Coenzyme Q10

Several findings below come from clinical populations rather than healthy adults, and each paragraph names the group. Grades are proposals per outcome; the evidence grading method explains what each grade requires, and the evidence matrix compares CoQ10 with other compounds.

Does CoQ10 reduce fatigue?

Pooled trials in mixed groups suggest so [1]. A 2022 meta-analysis (a study that pools the results of many trials) of 13 randomized controlled trials with 1,126 participants found CoQ10 reduced fatigue scores compared with placebo, with a Hedges' g of -0.398 (95% confidence interval -0.641 to -0.155) [1]. Hedges' g is an effect size, the difference between groups in standardized units. The analysis pooled healthy and diseased participants; the authors report the effect pointed the same way in both, but the abstract gives no separate estimate for healthy adults [1].

The reduction was significant for products containing CoQ10 alone, not for combination products, and in a meta-regression higher daily doses and longer use went with larger reductions [1]. Across the 602 participants given CoQ10, the trials recorded one adverse event, a gastrointestinal one [1].

Evidence in healthy adults is thin. In a small double-blind, placebo-controlled crossover trial in healthy volunteers, self-rated fatigue on a visual analog scale was lower than with placebo after a long, fatiguing cycling task and the recovery period at the higher of two CoQ10 doses, and cycling speed held up better late in the task [2]. PubMed lists an erratum for this trial that we could not read, so only its design and direction of effect are reported here [2].

An earlier systematic review of 16 studies found that 10 reported significantly less fatigue with CoQ10, in healthy people and in several clinical groups, and its authors called for larger trials with longer follow-up [3]. Evidence is mixed in some clinical groups: a 2026 meta-analysis in people with depression, a clinical population, found no significant benefit for fatigue, based on only 2 trials (SMD -0.33, 95% CI -1.38 to 0.72) [4]. Results in clinical groups may not apply to healthy adults. The energy goal page compares other compounds graded for fatigue.

Does CoQ10 improve endurance or exercise performance?

Pooled trials do not show a change in aerobic capacity [5]. A 2026 meta-analysis of 14 randomized controlled trials (of CoQ10 and related analogs) with 433 subjects found that oral CoQ10 raised blood CoQ10 but did not affect maximal oxygen uptake (VO2max, a standard measure of aerobic fitness) or blood lactate [5]. It did lower creatine kinase, a blood marker of muscle damage [5].

A 2024 meta-analysis of 28 randomized controlled trials with 830 adults found creatine kinase fell by 50.64 IU/L after CoQ10, along with other muscle-damage markers [6]. Its authors caution that most of the studies were run in Asia, which limits how far the results generalize [6]. A lower blood marker is not the same as better performance.

Single trials point in different directions. In a placebo-controlled trial with 9 people per group taking ubiquinone-10 or placebo for 22 days, including 5 days of high-intensity anaerobic training, the placebo group improved anaerobic cycling performance significantly more than the CoQ10 group, and VO2max did not differ [7]. In a 12-week double-blind trial in 40 robust older adults (average age 74; one author consults for Pharma Nord), 400 mg a day raised plasma CoQ10 but did not change mitochondrial function, VO2max or physical performance compared with placebo [8].

Reviews read the same literature differently. A 2023 systematic review of 16 studies in athletes aged 17 and older concluded that 30-300 mg of CoQ10 increased plasma antioxidant activity and anaerobic performance [10], while a 2022 systematic review of exercise studies called the data inconclusive but still described CoQ10 as an interesting molecule in sports performance [9]. Evidence is mixed: the pooled estimate for VO2max is null, and the small trials that measured performance went in both directions [2][7].

In 2010 the European Food Safety Authority (EFSA) concluded that a cause and effect relationship had not been established between CoQ10 and increased endurance capacity or performance, noting that no references were provided from which conclusions could be drawn [28]. More compounds are graded on the physical performance goal page.

Does CoQ10 lower blood pressure?

Evidence is mixed, and it comes from people with high blood pressure or cardiometabolic conditions rather than healthy adults [11][12]. A 2016 Cochrane review found 3 eligible double-blind trials in primary hypertension, a clinical population, and pooled 2 of them (50 participants) after judging the third at unacceptably high risk of bias [11]. CoQ10 did not significantly change systolic (-3.68 mm Hg) or diastolic (-2.03 mm Hg) blood pressure compared with placebo, and the authors rated this moderate-quality evidence that CoQ10 has no clinically significant effect [11].

A 2022 meta-analysis of 26 studies with 1,831 patients with cardiometabolic disorders found systolic pressure fell by 4.77 mmHg compared with control [12]. The reduction followed a U-shaped dose-response curve, largest at about 100-200 mg a day, and the evidence was rated moderate quality for systolic and low quality for diastolic pressure [12]. A 2026 meta-analysis of 20 randomized trials in people with prediabetes or type 2 diabetes found no significant effect on systolic or diastolic pressure [13].

An older 2007 meta-analysis reported a 16.6 mm Hg fall in systolic pressure in the CoQ10 groups of its 3 randomized trials (120 patients), but this was a before-and-after change within those groups, and 8 of its 12 studies were open-label [14]. NCCIH says the small amount of evidence available suggests CoQ10 probably does not have a meaningful effect on blood pressure [22], and EFSA found a blood pressure claim not substantiated [28]. Results in people with high blood pressure may not apply to healthy adults.

Does CoQ10 affect blood vessel function?

