What is a good substitute for Milk of Magnesia?

October 9, 2025 •

4 min read

While Milk of Magnesia is a common saline laxative used for occasional constipation, not everyone responds to it the same way, and some may experience specific side effects. For this reason, it is helpful to understand what is a good substitute for Milk of Magnesia, including both other over-the-counter options and natural alternatives.

Quick Summary

Several over-the-counter laxatives can replace Milk of Magnesia, including osmotic agents like Miralax and magnesium citrate, bulk-forming supplements such as Metamucil, and stool softeners like Colace. Natural alternatives, including increased fiber intake and proper hydration, are also effective options for managing occasional constipation. Always consult a healthcare provider before making a change.

Key Points

Miralax (Polyethylene Glycol) for Gentle Relief: A popular osmotic laxative that draws water into the colon, providing gentle, longer-acting relief over one to three days with fewer side effects like gas and bloating.
Magnesium Citrate for Faster Action: A more potent osmotic alternative that works faster than Milk of Magnesia, typically within 30 minutes to 6 hours, but requires caution for those with kidney problems.
Fiber Supplements for Prevention: Bulk-forming laxatives like Metamucil (psyllium) and Citrucel (methylcellulose) help prevent constipation by adding bulk to the stool, and are a good option for regular use with sufficient water intake.
Stool Softeners to Prevent Straining: Medications like Colace (docusate sodium) make stool softer by adding moisture, which is ideal for those who need to avoid straining, but they are not fast-acting.
Natural Remedies as a First Step: Lifestyle changes, including a high-fiber diet, adequate hydration, and regular exercise, can be effective natural ways to manage and prevent occasional constipation.
Stimulant Laxatives for Short-Term Use: Products like Dulcolax (bisacodyl) and Senokot (senna) are powerful stimulants for severe constipation but should not be used long-term due to risk of dependency.
Consult a Doctor Before Switching: Always consult with a healthcare provider before changing laxatives, especially for chronic constipation or if you have underlying health conditions like kidney disease.

For individuals seeking an alternative to Milk of Magnesia for occasional constipation, a variety of options are available, each with a different mechanism of action, speed, and side effect profile. Whether due to preference for a different method of relief, concerns about potential side effects like cramping, or simply seeking a more gentle option, understanding the landscape of laxatives is important. Alternatives can be categorized into over-the-counter medications and lifestyle changes.

Over-the-Counter Laxative Substitutes

Over-the-counter (OTC) laxatives fall into several categories, each working differently to promote a bowel movement.

Osmotic Laxatives

This class of laxatives works similarly to Milk of Magnesia by drawing water into the colon to soften stool and facilitate its passage.

Polyethylene Glycol (PEG 3350): Sold under brand names like MiraLAX, this osmotic laxative is often recommended for occasional constipation and is known for being gentler on the system. It works by increasing the water in the intestines and typically takes one to three days to produce a bowel movement, with less gas and bloating than some other options.
Magnesium Citrate: Also a saline laxative, magnesium citrate (e.g., Citroma) is another effective alternative to Milk of Magnesia. It tends to act faster, often within 30 minutes to 6 hours, and is available in a liquid form. Due to its potency, it should be used with caution, especially by individuals with kidney problems.

Bulk-Forming Laxatives

Considered one of the gentlest types of laxatives, bulk-forming agents work by absorbing water in the gut to form a soft, bulky stool. They typically require plenty of fluids to work effectively and can take one to three days to show results.

Psyllium Husk (e.g., Metamucil): A fiber supplement that adds significant bulk to stool.
Methylcellulose (e.g., Citrucel): A plant-based fiber that absorbs water and is less likely to cause intestinal gas compared to other fiber laxatives.

Stool Softeners

Instead of stimulating bowel movements, stool softeners increase the amount of water absorbed into the stool, making it softer and easier to pass.

Docusate Sodium (e.g., Colace): This emollient laxative is a common and safe choice, especially for short-term use. It is not a quick fix, often producing a bowel movement in one to three days.

Stimulant Laxatives

These laxatives work by triggering rhythmic contractions of the intestinal muscles to eliminate stool. Due to their potent effect, they are generally not recommended for long-term use.

