What are the symptoms of fatigue?

Tired man at the computer

Coenzyme Q10 is an effective and safe supplement for reducing persistent fatigue symptoms [Tsai 2022].

Fatigue is different from ordinary tiredness, which is temporary and which is relieved by sleep. In contrast, fatigue is a persistent state of extreme tiredness that is not alleviated by rest. As a result, this persistent fatigue reduces the body’s capacity to perform daily activities. It affects both physical and mental functions. Commonly, it is characterized by a lack of energy, cognitive dysfunction (often referred to as brain fog), muscle weakness and pain, and disrupted sleep patterns.

What are the causes of fatigue?

Fatigue can result from a number of factors:

  • nutritional deficiencies
  • the effects of certain types of medication
  • stress
  • underlying medical disorders such as anemia and thyroid dysfunction

What types of disorder are characterized by fatigue?

To some degree, fatigue affects almost any type of illness. However, there is a group of so-called low energy disorders in which fatigue is a particular characteristic:

  • Gulf War Illness
  • Fibromyalgia
  • Myalgic encephalomyelitis/chronic fatigue syndrome
  • Long COVID

What are the biochemical causes of fatigue?

There is evidence for mitochondrial dysfunction, oxidative stress, and inflammation as common features causing fatigue. Often, patients with chronic fatigue syndrome, fibromyalgia, and long COVID exhibit abnormalities in mitochondrial function. Decreased ATP production, impaired mitochondrial respiration, abnormal mitochondrial DNA levels, immune dysregulation, increased oxidative stress, and chronic systemic inflammation perpetuate symptoms in these patients [Mantle et al, 2025].

In addition to their role in cellular energy provision, mitochondria also have a key role in the host innate immune response in first line defense against viruses. Certain types of viruses, notably those responsible for COVID, HIV, and Epstein-Barr syndrome are able to hijack host mitochondria. In so doing, they reprogram these organelles. They do this to evade the immune system and facilitate their own replication. This, in turn, causes mitochondrial dysfunction, severe energy deficiency, and increased oxidative stress and inflammation [Mantle et al, 2025].

How can Coenzyme Q10 benefit patients with fatigue?

There is a rationale for supplementary CoQ10 in the management of fatigue. The role of Coenzyme Q10 (CoQ10) in promoting normal mitochondrial function and in acting as an antioxidant and anti-inflammatory agent form the basis of this rationale.

Supplementation with CoQ10 has been shown to be beneficial in disorders such as Gulf War Illness, chronic fatigue syndrome, fibromyalgia, and long COVID. The supplementation results in improved mitochondrial function and reduced oxidative stress and inflammation [Mantle et al, 2025].

Gulf War Illness

In Gulf War Illness, supplementary CoQ10 improved physical function and self-reported health. It reduced the level of fatigue, pain, and muscle weakness [Golomb et al, 2014].

Chronic Fatigue Syndrome

Several studies have shown that CoQ10 supplementation can reduce fatigue and improve quality of life in individuals with chronic fatigue syndrome. Castro-Marrero et al [2021] reported that supplementation with CoQ10 and nicotinamide adenine dinucleotide (NADH) improved fatigue in chronic fatigue syndrome. A consensus report from the European network on chronic fatigue syndrome (EUROMENE consortium) has suggested supplementation with CoQ10 for symptoms such as fatigue, pain, and cognitive dysfunction in [Nacul et al, 2021].

Fibromyalgia

Fibromyalgia patients have depleted CoQ10 levels in tissues (typically 40–50% of the normal level). Hence, supplementation with CoQ10 can help reduce fatigue and chronic pain and can improve overall quality of life in fibromyalgia patients. A randomized, double blind, placebo-controlled study showed that 300 mg/day of CoQ10 for 40 days significantly reduced chronic pain and fatigue in fibromyalgia patients. In the study, there was a corresponding improvement in mitochondrial energy production [Cordero et al, 2013].

Supplemental CoQ10 may be particularly helpful in reducing pain and fatigue in fibromyalgia patients who are also taking pregabalin [Sawaddiruk et al, 2019]. In a prospective observational study, researchers supplemented 116 long COVID patients with 200 mg of CoQ10 and 200 mg of alpha-lipoic acid per day for 2 months. They administered placebos to 58 long COVID patients. Then, they assessed the patients’ fatigue severity using self-report questionnaires. Compared to placebo, the active treatment substantially reduced fatigue [Barletta et al, 2023].

Conclusion: Coenzyme Q10 and Fatigue

With regard to fatigue in more general terms, a meta-analysis by Tsai et al [2022] found supplementary CoQ10 significantly reduced fatigue in patients with a variety of disorders. Using higher dosages and longer treatment duration produced a greater reduction of fatigue.

As with many nutritional supplements, it is important to find a CoQ10 supplement with documented absorption and efficacy. There is much variation in the absorption and bioavailability of commercially available CoQ10 products.

Sources

Barletta MA et al. Coenzyme Q10 + alpha lipoic acid for chronic COVID syndrome. Clin. Exp. Med. 2023;23:667–678.

Castro-Marrero J et al. Effect of dietary Coenzyme Q10 plus NADH supplementation on fatigue perception and health-related quality of life in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: a prospective, randomized, double-blind, placebo-controlled trial. Nutrients. 2021;13:2658.

Cordero MD et al. Oxidative stress correlates with headache symptoms in fibromyalgia: coenzyme Q10 effect on clinical improvement. PLoS One. 2012;7(4):e35677.

Cordero MD et al. Can coenzyme Q10 improve clinical and molecular parameters in fibromyalgia? Antioxid. Redox Signal. 2013;19:1356–1361.

Golomb BA et al. Coenzyme Q10 benefits symptoms in Gulf War veterans: Results of a randomized double-blind study. Neural Comput. 2014;26:2594–2651.

Mantle D et al. Gulf War Illness, fibromyalgia, myalgic encephalomyelitis/chronic fatigue syndrome and long COVID overlap in common symptoms and underlying biological mechanisms: implications for future therapeutic strategies. Int J Mol Sci. 2025;26(18):9044.

Nacul L et al. European Network on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (EUROMENE): Expert consensus on the diagnosis, service provision, and care of people with ME/CFS in Europe. Medicina. 2021;57:510.

Sawaddiruk P et al. Coenzyme Q10 supplementation alleviates pain in pregabalin-treated fibromyalgia patients via reducing brain activity and mitochondrial dysfunction. Free Radic Res. 2019;53:901–909.

Tsai IC et al. Effectiveness of Coenzyme Q10 supplementation for reducing fatigue: a systematic review and meta-analysis of randomized controlled trials. Front Pharmacol. 2022;13:883251.

The information presented in this review article is not medical advice. Readers should not use it as medical advice.