The short version
- Up to 91% of people with ME/CFS in the United States remain undiagnosed, according to a 2021 specialist consensus paper in Mayo Clinic Proceedings.
- That consensus paper records that the US and other governments and major healthcare organisations have withdrawn graded exercise therapy and cognitive behavioural therapy as the treatment of choice for ME/CFS.
- A 2025 systematic review of 14 dietary supplement studies in 809 people with ME/CFS found a high risk of bias in most, and concluded that methodological limitations prevent firm conclusions.
- Six of those 14 studies reported adverse effects from the supplements tested, including nausea and insomnia.
- Among primary-care patients presenting with tiredness, 18.5% had depression, 4.3% serious somatic disease and 2.8% anaemia across 26 studies, which is why a clinical work-up comes before any supplement decision.
Every supplement company gets these messages. Some version of: I have been exhausted for two years, doctors have found nothing, what should I take. It is the hardest email to answer honestly, because the honest answer sells nothing.
Here it is anyway.
First, the word matters
Myalgic encephalomyelitis, also called chronic fatigue syndrome, is a defined illness with diagnostic criteria, not a description of being tired. A 2021 consensus paper in Mayo Clinic Proceedings, written by 21 clinicians who specialise in it, records that clinical guidance has been scarce, obsolete or potentially harmful, and that up to 91% of patients in the United States remain undiagnosed. The 2015 National Academy of Medicine diagnostic criteria have been adopted by the CDC.
Two things in that paper deserve to be much better known. First, the United States and other governments, along with major healthcare organisations, have withdrawn graded exercise and cognitive behavioural therapy as the treatment of choice. Second, after acute COVID-19 a significant percentage of people remain ill for many months with an illness similar to ME/CFS.
The defining feature is post-exertional malaise: symptoms that reliably worsen after exertion, often a day or two later. That is why the well-meaning advice to push through is not merely useless here. It is the wrong instruction.
What the supplement evidence actually looks like
A 2025 systematic review pulled together 14 studies in 809 people. Its assessment of the field is unsparing: heterogeneous designs, and a high risk of bias in most of them, largely from missing data and selection bias.
Some interventions did show significant reductions in fatigue — L-carnitine with guanidinoacetic acid, oxaloacetate, a CoQ10 and selenium combination, NADH, and NADH combined with CoQ10. The review's own conclusion is that methodological limitations and inconsistent results prevent firm conclusions. Six of the studies noted adverse effects, including nausea and insomnia.
An earlier systematic review of 17 studies covering 14 different interventions found that many showed no therapeutic benefit at all, with improvements in fatigue reported for NADH, probiotics, high-cocoa-polyphenol chocolate, and NADH combined with coenzyme Q10. Its conclusion: insufficient evidence.
Notice what is not on either list. Not the ingredients that dominate the energy category. Not B vitamins, not adaptogens, not mushroom blends. The compounds with the faintest positive signals here are mostly mitochondrial cofactors tested in small, biased studies, and even their reviewers will not stand behind them.
The thing we will not do
We are not going to reposition anything we sell as a chronic fatigue product. Not because the category is unprofitable — it is extremely profitable, which is exactly why so many brands quietly drift into it with words like "cellular energy" and "mitochondrial support". A structure/function claim written carefully enough to pass a regulator can still be a promise to a desperate person.
If you have ME/CFS, no supplement on our site treats it, and none has been shown to.
Before you assume that is the diagnosis
Long-lasting fatigue has a differential, and it is worth working through with a clinician rather than around one. A systematic review of 26 primary-care studies of patients presenting with tiredness found depression in 18.5%, serious somatic disease in 4.3%, anaemia in 2.8% and malignancy in 0.6%.
None of that means your exhaustion is imaginary. It means the sequence matters: a proper work-up, including your thyroid, ferritin and B12 deficiency, before anyone concludes there is nothing to find. And "nothing on the standard panel" is not the same as "nothing wrong" — ME/CFS is diagnosed clinically, by criteria, not by a blood test that comes back abnormal.
What we would actually say
Find a clinician who knows the 2015 criteria and takes post-exertional malaise seriously. Ask specifically about pacing, which is the management approach the specialist consensus supports, rather than a graded exercise programme. Be wary of anyone — a brand, a clinic, a protocol — who is confident. The published record does not support confidence.
If you want to try something with your clinician's knowledge, the compounds with signals in the reviews are the ones named above, and you should go in knowing the evidence behind them is weak, the trials are small, and adverse effects including nausea and insomnia were reported. That is not a recommendation. It is the most useful thing we can honestly tell you, and we would rather say it than sell you a bottle with a photograph of a sunrise on it.
Good questions
What supplement is best for chronic fatigue syndrome?
There isn't one. Two systematic reviews covering 14 and 17 studies both concluded the evidence is insufficient, with a high risk of bias in most trials. A few compounds showed signals, mainly mitochondrial cofactors, and their own reviewers will not stand behind the results. Anyone confidently recommending a product for ME/CFS is going beyond the published record.
Is chronic fatigue syndrome a real illness?
Yes. It has formal diagnostic criteria published by the National Academy of Medicine in 2015 and adopted by the CDC, and a specialist clinical consensus on how to diagnose and manage it. The problem is not that it is unreal; it is that up to 91% of US patients remain undiagnosed and clinical guidance has historically been poor.
Should I try exercising more to build my energy back up?
Not without specialist advice, and not on the old graded exercise model. Post-exertional malaise, where symptoms reliably worsen after exertion, is the defining feature of ME/CFS, and major health organisations have withdrawn graded exercise therapy as the treatment of choice. Ask your clinician about pacing instead.
My blood tests came back normal. Does that mean nothing is wrong?
No. ME/CFS is diagnosed clinically against defined criteria, not by an abnormal blood result. A normal panel rules out several other causes, which is useful, and then the conversation should continue rather than stop. If your clinician treats a clean panel as the end of the discussion, it is reasonable to seek someone familiar with the current criteria.
Why won't you recommend anything?
Because the evidence does not support a recommendation, and this is a group of people who have already spent a great deal on things that did not work. We would rather lose the sale than add to that. If we ever have a product with real trial evidence in this population, we will say so with the numbers attached.
Is long COVID the same thing?
Not identical, but overlapping. The specialist consensus notes that a significant percentage of people remain ill for many months after acute COVID-19 with an illness similar to ME/CFS, and that those who do not fully meet the criteria may still benefit from the same clinical approaches. That is a conversation for a clinician who is following this literature.
Sources
- Bateman L, Bested AC, Bonilla HF, Chheda BV, Chu L, et al. Myalgic encephalomyelitis/chronic fatigue syndrome: essentials of diagnosis and management. Mayo Clin Proc, 2021. View study
- Dorczok MC, Mittmann G, Mossaheb N, Schrank B, Bartova L, et al. Dietary supplementation for fatigue symptoms in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review. Nutrients, 2025. View study
- Campagnolo N, Johnston S, Collatz A, Staines D, Marshall-Gradisnik S. Dietary and nutrition interventions for the therapeutic treatment of chronic fatigue syndrome/myalgic encephalomyelitis: a systematic review. J Hum Nutr Diet, 2017. View study
- Stadje R, Dornieden K, Baum E, Becker A, Biroga T, et al. The differential diagnosis of tiredness: a systematic review. BMC Fam Pract, 2016. View study
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
