Magnesium citrate is the magnesium form most commonly used to make you poop. It is a saline laxative that draws water into the stool, which can soften it and help produce a bowel movement. Magnesium hydroxide, sold as Milk of Magnesia, also works as a short-term laxative. Both commonly work within 30 minutes to 6 hours when taken according to the product label.
Magnesium Forms Compared
| Magnesium form | Likely effect on bowel movements | Best use |
|---|---|---|
| Magnesium citrate | Strong, relatively fast laxative effect | Occasional constipation |
| Magnesium hydroxide | Laxative effect, often within 30 minutes to 6 hours | Occasional constipation |
| Magnesium oxide | Can cause loose stools or diarrhea, but is less predictable for constipation relief | Supplementation or short-term laxative use |
| Magnesium glycinate | Usually less likely to cause diarrhea | Magnesium supplementation with fewer digestive effects |
| Magnesium chloride | May cause diarrhea in some people | Supplementation, rather than constipation relief |
Magnesium citrate and magnesium hydroxide are the clearest choices when the goal is constipation relief because both are used as saline laxatives.
Why Does Magnesium Make You Poop?
Unabsorbed magnesium salts keep water in the intestines. That extra water softens stool and can increase bowel movement frequency. Magnesium salts may also stimulate movement through the digestive tract.
Is Magnesium Citrate or Magnesium Hydroxide Better?
Choose magnesium citrate when you want a magnesium product marketed for occasional constipation. Choose magnesium hydroxide when you prefer Milk of Magnesia or another product labeled as a saline laxative.
Both can work quickly. The practical differences are usually the product format, taste, tolerability and label directions. Magnesium citrate is commonly sold as a liquid. Magnesium hydroxide is available as a liquid, chewable tablet or tablet.
Do not compare products only by the number of milligrams printed on the front of the bottle. Different magnesium compounds contain different amounts of elemental magnesium, and laxative products have their own dosing instructions. Follow the label for the specific product instead of trying to match doses between forms.
Which Magnesium Should You Avoid if You Do Not Want Diarrhea?
Magnesium glycinate is generally a better choice for people who want magnesium without a strong laxative effect. Magnesium citrate, magnesium hydroxide and magnesium oxide are more likely to loosen stools. High amounts of magnesium from supplements or medications can cause diarrhea, nausea and abdominal cramping.
Reactions vary, so magnesium glycinate can still cause digestive symptoms in some people.
How to Use Magnesium for Constipation Safely
- Use magnesium laxatives only for occasional constipation, not as a daily long-term bowel routine.
- Follow the package directions and take the product with the recommended amount of liquid.
- Separate magnesium from certain medicines, including some antibiotics and osteoporosis medicines, because magnesium can interfere with absorption. A pharmacist can confirm the correct spacing for your medication.
- Ask a doctor or pharmacist before using magnesium if you have kidney disease, stomach pain, nausea, vomiting, a magnesium-restricted diet or a sudden change in bowel habits.
- Stop and seek medical advice if you have rectal bleeding, severe symptoms or no bowel movement after using the product.