You can’t get magnesium through the skin

A report describing delivery of magnesium through the skin for the treatment of fibromyalgia has just appeared in the Journal of Integrative Medicine. The title of the report is, Effects of transdermal magnesium chloride on quality of life for patients with fibromyalgia: a feasibility study. It was conducted by doctors at the Mayo Clinic, which carries a certain amount of legitimacy. However, close reading of this report shows shockingly poor quality of this study.

It is true that magnesium deficiency has been found in patients with fibromyalgia (especially if levels other than serum or plasma are measured, i.e. ionized or RBC) Fibromyalgia is a syndrome of unknown cause, which is characterized by chronic pain, fatigue, depression, and sleep disturbances. Some studies have found that the lower the level of magnesium, the more symptoms patients were having. There is an association between fibromyalgia and migraine headaches and those of our patients who have both conditions often report relief of both migraines and fibromyalgia with oral magnesium supplementation or intravenous infusions.

Several companies promote products that promise to deliver magnesium into the body through the skin. The oldest one is Epsom salts, which is magnesium sulfate. Taking a warm bath with Epsom salts surely feels relaxing, but there is no evidence that magnesium penetrates through the skin.

The Mayo clinic study enrolled forty postmenopausal female patients with the diagnosis of fibromyalgia. Each was given a spray bottle containing a 31% solution of magnesium chloride (and “a proprietary blend of trace elements”) and asked to apply 4 sprays per limb twice daily for 4 weeks. They were also asked to complete various questionnaires. Only twenty-four patients completed the study, with 4 dropping out because of skin irritation. At week 2 and week 4 most were significantly improved.
The authors concluded that their study “suggests that transdermal magnesium chloride applied on upper and lower limbs may be beneficial to patients with fibromyalgia”. This was a very small and unblinded study with many dropouts, which means that no conclusions can be made. It is very surprising why the authors did not measure magnesium levels before and after the treatment, which would make the study much more valuable.

The company that sponsored the study has a product they’d like to sell to the unsuspecting public and it will certainly use this “study” and the Mayo Clinic name to sell their miracle spray. The Mayo Clinic is a highly respected institution and I hope they will not allow its name to be associated with such poor quality marketing studies.