Coenzyme Q10

What is coenzyme Q10, and what does it do in the body?

Coenzyme Q (CoQ) is a key component of the electron transport chain in mitochondria and an antioxidant in cell membranes and lipoproteins. It is produced in all cells through an orderly pathway involving a multi-component mitochondrial protein complex. ^[1] The Cochrane review describes the molecule as a fat-soluble electron carrier. ^[5]

According to the review by Hernández-Camacho and colleagues, coenzyme Q10 has been found at lower levels in tissues in deficiency syndromes and aging as well as in some chronic diseases; this observation gave rise to the hypothesis that the supplement might ease the signs of aging or delay the onset of these diseases. The review proposes that there is evidence that the supplement favorably affects mitochondrial deficiency syndrome and signs of aging mainly through bioenergetic improvement, and that through its antioxidant effect it eases cardiovascular disease and inflammation; the same review also states that clinical studies with more participants and longer duration are needed for metabolic syndrome, diabetes, neurodegenerative diseases, kidney diseases and fertility. ^[1] That is, detecting a low level in a tissue does not show that the supplement improves that disease; this is kept separate below throughout as the difference between “role in the body” and “benefit of additional supplementation.”

Does statin use lower coenzyme Q10 levels?

The 2018 meta-analysis by Qu and colleagues pooled 12 randomized studies (1,776 participants) comparing statins with placebo. Statin therapy lowered circulating coenzyme Q10 level (standardized mean difference −2.12; 95% CI −3.40 to −0.84). The decrease was not found to be related to treatment duration; it was seen with both lipophilic and hydrophilic statins and with both low-to-moderate and high-intensity treatment. ^[2]

This result measures the circulating level; it does not show the level in muscle tissue. The authors interpreted the finding as a possible mechanism for statin-induced muscle complaints; this interpretation does not show that the supplement reduces the complaint. That question is addressed under a separate heading below. ^[2]

Is coenzyme Q10 found in foods?

The body produces coenzyme Q10 itself; foods are an additional source. In a study in Denmark, the average Danish diet was estimated to contain 3–5 mg of coenzyme Q10 per day, 64% of which came from meat and poultry. In the same study, when healthy volunteers were given a single 30 mg dose either within a meal or as a capsule, serum level rose significantly by both routes; the authors stated that coenzyme Q10 is significantly absorbed from foods. ^[14] This is an estimate based on one country’s diet and a small single-dose study; it does not reflect intake in Türkiye.

Ubiquinone or ubiquinol?

Two forms are seen in supplements: ubiquinone and ubiquinol; ubiquinol is the reduced form of ubiquinone. In an RCT published in 2026, 150 healthy adults took, for 8 weeks, commercial products at the label dose of ubiquinone, ubiquinol, geranylgeraniol, ubiquinol + geranylgeraniol, or placebo. Ubiquinone, ubiquinol and ubiquinol + geranylgeraniol raised plasma coenzyme Q10 level compared with placebo; there was no significant difference between ubiquinone and ubiquinol (p ≥ 0.15). All costs of the study were covered by a supplement company; the first author is on the same company’s scientific advisory board (according to the paper, the company had no role in design and analysis). ^[15] This data does not show that one form is clinically superior; the single study measured plasma level, not disease outcomes.

In whom does coenzyme Q10 supplementation work? Evidence summary

Detailed guideCoenzyme Q10 benefits: which claims are supported?→

Does coenzyme Q10 work in heart failure?

