How Long Does It Take Magnesium Citrate to Work?

Magnesium citrate is a saline laxative that generally produces a bowel movement within 30 minutes to three hours, according to WebMD. While patients sometimes use it for relief of constipation, whenever possible they should choose milder laxatives. Some surgical procedures require preparation using magnesium citrate with other laxatives.

Magnesium citrate works by attracting water to the bowel and retaining it there, according to This increase in volume causes the bowel to evacuate. Patients should take the medication on an empty stomach and with 8 ounces of water to prevent dehydration. Individuals taking other medications should wait at least four hours after taking the medication before using magnesium citrate.

When patients use magnesium citrate too often, WebMD indicates they may develop laxative dependence. Laxative dependant patients cannot have a bowel movement without taking more laxative. Patients who take the medication and do not have a bowel movement could have a serious medical condition and should contact their doctor.

Most people tolerate magnesium citrate with minor side effects including gas or bloating. However, individuals who use the medication at higher than the recommended rate or for extended periods have a chance of developing serious side effects such as irregular heartbeat, mood changes or bloody stools.