Coenzyme Q10 (CoQ10)
A supplement that supports the cell’s energy machinery. It is biologically plausible for the fatigue of long COVID and low-risk to try — but the strongest test of CoQ10 on its own came back negative.
Short version: CoQ10 (especially the ubiquinol form) helps mitochondria make energy, so it is a reasonable, low-risk thing to try for fatigue. But a randomized long-COVID trial of CoQ10 alone did not beat placebo; the more encouraging signals come from ME/CFS and from combinations. Worth discussing with a clinician — especially if you take a blood thinner.
Why it might help fatigue and the mitochondria
Much of the fatigue and exercise intolerance in long COVID traces back to mitochondrial dysfunction — the cell’s power plants running below capacity, and falling further after exertion. CoQ10 sits at the heart of that machinery: it ferries electrons along the mitochondrial respiratory chain and also acts as a fat-soluble antioxidant, mopping up the oxidative stress that comes with faltering energy production. “Top up the cofactor the energy chain depends on” is the rationale. The ME/CFS literature, which overlaps heavily with long COVID, is where most of the supporting work has been done.
What the evidence shows
It is genuinely mixed, and weaker for long COVID specifically than the marketing suggests.
- In ME/CFS, randomized placebo-controlled trials of CoQ10 combined with NADH reported improvements in fatigue, cognitive fatigue and sleep, with signs of restored cellular energy markers — though the largest trial did not reach a clear between-group difference, so the effect is modest and it is a combination, not CoQ10 alone.1
- In long COVID specifically, a randomized, placebo-controlled crossover trial of high-dose CoQ10 (500 mg/day) on its own found no benefit over placebo — both groups improved — and the authors concluded CoQ10 should not be recommended as a treatment for post-COVID condition. This is the most directly relevant evidence, and it is negative.2
- Combinations (for example CoQ10 with alpha-lipoic acid) have produced striking observational results, but those studies are uncontrolled and wide open to placebo and selection effects, so the eye-catching numbers should be read with real caution.3
Net: plausible mechanism, decent signal in ME/CFS and in combinations, but the controlled evidence for CoQ10 by itself in long COVID is essentially negative. A reasonable low-downside experiment — not a proven treatment.
What taking it is actually like
It is a daily capsule; the ubiquinol form is absorbed better than the older ubiquinone. CoQ10 is generally very well tolerated — occasional mild stomach upset, headache, or trouble sleeping if taken late. The important interaction is that it can blunt the effect of warfarin (lowering the INR), and it may add to the effect of some blood-pressure medicines, so it belongs on the list you share with your clinician or pharmacist. As an unregulated supplement, strength and quality vary between brands, and there is no routine monitoring beyond the usual INR checks if you are on a blood thinner. Dose and suitability are individual — this is not a dosing guide.
What we don’t know
Whether the people most likely to benefit are specifically those with demonstrable mitochondrial dysfunction (rather than long COVID broadly); the best form and dose; and whether the apparent gains from pairing CoQ10 with NADH or alpha-lipoic acid are real and additive or mostly placebo. And as everywhere on this site: if post-exertional malaise is present, no supplement substitutes for pacing.
References
Every reference is free to read in full.
- Coenzyme Q10 plus NADH supplementation in ME/CFS — randomized, double-blind, placebo-controlled trial (Castro-Marrero et al., 2021).
- High-dose coenzyme Q10 versus placebo in post-COVID-19 condition — randomized phase 2 crossover trial (Lancet Regional Health – Europe, 2022).
- Mitochondrial dysfunction and coenzyme Q10 supplementation in post-viral fatigue syndrome — overview (IJMS, 2024).