test-CoQ10 Side Effects
Vitamins & Supplements
CoQ10 Side Effects
Amy Sunderman, MS, RD • February 13, 2022

What are the Side Effects of CoQ10?

Educating yourself about the supplements you take is smart. What you put into your body matters and can affect your health in many ways! Some nutritional supplements, including CoQ10, can proudly lay claim to a host of potential benefits. But it’s still a good idea to take a closer look and learn about what’s in the supplements you take, how to choose quality supplements and if there are any potential side effects or interactions between supplements and medications when taken together.

In the case of CoQ10, the potential benefits usually far outweigh the potential for mild side effects, but there are some possible interactions to keep in mind.

Benefits of CoQ10 Infographic

What is CoQ10?

Coenzyme Q10 is found naturally in many living things, including plants, bacteria, animals and even humans. It’s officially classified as an antioxidant, but our cells use it for the production of adenosine triphosphate (ATP), which helps give cells energy and vitality for healthy growth and maintenance.1 Because CoQ10 is essential, it’s often considered a vitamin-like nutrient, but our bodies make some of it naturally so it isn’t classified as a vitamin.

But just because we make some CoQ10 doesn’t mean we make enough of it for optimal health. And as we age, our natural CoQ10 production starts to decline.2 We still make it when we get older, just not as much of it, and that may cause some health concerns. There are also medications and other factors that may affect how much CoQ10 our bodies produce. CoQ10-rich foods and CoQ10 supplements may help keep your levels of this vital coenzyme up and promote wellbeing.

What is CoQ10 Used For?

CoQ10 promotes health at a cellular level, supporting cellular energy and working hard as an antioxidant to fight free radicals and damage from oxidative stress. It may also help promote a healthy heart and nervous system, and support muscle strength and physical performance.3

CoQ10 deficiencies have been linked to other nutritional deficiencies, as well as genetic defects, chronic issues and mitochondrial concerns.2 Low CoQ10 levels may also be a side effect of statin treatments.1

CoQ10 Uses and CoQ10 Benefits

CoQ10 for Cardiovascular Health
CoQ10 may have “significant cardiovascular protective effects.”5 It may also provide additional support for people taking statins, reducing muscle-related statin side effects and allowing people who need statins to take them consistently.5 CoQ10 supports overall heart health in many important areas.5

CoQ10 for Nervous System Health

Early research suggests that high doses of CoQ10 might be beneficial for people concerned about nervous system health and body movement.3 CoQ10 may have an influence on autonomic nervous activity in healthy subjects.4 The autonomic nervous system regulates some very important, involuntary functions of the body including the heart, smooth muscles, intestinal tract muscles and glands.6

CoQ10 and Healthy Muscles

Skeletal muscles need CoQ10 for energy, growth and repair.7 And many physicians recommend CoQ10 supplements to people who take medicines that may cause muscular symptoms.7 CoQ10 may help relieve weakness and other muscle concerns related to taking statins, since those symptoms may be linked to a statin-induced CoQ10 deficiency.7 Statins can block the body’s ability to produce CoQ10.7

CoQ10 and Physical Performance
Coenzyme Q10 plays an important role in energy production, making it a candidate for physical performance studies, but the jury is still out on confirmed benefits. One study suggests CoQ10 may increase endurance during exercise, helping healthy individuals (both trained and untrained) exercise for longer periods of time.8 However other studies concerning CoQ10 and physical performance have produced mixed results.3

Some lesser-studied CoQ10 uses include weight management, skin health and reproductive health. Read CoQ10 Benefits: What You Need to Know to learn more.

CoQ10 Dosage

There is no established daily intake of CoQ10, but a typical daily dose is 100 mg to 200 mg per day.9 Studies have used doses ranging from 50 mg to 1,200 mg per day, and even up to 3,000 mg per day in some cases, usually split up over several doses throughout the day.7,9 Here are some CoQ10 dosages used in studies for particular areas of health.

CoQ10 Deficiency–150 mg to 2,400 mg per day.10

Mitochondrial support–150 mg to 160 mg per day, or 2 mg for every kg of body weight per day. In some cases, doses may be gradually increased to 3,000 mg per day.10

Heart health–100 mg per day for up to four months, or 2 mg per kg of body weight, per day, for up to a year.10

Nerve support–400 mg per day for 12 weeks.10

Muscular support–100 mg per day for three months.10

CoQ10 is best taken with a meal or alongside an oil-based supplement, like krill oil or coconut oil, because it is fat-soluble. The presence of fat will help your body break CoQ10 down to absorb it.5 Always follow the usage instructions provided on any supplement you use, and consult with your healthcare provider if you intend on exceeding the recommended dosage.

Is CoQ10 Safe?

CoQ10 has a great safety record when taken as directed.7 It is considered “likely safe” for most adults and “possibly safe” for children when taken orally, but never give CoQ10 to a child without consulting with the child’s physician first.10 Also, don’t take CoQ10 while you are pregnant or nursing unless directed by your doctor.

