The Lowdown on Magnesium for Chronic Pain, ME/CFS, Fibromyalgia, and More

Apr 27, 2023

Using magnesium to feel better is nothing new. Since the 1700s, people have used magnesium sulphate (Epsom salts) to relax muscles, lessen pain, and manage constipation. Apparently, Epsom salts don’t taste very good, so people searched for alternative forms of magnesium. There are over a dozen different types of magnesium, so I am often asked which type of magnesium is best to take. The answer is that it depends on how much you want to spend, what problem you are trying to solve, and what side effects you’re sensitive to.

One of the problems with reviewing any supplement is that research is often scant with only a few, often conflicting small studies for each effect.

Magnesium is everywhere, all the time. It is a critical cofactor for more than 600 enzymatic reactions in the body including:

  • breaking down food into essential nutrients,
  • producing energy,
  • building proteins and DNA,
  • nerve and muscle function of our neurons,
  • building neurotransmitters and hormones, and
  • bone health.

In this review, I’m focusing on effects that are relevant to people with ME/CFS, FM, ES, long COVID, and chronic pain.


Does magnesium help chronic pain?

Many people with chronic pain take magnesium supplements. But do they work? There is a strong rationale for using magnesium in chronic pain. The biological mechanism contributing to chronic pain is called central sensitization. It relies on activation of the NMDA receptor, which causes the brain to turn up the volume on pain. Magnesium blocks NMDA receptors and, therefore, could potentially prevent and reverse central sensitization. Magnesium also activates GABA receptors, a calming neurotransmitter. This is why some people find it useful for sleep.

Overall, research evidence that magnesium decreases pain—acute and/or chronic—is modest and contains a lot of gaps. A recent Cochrane review reports that 44% of studies for magnesium in migraine treatment were positive as were 50% of studies in other types of chronic pain, including fibromyalgia.

In a 2021 review, Boulis and colleagues found that five out of seven studies reported that magnesium helped improve fibromyalgia symptoms. Unfortunately, only two of the studies are the gold standard randomized controlled trials so, although encouraging, the level of evidence for magnesium is weak when it comes to improving these symptoms. More research is needed.

To cite one of the better-designed studies, Bagis and colleagues reported that women with fibromyalgia had lower magnesium levels than healthy women and that their fibromyalgia symptoms—pain and tenderness in particular—improved when they were given 300 mg of magnesium citrate daily.

In a 2008 study, Köseoglu et al. reported fewer migraines in women taking 600 mg of magnesium citrate daily compared to those on placebo. The participants’ accounts were supported by brain imaging.

What about leg cramps? I have recommended magnesium for years, and many people have told me that it helps them. I take it myself. When I look at the evidence, however, it is lacking. A Cochrane review in 2012 concluded that leg cramps do not significantly improve among people taking magnesium.

I thought for sure there would be some solid research about the use of magnesium in ME/CFS, given the critical role magnesium plays in energy production, but there isn’t. Just because something has a hypothetical rationale doesn’t mean it works. Despite this, many practitioners recommend magnesium as part of a mitochondrial protocol. For me, it has never made any difference. But we are all different, and if it works for you, this is more persuasive than any study result.


How do you know if you are low on magnesium?

Many people self-diagnose that they would benefit from magnesium supplements by the symptoms they experience. Magnesium deficiency is rare, but if severe, it can produce:

  • muscle pain and cramps,
  • anxiety,
  • depression,
  • tremor,
  • myoclonus,
  • heart arrhythmias,
  • fibrillation


Are low magnesium levels associated with chronic pain?

The problem is that it is hard to know for sure if someone is low in magnesium because measuring magnesium levels is difficult. Less than 1% of magnesium is found in the blood. The rest is in the tissues, especially the muscles and bones. So, if the blood level gets a bit low, the body recruits more from the tissues to keep the blood level steady—possibly at the cost of the tissue stores. It is claimed that hair analysis can help sort this out, but definitive research is lacking.

A few small studies suggest that people with fibromyalgia have lower concentrations of magnesium than healthy people with no pain. This is also reported in people with migraine headaches. And there is substantive evidence that up to 30% of people with Type 2 diabetes are low in magnesium. Perhaps magnesium supplementation should be considered if you have Type 2 diabetes.


What is in magnesium supplements, and does it matter which one you take?

Magnesium has a 2+ positive charge, which is always bound to a negatively charged molecule. In a magnesium supplement, the type of negatively charged molecule determines how well the magnesium will be absorbed and what health effects and side effects it will have. The good news is that magnesium is very safe. The only troubling side effect is loose stools, which for some people is the intended effect.

