Magnesium is generally considered safe¹  to take while breastfeeding. In fact, it's an essential mineral that plays various roles in the body, including supporting muscle and nerve function, regulating blood pressure and maintaining a healthy immune system.

Breastfeeding may sometimes lead to low magnesium levels due to the demands of lactation. Supplementing with magnesium can help maintain adequate levels and support overall health.

While magnesium supplements are generally safe, it's always a good idea to consult with your healthcare provider before starting any new supplement regimen. 

Additionally, it's worth noting that obtaining magnesium through a well-balanced diet is also beneficial. Foods like leafy green vegetables, whole grains, nuts and seeds are good dietary sources of magnesium.