Magnesium citrate, magnesium hydroxide (often sold as “milk of magnesia”), magnesium oxide, and magnesium sulfate (Epsom salt) are the main forms that reliably help you poop because they act as osmotic laxatives and pull water into the intestines. More “gentle” or highly absorbable forms like magnesium glycinate or malate are usually better for general deficiency, sleep, or muscle tension and tend to have much less of a laxative effect.

Best types for constipation

• Magnesium citrate: Common over‑the‑counter option that typically produces a bowel movement within about 30 minutes to 6 hours.

• Magnesium hydroxide: The active ingredient in milk of magnesia; draws water into the bowel and softens stool, often used as a short‑term constipation remedy.

• Magnesium oxide: Poorly absorbed, so more stays in the gut, which can increase water in the stool and improve frequency.

• Magnesium sulfate: Epsom salt taken orally in the correct dose can work as a strong laxative, but it is usually reserved for occasional use and should be used carefully.

Safety tips

• These forms can cause diarrhea, cramping, and dehydration if you take too much, and people with kidney disease or on certain medications need medical guidance before using them.

• For chronic constipation or if you need to use magnesium often, it is important to talk with a clinician to check for underlying issues and to choose the safest dose and form for you.