Yes, for most healthy adults ubiquinol is generally considered safe to take daily. Ubiquinol is the reduced form of coenzyme Q10 (CoQ10), and in clinical trials daily CoQ10 has been well tolerated for periods of weeks up to several years, including a 2-year trial at 300 mg a day. Side effects are usually mild, such as stomach upset or trouble sleeping, but CoQ10 can interact with warfarin and some other medicines, so talk to your healthcare provider first if you take medication.
Key Takeaways
- NCCIH reports no serious side effects of CoQ10; mild trouble sleeping or digestive upset may occur.
- Trials have used daily CoQ10 for up to two years at 300 mg a day, and reviews describe an observed safety level of 1,200 mg a day.
- Ubiquinol-specific safety studies are shorter: up to 300 mg a day for four weeks in healthy adults showed no safety concerns.
- Most studies use 90 to 390 mg a day; there is no official recommended dose.
- CoQ10 can reduce the effect of warfarin and may lower insulin needs. Ask your doctor or pharmacist before using it with these or other medicines.
- Safety in pregnancy and breastfeeding has not been established.
Evidence grade: Moderate. Many CoQ10 trials, including a 2-year randomized trial, report good tolerability, but studies of the ubiquinol form specifically are small and short.
What Is Ubiquinol?
CoQ10 is a compound your body makes and uses in the energy-producing part of every cell. NCCIH notes that the highest levels are in the heart, liver, kidneys and pancreas. CoQ10 exists in two forms: ubiquinone, the oxidized form, and ubiquinol, the reduced form. The two are continually converted back and forth inside cells as part of CoQ10's normal job in energy production and as an antioxidant.
Supplements are sold as either form. Because the body converts one into the other, the safety research on CoQ10 in general applies to both, while a smaller set of studies has looked at ubiquinol on its own. For a side-by-side look at the two forms, see CoQ10 ubiquinone vs ubiquinol.
What the Research Says About Daily Use
The question most people ask is whether taking it every day, for months or years, is safe. The research is reassuring for healthy adults.
| Study | Who and how long | Daily amount | Safety finding |
|---|---|---|---|
| Hosoe et al., 2007 | Healthy volunteers, single doses and 4 weeks | Ubiquinol 90, 150 or 300 mg | No clinically relevant changes in lab tests, vital signs, physical exams or ECG |
| Langsjoen and Langsjoen, 2014 | 12 healthy volunteers, 4 weeks of each form | 200 mg ubiquinone, then 200 mg ubiquinol | No side effects noted |
| Q-SYMBIO (Mortensen et al., 2014) | 420 adults with chronic heart failure, 2 years | CoQ10 100 mg three times a day (300 mg) | Authors concluded long-term use was safe |
| Hidaka et al., 2008 (safety review) | Animal and human safety data | Up to 1,200 mg in clinical trials | Low toxicity, no serious adverse effects; observed safety level 1,200 mg a day |
Short-term ubiquinol studies
The first ubiquinol safety study gave healthy volunteers 90, 150 or 300 mg a day for four weeks. There were no clinically relevant changes in standard lab tests, physical exams, vital signs or heart tracings, and no safety concerns up to two weeks after the study ended. In another small study, 12 healthy adults took 200 mg of each form for four weeks, and no side effects were noted.
Longer-term CoQ10 trials
The longest well-known trial, Q-SYMBIO, followed 420 adults with chronic heart failure for two years. Participants took 100 mg of CoQ10 three times a day alongside their usual care. The authors concluded that long-term CoQ10 use was safe in this group. This trial studied people with a heart condition under medical supervision, so it does not mean CoQ10 is a substitute for any medicine.
Safety reviews
A 2008 safety review pooled animal and human data. It found CoQ10 has low toxicity and does not cause serious adverse effects in people, and it set an observed safety level of 1,200 mg a day based on clinical trials. It also reported that supplements do not appear to shut down the body's own CoQ10 production, and that CoQ10 does not build up in blood or tissues after you stop taking it. The review's authors worked for a CoQ10 ingredient maker, so it is worth reading alongside independent sources such as NCCIH and the National Cancer Institute, which also report no serious toxicity.
Common Side Effects
Side effects are uncommon and usually mild. NCCIH lists insomnia and digestive upset. The National Cancer Institute adds that doses of 100 mg a day or more have caused mild insomnia in some people, and that other reported effects include rash, nausea, upper stomach pain, heartburn, headache, dizziness, irritability, sensitivity to light and tiredness. Raised liver enzymes have been seen in people taking 300 mg a day for long periods, but no liver toxicity has been reported.
Practical tips if you notice side effects:
- Take it earlier in the day if it affects your sleep.
- Take it with a meal. CoQ10 is fat-soluble and absorbed best with fat.
