Creatine for MCAS, ME/CFS, and chronic illness

Guest post by Lisa Dostmann

Why creatine matters especially for people with chronic illness

When I bring up creatine in clinical practice, the response is usually: "Isn't that for bodybuilders?" Yes, that's true, and at the same time: no, creatine can do a lot more, for "ordinary" people too, and in my view, for people in our community specifically.

I am writing this article primarily for people with MCAS and histamine intolerance, but much of it applies just as well to ME/CFS, long COVID, autoimmune conditions, EDS, and related conditions. The symptoms overlap, and the underlying reasons creatine might be relevant for these groups are largely the same.

First, there is the issue of inadequate creatine intake. The foods highest in creatine are salmon, herring, tuna, and beef, roughly 3 to 5 g per 500 g (!) of fresh weight. [1] These happen to be exactly the protein sources that people with MCAS and histamine intolerance often can't tolerate well, sometimes due to allergies, sometimes due to histamine content, and sometimes simply due to dietary preference. Anyone who doesn't tolerate meat and eats little fish structurally ends up with lower creatine levels than the general population.

Second, there is the symptom and comorbidity list: fatigue, brain fog, sleep disturbances, muscle loss, depression, osteoporosis, and more, unfortunately part of everyday life for people with MCAS, ME/CFS, long COVID, and autoimmune conditions generally. Creatine's effects on these particular issues have been studied in some depth, so I want to give an overview here.

If you would like a broader overview of amino acids in mast cell conditions first, there's already a short creatine section there, and this article is the more detailed version of that.

What is creatine, and how does the phosphocreatine system work?

Creatine is synthesized mainly in the liver, kidneys, and pancreas from arginine and glycine, with methionine, or more precisely its active metabolite SAMe, contributing a methyl group. This internal production pathway supplies around 1 to 2 g daily. [1] The rest comes from food, or doesn't.

Here is the key function: creatine is a fast-acting energy reserve. The phosphocreatine (PCr) system regenerates ATP (the body's universal energy currency) within milliseconds, without requiring oxygen. When ATP breaks down into ADP, phosphocreatine transfers a phosphate group back onto ADP, regenerating ATP in the process.

This is not just relevant to sports. Creatine matters anywhere energy metabolism is under strain, whether from increased demand (intense exertion, mental exhaustion) or from restricted energy production itself, low oxygen, ischemia, or disease states involving metabolic stress. [2] The brain, which has one of the highest energy demands in the body, is affected by this just as much as muscle tissue is.

Creatine, in other words, isn't just a muscle supplement. It is a central player in cellular energy metabolism, including in the brain.

Creatine research with a focus on chronic illness

Creatine supplementation research traditionally focused on athletes. As mentioned, it is one of the most extensively studied supplements out there, with a very strong safety profile. But the research questions have shifted considerably in recent years. Kreider and Stout's 2021 review explicitly focused on disease states, and there is now a growing body of clinical studies. What is still missing is data specifically on MCAS, ME/CFS, or long COVID, we still have to extrapolate there.

💡 Creatine in clinical research: areas covered in Kreider & Stout 2021 [2]

• Fatigue and post-exertional malaise
• Depression and mood
• Brain fog, cognition, sleep
• Fibromyalgia
• Osteoporosis and bone metabolism
• Muscle loss from immobilization
• Inflammation modulation (TNF-alpha, prostaglandin E2)
• Heat tolerance
• Neurodegenerative conditions (Parkinson's, Huntington's, Alzheimer's)
• Diabetes and glycemic control
• Pregnancy

Creatine and depression: the SAMe mechanism, and what the research shows

This is an area that genuinely interests me in my work, both because the underlying biochemical mechanism is elegant, and because depression, especially when it stems from chronic strain and inflammatory processes, is often so hard to treat effectively.

The methylation connection: Creatine biosynthesis is one of the body's biggest consumers of methyl groups. The body's central methyl donor is SAMe (S-adenosylmethionine), responsible for a huge range of reactions, including neurotransmitter synthesis and DNA methylation.

That makes creatine production one of the largest single consumers of SAMe in the entire body. The implication: when we supplement creatine, the body needs to produce less of it internally, easing the burden on the methylation cycle. The SAMe that's freed up becomes available for other reactions. [2] SAMe itself can be used as an antidepressant, so this connection is far from purely academic.

Is there direct clinical evidence for antidepressant effects of creatine?

Kreider and Stout (2021) explicitly list mood disorders as one of the areas with growing clinical evidence, both as a standalone approach and as an add-on to antidepressants. [2] Candow et al. (2026) confirm that mood disorders are an active area of research, but caution against drawing overly direct conclusions. [4] I share that caution, but given creatine's very strong safety profile, I think adding it alongside standard treatment is worth considering, particularly in vulnerable groups who likely aren't getting enough creatine from food in the first place.

One more thought on the MCAS connection: mast cells in the brain (perivascular mast cells) can trigger neuroinflammatory processes and affect the blood-brain barrier. Whether creatine directly intervenes here isn't established. But the combination of low baseline creatine from limited dietary tolerance, a strained methylation system, and depression makes creatine a reasonable thing to try.