Q-SYMBIO is a multicenter, double-blind RCT comparing, in 420 people with moderate-to-severe heart failure, 100 mg of coenzyme Q10 three times daily added to standard treatment with placebo over 2 years. There was no significant change in the short-term endpoints at week 16 (NYHA class, 6-minute walk test, NT-proBNP). The long-term primary endpoint, major cardiovascular event, was seen in 15% in the coenzyme Q10 group and 26% in the placebo group (HR 0.50; 95% CI 0.32–0.80). Among the secondary endpoints, all-cause death was 10% versus 18% (p = 0.018). ^[3]

In the ISRCTN registry, the study’s sponsor is listed as a Danish manufacturer of coenzyme Q10 supplements; the funders are listed as the same company, an Italy-based international coenzyme Q10 association and a Japanese chemical company. ^[4]

The Cochrane 2021 review covered 11 studies (1,573 participants); all studies had unclear or high risk of bias in one or more domains. The review reported: for all-cause death RR 0.58 (95% CI 0.35–0.95; 1 study, 420 people; moderate-certainty evidence); for hospitalization due to heart failure RR 0.62 (0.49–0.78; 2 studies, 1,061 people; moderate certainty); for left ventricular ejection fraction a mean difference of 1.77 (0.09–3.44; 7 studies; very low certainty); results for exercise capacity, heart attack and stroke are uncertain. No study had examined quality of life with a valid scale. The authors’ conclusion: there is moderate-certainty evidence that coenzyme Q10 probably reduces death and hospitalization; however, there is currently no convincing evidence to support or refute its use in heart failure. ^[5]

Two details are important in reading these results. First, the death outcome is the data of Q-SYMBIO alone. Second, the 300 mg per day used in Q-SYMBIO is above the 200 mg/day maximum set for food supplements in Türkiye. ^[13] Treatment of heart failure is run by a physician with standard drugs; the studies examined coenzyme Q10 not in place of these but as a treatment added on top.

Does coenzyme Q10 help statin muscle complaints?

Two meta-analyses examining the same question reached opposite results.

• Banach et al. 2015: 6 RCTs, 302 people using statins. Plasma creatine kinase (CK) activity moved in the direction of an increase with coenzyme Q10 but was not significant (mean difference 11.69 U/L; 95% CI −14.25 to 37.63). There was a trend toward reduced muscle pain but it was not significant (standardized mean difference −0.53; 95% CI −1.33 to 0.28). The authors stated they did not suggest a significant benefit and that larger studies were needed. ^[6]
• Qu et al. 2018: 12 RCTs, 575 people (294 coenzyme Q10, 281 placebo). A reduction was found in muscle pain (weighted mean difference −1.60; 95% CI −1.75 to −1.44), weakness (−2.28), cramps (−1.78) and fatigue (−1.75); there was no decrease in plasma CK (0.09; −0.06 to 0.24). The authors said coenzyme Q10 could be a complementary approach. ^[7]

The two analyses were done with different numbers of studies and different pooling methods; both rest on small studies. Which is correct cannot be deduced from these two summaries; the effect is therefore read as “uncertain.” Continuing or changing statin treatment is the physician’s decision. A more recent 2025 meta-analysis (7 RCTs, 389 people) is presented in detail on the sub-page.

Does coenzyme Q10 prevent migraine?

The 2021 meta-analysis by Sazali and colleagues pooled 6 studies (371 participants) comparing coenzyme Q10 with placebo or as add-on treatment in adult migraine patients; crossover designs were excluded. There was no statistically significant reduction in migraine severity. A reduction was found in attack duration (mean difference −0.19; 95% CI −0.27 to −0.11) and attack frequency (mean difference −1.52; 95% CI −2.40 to −0.65). The authors of the meta-analysis reported no conflict of interest; 2 of the 6 included studies had reported funding from drug manufacturers. ^[8]

The 2012 guideline of the American Academy of Neurology (AAN) and the American Headache Society, reviewing studies between 1999 and 2009, had counted coenzyme Q10 among treatments in the “possibly effective” (Level C) class. However, the AAN board retired this guideline on 16 September 2015 because of serious safety concerns about butterbur, a product recommended in it, and announced that it no longer considered the guideline’s recommendations and conclusions valid. ^[9] For this reason, the 2012 classification is to be read not as a current recommendation but as historical context.