If you are taking medications or are undergoing treatment for any health concerns, always check with your doctor before starting a new supplement. CoQ10 is generally well-tolerated, but there are some potential side effects and interactions.10

What Are the Potential CoQ10 Side Effects?

The safety record of CoQ10 makes it a great choice for supporting health and wellbeing for those who need it. However, as with any supplement, some individuals do experience CoQ10 supplement side effects. Side effects of CoQ10 are rare and typically mild. They can include diarrhea, nausea and heartburn.9 There have also been instances of individuals taking 100 mg or more of CoQ10 per day experiencing changes in mood or digestive wellness.11

CoQ10 Supplement Side Effects

The CoQ10 in Swanson Health supplements is an all-natural trans isomer derived from yeast fermentation. Supplements provide a more concentrated form of the coenzyme than what’s found in most CoQ10 food sources and CoQ10 supplements, and they rarely cause problems. But as mentioned above, there have been some rare, mild side effects from CoQ10. If you are concerned about CoQ10 supplement side effects, talk to your doctor or pharmacist first, especially if you are taking prescription medications, because there are some potential interactions. Some common interactions are listed below.

CoQ10 Drug Interactions

We have included some common drug interactions below, but let your doctor know about any supplements you are taking and discuss any possible interactions between your supplements and other medications you take or treatments you are receiving.

Blood pressure
CoQ10 may increase the effects of some medications used to lower blood pressure.10

Cigarette smoking depletes your body of stored CoQ10.10

CoQ10 may interfere with blood pressure control both during and after surgery, so stop taking it at least two weeks before a surgical procedure.10

Blood Thinners

CoQ10 may decrease the effectiveness of blood thinners. If you are taking a blood thinner, talk with your doctor before taking CoQ10.3

Some commonly prescribed drugs may deplete the body’s CoQ10 levels, including clonidine, glyburide, hydrochlorothiazide, nortriptyline, doxepin, glipizide and beta-blockers.7

CoQ10 Supplements

There are two forms of CoQ10 supplements: ubiquinone and ubiquinol. Ubiquinol is the active form of CoQ10, and your body converts ubiquinone into ubiquinol. They are both great options, but some medical experts say that younger people may get more benefits from ubiquinone, and older people may benefit more from ubiquinol.5

Swanson Health CoQ10 Supplements

Swanson Ultra CoQ10 (200 mg CoQ10)
Swanson's CoQ10 200 mg ubiquinone supplement produces adenosine triphosphate (ATP) in the body, which creates energy and supports cardiovascular function.

Swanson Ultra CoQ10 100 (100 mg CoQ10)

Delivers 100 mg of Swanson Ultra CoQ10 as ubiquinone per softgel to promote cardiovascular wellness and support ATP production in the body.

Swanson Ultra Ubiquinol (100 mg CoQ10)

Pharmaceutical-quality ubiquinol in the first stabilized, bio-identical CoQ10 supplemental form of ubiquinol, the same form as 90% of the CoQ10 stored in the body. This supplement achieves higher elevations of circulating CoQ10 in the bloodstream with just a fraction of the dose and promotes healthy heart function. This supplement is also available in a smaller bottle, see Swanson Ultra Ubiquinol (100 mg CoQ10, 60 count)

Swanson Ultra Ubiquinol - Maximum Strength (200 mg CoQ10)

The next generation of CoQ10 supplementation! This bioavailable form of CoQ10 is ready for immediate utilization by your body and achieves higher elevations of circulating CoQ10 in the bloodstream with just a fraction of the dose.

Want to learn more about benefits, uses and natural food sources of Co10? Read CoQ10 Benefits: What You Need to Know and CoQ10 Food Sources

Amy Sunderman, MS, RD, Director of Science & Innovation Registered Dietitan

About Amy Sunderman, MS, RD

Amy is a registered dietitian, nutritionist and author with more than 20 years of experience in the supplement industry. Amy is passionate about dietary supplements and the health benefits they offer. She enjoys working to find novel nutritional ingredients with strong clinical research behind them to drive innovation and provide health-promoting products to consumers.

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.


1. Coenzyme Q10. National Institutes of Health. Read source

2. Coenzyme Q10. Journal of Pharmacy & BioAllied Sciences. Read source

3. Coenzyme Q10. Mayo Clinic. Read source

4. Influence of CoQ10. National Library of Medicine. Read source

5. CoQ10: What are the Heart Health Benefits? Cleveland HeartLab Read source

6. Medical Definition of Autonomic Nervous System. MedicineNet. Read source

7. CoQ10 Supplement. How Stuff Works. Read source

8. Effects of Coenzyme Q10 Supplementation. Journal of the International Society of Sports Nutrition. Read source

9. Coenzyme Q10. WebMD. Read source

10. Coenzyme Q10 Overview, Uses, Side Effects, Interactions, Dosing. WebMD. Read source

11. Coenzyme Q10: Topic Overview. WebMD. Read source