Creatine for fatigue and ME/CFS: ATP recycling and its limits

ATP recycling is the core mechanism here. When phosphocreatine reserves are sufficient, the body can regenerate ATP faster and more sustainably. In sports, that translates to better performance. For fatigue-related conditions, the argument is different: it is about having a better buffer for ordinary daily demands.

Kreider and Stout (2021) explicitly discuss metabolically stressed states as a context where creatine can help, situations where energy metabolism is under pressure, independent of athletic performance. [2]

For post-exertional malaise (PEM), characteristic of ME/CFS, I want to be honest here: direct controlled data in this specific population is largely missing. The theory is plausible, a more robust ATP recycling system could better protect energy reserves and shift PEM trigger thresholds. But I'm not aware of any randomized controlled trials confirming this in ME/CFS specifically. That said, I personally use it fairly often as part of a combined treatment approach.

Creatine and brain fog: what the 2026 Candow paper says

Candow et al. (2026) gave their review a pointed title: "Creatine Supplementation and the Brain: Have We Put the Cart Before the Horse?" [4]

Creatine clearly plays a role in the brain's energy metabolism. Neurons and glial cells have high energy demands and actively use the phosphocreatine system. That much is undisputed.

The open question is: does oral supplementation actually raise creatine levels in the brain, and if so, in whom, to what extent, and is it clinically meaningful?

The answer turns out to be more complicated than hoped. The brain isn't a muscle, the blood-brain barrier regulates creatine transport differently than peripheral tissue. Candow et al. show that brain response depends heavily on individual baseline levels, and that methodological limitations (MR spectroscopy, short study durations) make clear conclusions difficult. [4]

The authors are fairly clear on who benefits most: people with low baseline levels, vegetarians, older adults, people with sleep deprivation, or cognitive impairment. [4] For people with normal baseline levels, the effects may be marginal.

Does creatine improve cognition?

There are signs of improved memory performance and processing speed, particularly under stress conditions. Under resting conditions, in healthy individuals with normal baselines, the effects tend to be fairly modest. [4] This fits with the broader picture, though, that cognitive performance in fibromyalgia patients, for example, has shown improvement with creatine supplementation.

Creatine levels are likely reduced after sleep deprivation

This is the finding I consider most relevant for our community. Sleep deprivation appears to lower brain creatine levels, and creatine supplementation has been shown to measurably improve cognitive performance under sleep-deprived conditions. [4]

For anyone whose sleep is disrupted by nighttime mast cell activation and histamine release, and who starts the day with brain fog as a result, this could be a genuinely useful lever. It hasn't been demonstrated specifically in our patient population yet, but it's the most plausible connection point in Candow's paper for this group.

Creatine and osteoporosis or osteopenia

The relationship between mast cells and bone health is becoming increasingly recognized within the MCAS community. Mast cells interact directly with osteoclasts and osteoblasts, and with chronic activation, can accelerate bone loss. This helps explain why osteoporosis shows up more often than expected in mast cell conditions, a topic that deserves its own dedicated article.

Creatine contributes here mainly through its combination with resistance training: studies show positive effects on bone density and muscle strength, particularly in postmenopausal women. [2] The mechanism: creatine allows for more intense training, and more intense training creates stronger mechanical stimulus on bone, which in turn promotes new bone formation. Creatine could therefore be a genuinely useful building block, especially when physical capacity is already limited.

Creatine for inflammation, heat tolerance, and immobilization-related muscle loss

TNF-alpha and inflammation: Santos et al. (2004) studied trained participants before and after a 30 km run, once with a creatine loading phase (5 days, 20 g), once without. Compared to the control group, the creatine group showed a 19% reduction in creatine kinase, a 61% reduction in prostaglandin E2, and a 34% reduction in TNF-alpha. [3]

Here is the honest context, though: healthy elite athletes after a 30 km run aren't our target population. The inflammatory dynamics in MCAS are different. Whether creatine has a similar effect on baseline, mast-cell-driven inflammation isn't known. What I do find noteworthy: TNF-alpha plays a central role in autoimmune conditions, it is the target of biologics like adalimumab. The idea that creatine could modulate part of this inflammatory response isn't far-fetched, but it is genuinely unproven in this population.

POTS, MCAS, and heat intolerance: could creatine help?

Prostaglandins are inflammatory mediators, and in MCAS, PGD2 in particular is one of the characteristic mast cell mediators. Creatine has been shown to improve cardiovascular and thermoregulatory responses to heat stress, partly through a hyperhydration effect. [1] For people who tolerate heat poorly (a common MCAS symptom), this is a plausible connection point, even though direct data is still missing.

Especially important for people with limited mobility

Muscle loss and immobilization: Creatine supplementation prevents the loss of the glucose transport protein GLUT4 in muscle during immobilization and reduces muscle atrophy. Op't Eijnde et al. (2001) simulated therapeutic immobilization (leg immobilization) and found that the creatine group experienced less muscle wasting and recovered muscle mass faster once immobilization ended. [5] For people who move very little due to illness, during fatigue flares, post-exertional malaise, or severe mast cell activation, this is a genuine lever against one of the most common downstream problems.