Bisacodyl (e.g., Dulcolax): A stimulant laxative that can produce a bowel movement within 6 to 12 hours.
Senna (e.g., Senokot): Another type of stimulant laxative derived from a plant that promotes bowel movements.

Natural and Lifestyle Alternatives

For those who prefer a more natural approach or want to prevent future constipation, certain dietary and lifestyle adjustments can be highly effective.

Increase Fiber Intake: Eating more fruits, vegetables, whole grains, and legumes adds bulk and moisture to stool. Examples include apples, pears, broccoli, and lentils.
Stay Hydrated: Drinking plenty of water is crucial, as dehydration can contribute to hard, dry stools.
Prunes and Prune Juice: These are known for their natural laxative effects due to both their fiber content and a sugar alcohol called sorbitol.
Regular Exercise: Regular physical activity helps stimulate muscle contractions in the intestines, aiding in digestion.
Probiotics: Some individuals find that probiotics, found in foods like yogurt or supplements, can help balance gut bacteria and improve regularity.

Comparison of Laxative Alternatives

To help you decide on the best option, here is a comparison of some popular alternatives to Milk of Magnesia:


Alternative	Mechanism of Action	Time to Effect	Best for...	Considerations
Milk of Magnesia	Osmotic (Saline)	30 minutes to 6 hours	Quick, occasional relief	Caution with kidney issues. Can cause cramping.
Magnesium Citrate	Osmotic (Saline)	30 minutes to 3 hours	Faster-acting relief	Stronger, can cause nausea and stomach pain. Not for those with kidney issues or electrolyte imbalances.
Miralax	Osmotic	1 to 3 days	Gentle, regular relief	Less gas and bloating than some fiber supplements.
Fiber Supplements	Bulk-forming	1 to 3 days	Long-term prevention	Must be taken with plenty of water to prevent blockage.
Stool Softeners	Emollient	1 to 3 days	Preventing straining	Often recommended post-surgery or for hemorrhoids.
Stimulants	Trigger contractions	6 to 12 hours	Severe, acute constipation	Not for long-term use; risk of dependency.

Conclusion

Choosing a suitable alternative for Milk of Magnesia depends on your specific needs, the speed of relief required, and any underlying health conditions. For a gentler, slower-acting option, Miralax or a bulk-forming fiber supplement like Metamucil are excellent choices. For a faster, but more potent, effect, magnesium citrate may be considered with caution. Natural approaches such as increasing fiber and hydration should be the first line of defense for preventing occasional constipation. Before trying a new laxative or for chronic issues, it is always best to consult with a healthcare professional to determine the safest and most effective solution for your situation. For further reading on constipation diagnosis and treatment, the Mayo Clinic provides authoritative guidance.

Mayo Clinic - Constipation: Diagnosis and treatment

Frequently Asked Questions

Magnesium citrate is a fast-acting saline laxative that typically works faster than Milk of Magnesia, often producing a bowel movement within 30 minutes to 3 hours.

Yes, Miralax is a very common and effective osmotic laxative substitute for Milk of Magnesia, offering a gentler alternative with less gas and bloating, though it takes longer to work (1–3 days).

Yes, natural alternatives include increasing dietary fiber from fruits and vegetables, drinking plenty of water, and consuming prunes or prune juice, which are known for their natural laxative properties.

Individuals with kidney problems should use magnesium-based laxatives like Milk of Magnesia and magnesium citrate with caution. Miralax or bulk-forming laxatives are often safer alternatives, but a healthcare provider should be consulted for proper guidance.

Yes, a stool softener like docusate sodium (Colace) is a different type of laxative that adds moisture to the stool, making it easier to pass. It works more slowly than Milk of Magnesia but can be effective for preventing straining.

Miralax is generally considered to be a gentler option than Milk of Magnesia. It works more slowly and is less likely to cause the cramping, urgency, and diarrhea often associated with faster-acting saline laxatives.

Stimulant laxatives, such as Dulcolax or Senokot, can provide powerful relief but are not recommended for routine or long-term use. They can cause dependency and are best reserved for severe, occasional constipation.