Magnesium citrate contains magnesium and citric acid ... But it can take anywhere from 30 minutes to 6 hours for a magnesium laxative to work. Take it when you know you’ll have easy access ...

There are several forms of magnesium used in dietary supplements, including magnesium citrate, which is one of the most common types of magnesium found in multivitamins and magnesium-only products.