Transdermal Magnesium: Lack of Evidence for Clinical Benefits
There is insufficient evidence to support the use of transdermal magnesium for any clinical purpose as it has not been proven to effectively deliver magnesium through the skin. 1
Scientific Evidence on Transdermal Magnesium
Transdermal magnesium products (creams, oils, sprays, and bath salts) have gained popularity through marketing claims suggesting they provide better absorption and fewer side effects than oral supplementation. However, these claims lack substantial scientific support:
The 2017 review in Nutrients concluded that the propagation of transdermal magnesium is scientifically unsupported, describing it as "myth rather than reality" 1
While one small pilot study (n=25) showed a clinically relevant increase in serum magnesium with a 56mg/day magnesium cream, statistical significance was only achieved in a subgroup of non-athletes 2
A more recent 2023 single-arm, open-label pilot study in CKD patients reported reduced neuropathic symptoms with transdermal magnesium, but importantly, serum magnesium concentrations did not change significantly during the study 3
Established Therapeutic Uses of Magnesium
In contrast to transdermal applications, intravenous and oral magnesium have well-documented therapeutic uses:
Intravenous Magnesium:
- Effective for severe asthma exacerbations not responding to conventional treatment 4
- Treatment of torsades de pointes and ventricular fibrillation/tachycardia associated with acute myocardial infarction 5, 4
- Management of hypomagnesemia 4
Oral Magnesium:
- Proven effectiveness for treating magnesium deficiency in cardiovascular disease and diabetes mellitus 1, 6
- Potential benefits for metabolic syndrome, glucose and insulin metabolism, dysmenorrhea, and leg cramps during pregnancy 6
Skin Drug Delivery Principles
The skin's primary function is to prevent entry of exogenous substances into the body, with the stratum corneum serving as the main barrier due to its lipophilicity and cellular cohesion 5. For transdermal delivery systems to be effective, they must overcome this barrier function, which requires specific physicochemical properties that magnesium salts do not possess.
Clinical Implications
When considering magnesium supplementation:
- For systemic magnesium deficiency: Choose oral supplementation as the first-line approach
- For acute, severe conditions (severe asthma, cardiac arrhythmias): Use intravenous magnesium under medical supervision
- For topical products: Be aware that despite marketing claims, there is minimal evidence that magnesium is absorbed in meaningful amounts through intact skin
Potential Risks
While transdermal magnesium products are unlikely to cause harm when used as directed, patients should be cautioned about:
- False sense of security if using transdermal products instead of proven oral or IV formulations when medically indicated
- Potential skin irritation from concentrated magnesium solutions
- Financial waste on products with unproven efficacy
Despite claims about the superiority of transdermal magnesium, patients requiring magnesium supplementation should be directed toward evidence-based oral supplementation or, when medically indicated, intravenous administration under appropriate supervision.