Among the magnesium supplements commonly recommended in ME/CFS and FM, there is virtually no research—only clinical experience to back up the recommendations.

Keep in mind that different magnesium supplements vary significantly in price from about 6 cents to over 30 cents per 150 mg capsule.

Mg Citrate is one of the cheapest forms of magnesium and has shown positive effects in a variety of studies. Whether you want to manage constipation or increase cellular magnesium levels, magnesium citrate is a good choice. Combining it with Vitamin C is even better for constipation. In my manual, I call this “Ellie’s guaranteed success formula.” There is a reason why magnesium citrate was used for decades as the prep for colonoscopies. It works!

Mg Lactate is well absorbed and is therefore easier on the stomach and bowels. This is a good choice for people who need to take large doses for things like muscle cramps and don’t want to get diarrhea.

Mg Malate is often included in supplements for fibromyalgia and chronic pain. This is because the anion, malic acid is part of the citric acid cycle and is thought to support energy production.

Mg Threonate is reported in one small study to be better absorbed by the brain and is, therefore, better at supporting brain function. And based on this study, significant claims have been made to justify a hefty price tag. It would be ideal to have a direct comparison with a cheaper form like Mg Citrate to see if the absorption and symptom outcomes are, in fact, superior.

Mg Glycinate contains the amino acid glycine as the anion. Glycine is the most common inhibitory neurotransmitter in the nervous system. Glycine is a gentle, non-addictive strategy to calm the brain and is often recommended for people with ME/CFS, especially at bedtime.

Mg Sulfate (Epsom Salts) are most commonly used as part of a hot bath. There are claims that magnesium is absorbed through the skin and increases muscle relaxation, but I was unable to find any research supporting this. Nevertheless, a hot bath with Epsom salts is a great bedtime routine. After a bath, the body lowers its temperature, and the decreasing temperature enhances sleep.

Because there is nothing to patent and recover research costs, there is never enough research on natural supplements. However, here are some findings that seem reliable:

  • Overall, it seems that as one takes more magnesium, relatively less is absorbed, so at a certain point it is not worth it to keep increasing the dose.
  • Organic magnesium such as taurate, citrate, bisglycinate are better absorbed than inorganic forms.
  • Powder and liquid are better absorbed than capsules and tablets.
  • Formulations with fewer non-medicinal additives are better for anyone who is sensitive.
  • Formulations with an enteric or phospholipid coating are better absorbed.
  • Magnesium is better absorbed in an acid environment. People on drugs to treat ulcers, such as proton pump inhibitors, may develop magnesium deficiency.
  • Magnesium taken with fermentable fiber increases absorption because the fermentable fiber is fermented into short-chain fatty acids that decrease the pH in the bowel and increase the absorption of magnesium and other minerals like calcium.


How much magnesium do we need?

The recommended daily intake of magnesium varies with age. Adult women need about 300 to 350 mg/day and adult men between 400 and 450 mg/day. What is the best way to achieve this? In my opinion, it’s always better, when possible, to get nutrition through real food. Sometimes supplements have unanticipated effects.

Fortunately, it’s easy to get enough magnesium through diet. The chart below from the National Institutes of Health (NIH) website gives some examples of how one ounce of seeds or nuts can supply one-third of the daily allowance. And these natural foods are packed with other great nutrition such as healthy fats, protein, and many other micronutrients.


Magnesium Content of Selected Foods

For those who want to learn more about magnesium, the NIH fact sheet is packed with useful information. 



If you’re taking magnesium supplements, they bind to some medications such as the drugs for osteoporosis and thyroid hormone, so always take magnesium 2 hours apart (before or after) medications.



There is modest evidence that magnesium has some positive effects on pain. Many of the studies use intravenous magnesium in acute and post-operative pain. Far fewer studies exist about the use of magnesium for chronic pain. And each of those studies used different types of magnesium and different protocols making it impossible to recommend any specifics.

On the other hand, magnesium is inexpensive and safe. It’s worth a try for anyone with chronic pain or fatigue. If you’re going to try something and are on a budget, I recommend magnesium citrate “to bowel tolerance.” This means increasing the dose until you notice soft stools and then pull back to a safe dose and wait to see if you feel better. Since at least two studies in pain used magnesium citrate 600 mg/day, that is a dose worth aiming for. If, after 2 months, you see no difference, it may not work for you. I would discontinue and put your efforts and supplement dollars elsewhere.


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Primary Sources (n.d.) Magnesium.

National Institutes of Health. (2022). Magnesium.

Pardo, M. R., Vilar, E. G., & Martín, I. S. M., & Martín, M. A. C. (2021). Bioavailability of magnesium food supplements: A systematic review. Nutrition, 89.