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Metamucil vs. MiraLAX: How do they compare?

Medically reviewed by Carmen Fookes, BPharm. Last updated on Aug 19, 2022.

Official answer


Metamucil and MiraLAX are both brand names for over-the-counter laxatives. This means they help you move feces through your bowels.

They both come as a powder that is dissolved in water for you to drink. However, they work in different ways and are taken for different periods.

  • Metamucil is used to help you have regular bowel movements if you have occasional constipation and you can use it every day. It contains a natural plant fiber called psyllium husk and, in addition to the powdered form, comes as cookies, tablets and gummies. It has a sugar and non-sugar option.
  • MiraLAX is used to treat occasional constipation. It contains a substance called polyethylene glycol. You should not use it for more than 7 days.


Metamucil is a bulk-forming laxative made from a natural plant fiber called psyllium husk. Bulk laxatives are not absorbed in your colon. They absorb water and help you have a soft bulky stool within 12 to 72 hours.

Because this laxative is best used to prevent constipation, you can take it every day. You may start out taking it once per day and increase gradually to 3 times per day if needed. The dose for people ages 12 and over is one rounded teaspoon dissolved in 8 ounces of water. As a fiber supplement, it increases grams of soluble fiber to your diet.

Not taking enough water with Metamucil can cause choking or constipation. Ask your doctor before taking this laxative if you have any trouble swallowing.


MiraLAX is an osmotic laxative. It contains a substance called polyethylene glycol. This substance draws fluid into your colon where stool is formed. The fluid softens stool to help relieve constipation. You should have a watery bowel movement in 1 to 3 days.

The dose of MiraLAX for people over age 17 is 17 grams, which can be measured with the cap on the container. Add the capful to 4 to 8 ounces of water to dissolve and drink. You should not take more than one dose or take MiraLAX for more than 7 days.

Talk to your doctor before using MiraLAX if you have kidney disease or irritable bowel syndrome.


Always let your doctor know if you have:

  • A sudden change in bowel habits
  • Nausea
  • Vomiting
  • Pain
  • Bleeding.

Let your doctor know if you do not have a bowel movement in more than 7 days after taking laxatives. Check with your child’s doctor before giving a laxative to a child.

Constipation prevention

To help prevent constipation, you should eat lots of natural fiber from whole grains, fruits and vegetables and drink plenty of fluids during the day. Regular exercise also helps prevent constipation.

  1. U.S. National Library of Medicine DailyMed. MiraLAX. February 2022. Available at: [Accessed August 19, 2022].
  2. U.S. National Library of Medicine DailyMed. Metamucil. June 14, 2022. Available at: [Accessed August 19, 2022].
  3. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Constipation. May 2018. Available at: [Accessed August 19, 2022].
  4. Procter and Gamble, Metamucil. Metamucil FAQ. Available at:,in%2012%20to%2072%20hours. [Accessed August 19, 2022].
  5. Procter and Gamble, Metamucil. How to Take Psyllium Husk Supplements like Metamucil. Available at: [Accessed August 19, 2022].

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