Side effects, and specifically: is it hard on the kidneys?

Creatine is sometimes portrayed in the popular press as harmful to the kidneys. That's factually incorrect, and I'm not saying that as a supplement enthusiast, but because the evidence here is unusually clear-cut.

Kreider et al. (2017), in their ISSN position stand, summarized the evidence: creatine at doses of 0.3 to 0.8 g/kg body weight daily during a loading phase, used in adults, children, and older adults over periods of up to five years and doses up to 30 g, showed no increase in kidney disease or other serious side effects. [1]

Established doses, recommended as far back as the 1980s by Swiss biologist Prof. Theo Wallimann, particularly for older adults, include something like 3 g daily.

Important caveat: Anyone with existing kidney disease should discuss starting creatine with their doctor first. Creatine raises blood creatinine levels, that's a normal metabolic effect, not kidney damage, but it can be misread as a red flag during routine bloodwork if the treating doctor isn't aware of this.

Self-synthesis: Creatine supplementation doesn't permanently suppress the body's own production, levels normalize again after stopping. [1]

Weight gain: the one consistent side effect. Creatine draws water into muscle tissue, causing an initial weight increase that has nothing to do with fat mass. For someone dealing with being underweight or muscle loss, this can actually be a desired effect. Knowing this in advance means it won't come as a surprise.

Creatine monohydrate or other forms: what's actually worth it

Short answer: creatine monohydrate is the first choice, since it is the only form of creatine with a genuinely solid safety and efficacy track record. [1]

Alternative forms (creatine HCl, buffered creatine sold as Kre-Alkalyn, creatine ethyl ester) are marketed with promises like better bioavailability or less water retention. The research doesn't convincingly support these claims compared to monohydrate in direct comparisons.

An exception for gastrointestinal sensitivity and MCAS, plus dosing recommendations

Creatine HCl is considerably more water-soluble than monohydrate, and in clinical experience, some patients genuinely tolerate it better. If monohydrate causes gastrointestinal issues, try splitting the dose first, skip the loading phase, and always take creatine with a meal. If that doesn't help, HCl is a legitimate alternative.

Cross-contamination is an underestimated risk for this group

Creatine monohydrate itself is synthetically produced and contains no allergens from milk, soy, egg, or wheat. The real risk lies in the manufacturing facility: many manufacturers produce creatine in the same facilities as whey protein, soy protein, or egg powder. This is why the familiar "may contain traces of..." warning appears on most tubs. Irrelevant for most users, but not for people with MCAS and allergies.

Creapure® (manufactured by AlzChem in Trostberg, Bavaria) is produced in its own dedicated, closed facility, and is, as far as I know, currently the purest creatine available on the market. What matters after that is who actually packages the powder. Products that clearly state Creapure® as their raw material and are packaged by a manufacturer with clean labeling practices are the safest choice for this particular group.

Creatine dosing and practical recommendations

These recommendations are drawn from the literature and don't replace individual guidance from your treating healthcare provider. Please always check with your care team.

Dosing:

• General health: 3 g daily, a dose recommended as early as 1984 by Wallimann, cited in Kreider 2017 [1]
• Targeted effects (muscle, cognition): 3 to 5 g daily, taken consistently
• Optional loading phase: 20 g daily for 5 to 7 days, then transitioning to a maintenance dose. This fills stores faster but isn't required. I generally don't recommend it, since most people in this group should be starting cautiously anyway.

Timing:

• Take creatine with carbohydrates, this improves absorption. [1] With a meal, for example, though a bit of glucose or maltodextrin works too.
• Time of day matters less than consistency.

Product choice:

• Favor products using Creapure® raw material (AlzChem, Trostberg), due to its dedicated production facility.
• No flavors, sweeteners, or dyes.

Conclusion: who does creatine make sense for?

Creatine isn't what a lot of people assume it is, it is actually one of the safest, most extensively researched supplements available, with an effect profile that is relevant to our community for several concrete reasons. Many people simply don't get enough of it through everyday food intake.

When it comes to the brain, I'll stay honest: the evidence is more interesting, and more open, than it's often made out to be. Candow et al. (2026) are right to ask whether we've put the cart before the horse.

References

[1]: Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18. DOI: 10.1186/s12970-017-0173-z

[2]: Kreider RB, Stout JR. Creatine in Health and Disease. Nutrients. 2021;13(2):447. DOI: 10.3390/nu13020447

[3]: Santos RV, Bassit RA, Caperuto EC, Costa Rosa LF. The effect of creatine supplementation upon inflammatory and muscle soreness markers after a 30km race. Life Sci. 2004;75(16):1917–24. DOI: 10.1016/j.lfs.2003.11.036

[4]: Candow DG, et al. Creatine and the Brain: Have We Put the Cart Before the Horse? Journal of Dietary Supplements. 2026 Jan 20. DOI: 10.1080/19390211.2026.2616440

[5]: Op't Eijnde B, Urso B, Richter EA, Greenhaff PL, Hespel P. Effect of oral creatine supplementation on human muscle GLUT4 protein content after immobilization. Diabetes. 2001;50(1):18–23. PubMed