Guide
Does CoQ10 cause diarrhea, bloating or constipation?
What the sources report on CoQ10 and nausea, gas, diarrhea, bleeding and bruising, and what they don't tally.
Stomach complaints such as nausea have been reported with CoQ10, but a 2006 safety review found they were no more common at 1,200 mg a day than at 60 mg, so they could not be tied to dose. A 2022 meta-analysis of 13 trials reported one gastrointestinal event among 602 people given CoQ10. Gas, bloating and constipation weren't tallied separately in our sources.
What the sources reported
The 2006 risk assessment of ubiquinone trials, written by the Council for Responsible Nutrition (an industry trade body), concluded that nausea and other gastrointestinal effects could not be causally linked to CoQ10 because they showed no dose-response (Hathcock 2006). A 2022 meta-analysis of 13 randomised trials in 1,126 participants reported a single gastrointestinal adverse event among the 602 given CoQ10 (Tsai 2022). A 4-week study of ubiquinol at 90 to 300 mg a day found no clinically relevant changes in labs, vital signs or ECG, and was run by the product's manufacturer (Hosoe 2007).
These are group results. They don't rule out a reaction in one person, and none of them reported diarrhea, bloating, constipation, gas or heartburn as separate figures that we could read. We found no safety study of our capsule.
Bleeding, clots and blood thinners
People ask about blood clots, bleeding and bruising a lot. We found no study in our sources reporting that CoQ10 causes any of them. One trial gave CoQ10 100 mg a day for 4 weeks to 24 outpatients on stable long-term warfarin: INR and warfarin dose stayed stable, and the authors concluded it did not change warfarin's clinical effect (Engelsen 2003). It was small and at half our capsule's dose, so it is not a green light. Our label says to ask a physician before use if taking medication, especially blood thinners. See CoQ10 and medications.
Our label
Electric Tiger CoQ10 200 mg directs one capsule once a day, 20 to 30 minutes before a meal, or as directed by your healthcare professional; as low as $16.31 a bottle on subscription. We found no trial comparing CoQ10 on an empty stomach with CoQ10 with food, so we can't say which is gentler. The warning on the bottle: do not exceed the recommended dose; ask a physician before use if pregnant or nursing, under 18, taking medication or with a medical condition.
Questions people ask
Can CoQ10 cause nausea? Can it make you nauseous?
Nausea is the kind of complaint the 2006 review looked at, and it found no dose-response (Hathcock 2006). It doesn't say it never happens. If it does, stop and ask a pharmacist.
Does CoQ10 cause gas, bloating or heartburn?
We found no source that quantifies them. We can't say CoQ10 causes or doesn't cause them.
Does CoQ10 cause diarrhea or constipation?
The review above covers "other gastrointestinal effects" together and found no link to dose. It doesn't separate diarrhea from constipation, so we can't either.
Can I take CoQ10 on an empty stomach?
No trial we found tests it. Our supplier's directions say before a meal. If it upsets your stomach, ask a pharmacist whether to change when you take it. See the best time to take CoQ10.
Does CoQ10 cause blood clots, bleeding or bruising?
See above: we found no report that it does. Tell your prescriber if you take warfarin or another blood thinner before starting.
Can CoQ10 cause fatigue?
None of the safety sources we read lists fatigue as an adverse effect. If you feel worse after starting any supplement, stop and ask.
Can CoQ10 cause miscarriage?
We found nothing in our sources on this and give no guidance on pregnancy. Our label says to ask a physician before use if you are pregnant or nursing.
Where is the rest of the safety picture?
CoQ10 side effects, who should not take CoQ10 and how much is too much.
Sources
- Risk assessment for coenzyme Q10 (Ubiquinone) A 2006 review of the clinical literature found no dose-related side effects in studies from 60 to 1,200 mg a day.
- Effectiveness of Coenzyme Q10 Supplementation for Reducing Fatigue: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Pooling 13 trials in 1,126 people, CoQ10 lowered fatigue scores modestly versus placebo, with larger effects at higher doses and longer durations.
- Study on safety and bioavailability of ubiquinol (Kaneka QH) after single and 4-week multiple oral administration to healthy volunteers In healthy volunteers, 90 to 300 mg a day of ubiquinol for 4 weeks raised blood levels without lab or ECG changes; it was not compared with ubiquinone.
- [Effect of Coenzyme Q10 and Ginkgo biloba on warfarin dosage in patients on long-term warfarin treatment. A randomized, double-blind, placebo-controlled cross-over trial] In 24 people on stable warfarin, 100 mg a day of CoQ10 for 4 weeks did not change INR or warfarin dose.
*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.
