Magnesium deficiency is a common cause of muscle cramps, including leg cramps. However, simply taking magnesium will NOT necessarily fix muscle cramps every time, for every person. There are several situations where taking magnesium may be ineffective by itself:
1)Low potassium ("hypokalemia"). Potassium is found in most foods so dietary insufficiency is rare -- however, many diuretics ("water pills") often cause low potassium alongside low magnesium. Magnesium increases potassium absorption, but this may not be sufficient if a medication is causing large potassium loss.
2)High potassium ("hyperkalemia"). This is caused by renal insufficiency, or as a side effect of ACE inhibitors, angiotensin blockers, potassium-sparing diuretics, or mineralcorticoid resistance/deficiency.
3)Soft tissue calcification (not necessarily hypercalcemia). This is triggered by aging and exacerbated by excessive doses of calcium, especially along with Vitamin D, which greatly increases absorption. Excessive calcium is a risk factor for heart attacks and arterial damage, and is best consumed at a moderate level, spread throughout the day. Insufficient Vitamin K and magnesium can also exacerbate calcification.
4)Low sodium. Low salt diets can cause low sodium levels especially when combined with fluid loss, often due to exercise and/or heat exposure.
5)Statin use. Statins, prescribed for high cholesterol, are correlated with muscle cramps in patient reports. It is unclear at this time how statins cause cramps.
6)Beta-2 agonists. These are inhaler medications prescribed for asthma and COPD, which cause cramps very frequently.
7)Low calcium ("hypocalcemia"). Low serum calcium is known to cause cramps, but it only occurs if you have a very restricted or unusual diet, are grossly Vitamin D deficient, have parathyroid problems, and/or have kidney damage/disease.
8)Proton-pump inhibitors. "PPIs" decrease your stomach acid, which may decrease the absorption of all minerals, including magnesium.
If you believe that dietary magnesium deficiency is the factor causing (or exacerbating) your muscle cramps, you can learn more about our unique magnesium product here.