- If side effects continue, stop and talk to your healthcare provider.
How Much Is Typical?
There is no official recommended dose for ubiquinol or CoQ10. The National Cancer Institute reports that human studies have usually used 90 to 390 mg a day. Absorption is slow and limited: blood levels peak about 6 hours after a dose, and the elimination half-life is about 33 hours, so levels build over the first one to two weeks of daily use. In the small 4-week comparison study, 200 mg a day of ubiquinol raised total blood CoQ10 more than the same amount of ubiquinone. For the timeline, see how long CoQ10 takes to work.
An OPA Option: Ubiquinone Rather Than Ubiquinol
OPA CoQ10 Ubiquinone provides 200 mg of CoQ10 as ubiquinone in one capsule, with a cellulose vegetable capsule and rice flour as the other ingredients; a bottle of 30 capsules is a 30-day supply. Note that it is the ubiquinone form, not ubiquinol. The body converts ubiquinone to ubiquinol, and 200 mg a day sits within the 90 to 390 mg range used in most studies and below the 300 mg a day used in the 2-year trial. In one small study the same 200 mg dose of ubiquinol raised blood levels more than ubiquinone. The label suggests one capsule once daily, 20 to 30 minutes before a meal with water.
Safety and Interactions
CoQ10 is well tolerated by most adults, but it is not right for everyone without medical advice. Talk to your doctor or pharmacist before taking ubiquinol or any CoQ10 if you take:
- Warfarin or other blood thinners: CoQ10 can reduce the body's response to warfarin.
- Insulin or other blood-sugar-lowering medicines: CoQ10 may lower insulin needs, and some oral blood-sugar medicines lower blood CoQ10.
- Statins or gemfibrozil: these lower blood CoQ10 levels. Keep taking your medicine as prescribed and ask your pharmacist before adding CoQ10.
- Beta-blockers or other blood pressure medicines: ask whether CoQ10 is suitable alongside them.
- Chemotherapy or radiation therapy: NCCIH notes CoQ10 may not be compatible with some types of cancer treatment. Check with your oncology team.
Also talk to your healthcare provider first if you are pregnant or breastfeeding, since safety has not been established, or if you have surgery planned. Our guides on who should not take ubiquinol and medications that may not mix with CoQ10 go into more detail.
Frequently Asked Questions
Can you take ubiquinol every day long-term?
Most healthy adults can. CoQ10 has been taken daily in trials for up to two years without serious side effects, although ubiquinol-specific studies have been shorter. Review long-term use with your healthcare provider.
What is the recommended dose of ubiquinol?
There is no official recommended dose. Studies have usually used 90 to 390 mg a day.
Can ubiquinol interact with medications?
Yes. CoQ10 can reduce the effect of warfarin and may lower insulin needs. Statins, gemfibrozil and some blood-sugar medicines lower CoQ10 levels, and it may not suit some cancer treatments. Ask your doctor or pharmacist first.
Should ubiquinol be taken with food?
It can be taken with or without food, but CoQ10 is fat-soluble and absorbed best with fat, so taking it with a meal is usually better.
Is ubiquinol safe during pregnancy?
Safety during pregnancy and breastfeeding has not been established. Talk to your healthcare provider before taking it.
Is ubiquinol safer than ubiquinone?
No study shows one form is safer. They are two forms of the same compound that the body converts between, and both have been well tolerated in studies.
Sources
- National Center for Complementary and Integrative Health (NIH). Coenzyme Q10. Last updated 2019.
- National Cancer Institute (NIH). Coenzyme Q10 (PDQ), Health Professional Version. Updated 2024.
- Hidaka T, Fujii K, Funahashi I, Fukutomi N, Hosoe K. Safety assessment of coenzyme Q10 (CoQ10). Biofactors. 2008.
- Hosoe K, Kitano M, Kishida H, et al. Study on safety and bioavailability of ubiquinol (Kaneka QH) after single and 4-week multiple oral administration to healthy volunteers. Regul Toxicol Pharmacol. 2007.
- Mortensen SA, Rosenfeldt F, Kumar A, et al. The effect of coenzyme Q10 on morbidity and mortality in chronic heart failure: results from Q-SYMBIO: a randomized double-blind trial. JACC Heart Fail. 2014.
- Langsjoen PH, Langsjoen AM. Comparison study of plasma coenzyme Q10 levels in healthy subjects supplemented with ubiquinol versus ubiquinone. Clin Pharmacol Drug Dev. 2014.
- Mantle D, Dybring A. Bioavailability of Coenzyme Q10: An Overview of the Absorption Process and Subsequent Metabolism. Antioxidants (Basel). 2020.
- Bhagavan HN, Chopra RK. Coenzyme Q10: absorption, tissue uptake, metabolism and pharmacokinetics. Free Radic Res. 2006.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
