# Coenzyme Q10

Source: https://onco.cc/technologies/coenzyme-q10/  
OnCo record `coenzyme-q10` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Coenzyme Q10 is an antioxidant supplement sold for heart health and energy. Studies in cancer fatigue are mixed, and in a breast cancer study women who took it before and during chemotherapy had a higher risk of the cancer coming back, so it is one to stop during treatment unless the team agrees.

## Summary

Coenzyme Q10 is made in every cell and has a role in mitochondrial energy production; as a supplement it is promoted for heart disease, statin muscle pain, migraine and cancer. Memorial Sloan Kettering's About Herbs summary reports that studies of whether it helps cancer-related fatigue are mixed, that findings on reducing treatment toxicity conflict, and that supplementation before and during treatment was associated with a higher hazard of recurrence in women with breast cancer. That association, from a study of supplement use in a chemotherapy trial, is observational, but it points the same way as the wider concern that antioxidants may blunt chemotherapy and radiotherapy; in a mouse model of lung cancer, ubiquinone reduced the effect of radiotherapy. The NCI PDQ summary on coenzyme Q10 gives the background history and the earlier small uncontrolled reports. Interactions listed by MSK: it resembles vitamin K and may weaken warfarin, although increased bleeding has also been reported with warfarin, and it slows clearance of theophylline. Side effects are infrequent and mild (nausea, diarrhoea, poor appetite).

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-11-04
- Also known as: CoQ10; Ubiquinone; Ubiquinol; Ubidecarenone
- Tags: complementary; supportive-care; evidence:harm
- Principle: An electron carrier in the mitochondrial respiratory chain and a lipid antioxidant; the antioxidant action that is the selling point is also the reason for concern during treatments that work partly through oxidative damage.
- Strengths: Mild side effects; Biologically plausible for heart failure, where some trials are positive
- Limitations: Associated with higher breast cancer recurrence when taken during chemotherapy; Fatigue trials mixed; Interactions with warfarin and theophylline

## Sources

- MSK About Herbs: Coenzyme Q10 (page last updated 29 September 2026): https://www.mskcc.org/cancer-care/integrative-medicine/herbs/coenzyme-q10
- NCI PDQ: Coenzyme Q10: https://www.cancer.gov/about-cancer/treatment/cam/hp/coenzyme-q10-pdq

## Connected records

- technologies: [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/), [Fatigue after cancer treatment: what actually works](https://onco.cc/technologies/cancer-related-fatigue-management/), [Milk thistle (silymarin)](https://onco.cc/technologies/milk-thistle-silymarin/), [Selenium supplements](https://onco.cc/technologies/selenium-supplements/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- fronts: [Chemotherapy](https://onco.cc/fronts/chemotherapy/), [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)

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