Did coenzyme Q10 show a slowing effect in Parkinson’s disease?

QE3 was a phase III, double-blind, placebo-controlled study conducted at 67 centers in North America. 600 people who had been diagnosed with Parkinson’s within the past 5 years and did not yet need dopaminergic treatment were randomized to placebo, 1,200 mg per day or 2,400 mg per day of coenzyme Q10; all received 1,200 IU of vitamin E per day. Follow-up was up to 16 months. The prespecified primary outcome was the change in total UPDRS (I–III) score. The study was stopped because the prespecified futility criterion was reached: the mean worsening in UPDRS score was 6.9 in the placebo group, 7.5 in the 1,200 mg group (p = 0.49) and 8.0 in the 2,400 mg group (p = 0.21); that is, the two active groups showed a slight unfavorable trend compared with placebo. The treatment was well tolerated and no safety problem was seen. ^[10]

Is coenzyme Q10 safe, and does it interact with drugs?

Safety data vary by study. In QE3, doses of up to 2,400 mg/day were well tolerated for up to 16 months. ^[10] In the Cochrane review, an RR of 0.70 (0.45–1.10; 2 studies, 568 people) was found for adverse event risk; the authors stated there was low-certainty evidence that adverse event risk may increase or make very little difference. ^[5]

For warfarin there are two different types of data. In the 1998 case report by Landbo and Almdal, a 72-year-old woman taking warfarin was reported to have a reduced response compared with before, and the response to warfarin returned to its former state when coenzyme Q10 was stopped; the authors mentioned the coenzyme’s chemical similarity to vitamin K as a possible explanation. ^[11] In the crossover RCT by Engelsen and colleagues, 24 outpatients on long-stable warfarin (21 completed the study) were given, in 4-week periods, 100 mg of coenzyme Q10 per day, 100 mg of Ginkgo biloba per day and placebo (with 2-week washouts in between). INR remained stable; the geometric mean weekly warfarin dose was 36.5 mg in the coenzyme Q10 period and 36.0 mg in the placebo period. The authors concluded that coenzyme Q10 did not affect the clinical effect of warfarin. ^[12] This study is small and short; it examines a single dose level and therefore does not definitively exclude the possibility of interaction.

What questions should be asked when evaluating the supplement?

A decision on a supplement rests not on a single number but on several questions. For what purpose: treatment of a disease such as heart failure or Parkinson’s, statin muscle complaints, or unclear fatigue? Is there a controlled study done for this purpose, and is its result favorable, uncertain or unfavorable? Is the amount used below the supplement limit in Türkiye (200 mg/day for ages 11 and over), or is the amount for which benefit was reported in studies above it? Is a drug such as warfarin being used, is the user pregnant or breastfeeding? ^{[13] [12]} Because the answers to these questions vary from person to person, the right step may differ in two people with the same complaint.

What is the status of coenzyme Q10 in Türkiye?

In Türkiye, coenzyme Q10 appears in the Restricted Substances List published by the Ministry of Agriculture and Forestry for dietary supplements. In the list dated 21/09/2026, chemical synthesis is specified as the source; the maximum daily intake is given as 200 mg for ages 11 and over and 100 mg for the 4–10 age group. ^[13] These limits apply to dietary supplements; some doses used in studies are above this (for example, 300 mg per day in Q-SYMBIO, 1,200–2,400 mg in QE3). The Dietary Supplements Communiqué (Takviye Edici Gıdalar Tebliği) also makes mandatory on the labels of these products the statement “not a medicine” and a warning that a physician should be consulted in case of pregnancy, breastfeeding, illness or medication use. ^[16] Safety data specific to coenzyme Q10 supplementation during pregnancy and breastfeeding are limited.

Detailed guideWhen to take coenzyme Q10? Fatty meal, split dose and duration→

This guide does not recommend a personal dose; in conditions such as heart failure, Parkinson’s, migraine or statin-related muscle complaints, the decision is made together with a physician.