Initial Posting: 3/10/2018    Last Update: 5/24/2019
Answer: Topical magnesium products such as MagPro, Fibro Flex and BetterYou are often promoted as easy, effective ways to get magnesium and to reduce muscle pain and cramps, improve flexibility, and promote relaxation and sleep. However, there is little reliable clinical evidence showing these products are effective and topical magnesium products may cause skin irritation, itching and rash. (Note: Some companies claim this irritation is a sign of magnesium deficiency, but this is not scientifically supported). For more details, see the Magnesium Creams, Sprays and Oils section of the Magnesium Supplements Review. Be aware that oral magnesium supplements have also not been found to reduce leg cramps in most people, although one particular form of magnesium supplement may decrease the frequency and severity of leg cramps in women who are pregnant (see our Top Picks for magnesium supplements).
Can other supplements help?
Other supplements can be helpful for muscle cramps and pain caused by specific conditions. For example, CoQ10 can reduce statin-related muscle pain and cramps, and taurine has been shown to reduce the number and severity of muscle cramps in people with cirrhosis.
Coconut water is sometimes promoted to prevent muscle cramps because it is a rich source of potassium, a mineral which is essential for proper muscle and nerve function. Potassium deficiency can cause muscle spasms. However, there are no good studies on the effects of coconut water on muscle cramps. Additionally, nighttime muscle cramps and exercise-related muscle cramps do not appear to be related to potassium levels — but be aware that getting too much potassium has actually been reported to cause leg cramps.
To date, topical CBD (cannabidiol) cream has not been found to help with exercise-related muscle pain.