin D. At 2,000 IU the large trial identified no excess adverse events. Try a meal with it.
Can vitamin D3 cause calcification of arteries, or eye problems?
We cite no study on either, so we make no statement.
Can vitamin D3 cause itching, a rash or bruising?
Not reported in the trials we cite. An itch or rash can be an allergic reaction to any ingredient: stop and seek advice.
Sources
- Vitamin D Toxicity-A Clinical Perspective Too much vitamin D raises blood calcium, causing nausea, confusion, thirst and frequent urination; it is rare and usually follows very high doses.
- Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease In 25,871 older adults, 2,000 IU a day for a median 5.3 years did not lower cancer or heart-event rates versus placebo.
- Long-term supplementation with 3200 to 4000 IU of vitamin D daily and adverse events: a systematic review and meta-analysis of randomized controlled trials At 3,200 to 4,000 IU a day, a small share of people developed high blood calcium; kidney stones and deaths did not differ.
- Dietary fat increases vitamin D-3 absorption In 50 healthy older adults, one 50,000 IU D3 dose absorbed about 32% better with a fat-containing breakfast than a fat-free one.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