Pooled trials report an improvement on one measure [15][16]. Trials measure endothelial function, the function of the blood vessel lining, with flow-mediated dilation (FMD) [16]. A 2024 meta-analysis of 12 studies with 489 subjects found FMD rose after CoQ10 (weighted mean difference 1.45), the change was larger at higher doses, and the effect appeared after 8 weeks [15].

A 2012 meta-analysis of 5 randomized controlled trials in 194 patients with and without established cardiovascular disease found improved FMD (SMD 1.70) but no improvement in nitrate-mediated dilation, a second measure [16]. Neither abstract reports a separate estimate for healthy adults, and the 2024 abstract does not describe its populations [15][16].

What the evidence does not show

Cognition: as of November 11, 2026 we found no randomized trial with a cognitive primary outcome of CoQ10 in healthy adults (PubMed and Europe PMC searches, November 11, 2026). A 12-week trial in older adults measured cognitive function, but its abstract reports no result for it [8]. EFSA concluded that a cause and effect relationship had not been established between CoQ10 and normal cognitive function [28].

Energy metabolism: EFSA reached the same conclusion for normal energy-yielding metabolism [28], and the Great Britain nutrition and health claims register lists CoQ10 energy, cognitive function, blood pressure and endurance claims as non-authorised [27].

Tissue levels: higher blood levels did not mean higher muscle levels in older adults. After 12 weeks, plasma CoQ10 rose while levels in muscle tissue and isolated mitochondria were unchanged [8].

CoQ10 from food is absorbed slowly and to a limited extent because it is hydrophobic and a large molecule, according to a pharmacokinetics review written by researchers employed by Tishcon Corporation [18]. The same review reports peak blood levels about 6 hours after a dose and an elimination half-life of about 33 hours, and says solubilized formulations show better bioavailability [18]. LiverTox notes that because CoQ10 is lipid soluble, it is often given with lipids or vitamin E to improve absorption [30].

Supplements raise blood levels in trials: pooled exercise trials found higher blood CoQ10 [5], and a meta-analysis in cardiometabolic disorders found circulating CoQ10 rose by 1.62 μg/mL compared with control [12].

A safety review written by researchers employed by Kaneka Corporation reports that supplemental CoQ10 does not change the body's own production and does not build up in plasma or tissues after supplementation stops [17].

NCCIH says no serious side effects of CoQ10 have been reported, and mild side effects such as sleep problems or digestive upsets may occur [22]. LiverTox reports that CoQ10 is well tolerated even in high doses, with side effect rates no higher than with placebo; side effects are mostly mild, short-lived gastrointestinal upset, nausea, headache, dizziness and fatigue [30]. LiverTox found no convincing reports of liver injury despite decades of wide use and gives CoQ10 a likelihood score of E, an unlikely cause of liver injury [30].

Trial reports are limited but consistent with this. In the 2022 fatigue meta-analysis, one gastrointestinal adverse event was recorded among 602 people given CoQ10 [1], and the Cochrane blood pressure review states that "in one of three trials reporting adverse effects, coenzyme Q10 was well tolerated" [11].

A 2008 safety review written by researchers employed in the functional food ingredients division of Kaneka Corporation concluded that CoQ10 has low toxicity and does not cause serious adverse effects in humans [17]. It reports an observed safety level of 1,200 mg a day per person from clinical trial data, and an acceptable daily intake of 12 mg per kg of body weight a day derived from a 52-week rat study [17]. Health Canada's monograph requires no statement on known adverse reactions [25].

Upper amounts by market: Health Canada's monograph caps licensed products at 300 mg a day [25], and Australia caps internal-use medicines at 300 mg of ubidecarenone a day [29]. We found no US, UK or EU upper intake level for CoQ10 in the sources checked (November 11, 2026).

The sources below raise five medicine groups in connection with CoQ10, as an interaction, a label caution or an effect on CoQ10 levels: anticoagulants, insulin, blood pressure medicines, some cancer treatments and statins [19][22][25][29].

Anticoagulants: NCCIH says CoQ10 may interact with the anticoagulant (blood thinner) warfarin [22]. Health Canada requires products providing more than 100 mg a day to advise people taking blood thinners to ask a health care practitioner before use [25]. Australia requires internal-use medicines containing CoQ10 to carry the label warning "Do not take while on warfarin therapy without medical advice" [29].

Insulin: NCCIH says CoQ10 may interact with the diabetes drug insulin [22].

Blood pressure medicines: Health Canada requires every CoQ10 product to advise asking a practitioner before use if taking blood pressure medication [25].

Cancer treatment: NCCIH says CoQ10 may not be compatible with some types of cancer treatment [22].

Statins: in a meta-analysis of 8 placebo-controlled treatment arms, these cholesterol-lowering medicines lowered plasma CoQ10 by 0.44 μmol/L, and its authors say the clinical relevance is unclear [19]. Whether CoQ10 eases statin-associated muscle symptoms is disputed. A 2018 meta-analysis of 12 randomized trials with 575 patients found less muscle pain than with placebo but no change in creatine kinase [20], while a 2020 meta-analysis of 7 trials with 321 patients found no benefit on muscle pain and no effect on whether people stayed on their statin [21]. NCCIH says the overall evidence does not support CoQ10 reducing statin-related muscle pain [22]. These are clinical populations.

If you take any of these medicines, talk to your doctor or pharmacist before combining them with CoQ10.