Definitive conclusions on the effectiveness of intravenous magnesium for the treatment of migraine and oral magnesium for migraine prophylaxis, compared with placebo, were not possible. For migraine treatment with magnesium compared with placebo, benefit with respect to pain intensity and need for rescue medication was reported in one systematic review but no benefit was reported in one systematic review. One systematic review on migraine treatment showed that in a subgroup of patients experiencing migraine with aura, there was a benefit with respect to headache relief and headache severity with magnesium compared with placebo. For migraine prophylaxis, one RCT showed that magnesium was more effective than placebo in reducing the number of migraine attacks but there were no statistically significant between group differences with respect to reduction in the number of days with migraine or migraine severity. Evidence for migraine treatment was from three systematic reviews with overlapping studies, and for migraine prophylaxis from one RCT.For complex regional pain syndrome, one RCT found that intravenous magnesium did not result in any benefit over placebo, and one RCT found benefit of intramuscular magnesium, compared with placebo, for pain by some measures but not for others. For refractory chronic low back pain, one RCT showed that intravenous magnesium followed by oral magnesium, was statistically significantly beneficial for pain management compared to placebo. Magnesium was not recommended for the acute treatment of migraine, in one guideline. Magnesium was recommended for migraine prophylaxis, in two guidelines.