How much can you take Miralax for severe constipation?

Our content is not intended nor recommended as a substitute for medical advice by your doctor. Use for informational purposes only.

The starting dose of MiraLAX for severe constipation is 17 grams of powder in 8 ounces or 240 mL of beverage. You can gradually increase the dose to 34 grams daily if there is no response. Don’t use Miralax more than once daily for severe constipation unless prescribed by your doctor.

In colonoscopy preparation, you can take up to 17 grams of MiraLAX in 240 mL of water every 10 minutes till 2000 mL of fluid is consumed. However, this large dose is not recommended for occasional constipation, even if it is severe.

The response to Miralax typically occurs within one to 4 days. So, you have to wait for the response before increasing the dose. Increasing the dose of MiraLAX without the permission of your doctor can lead to side effects such as:

  • Nausea and even vomiting.
  • Bloating.
  • Abdominal cramps.
  • Upset stomach.
  • Dizziness.
  • Severe constipation may turn into another condition called “Fecal impaction.” The use of oral MiraLAX in fecal impaction is usually not suitable. Learn More about fecal impaction.

Don’t use MiraLAX for more than two weeks without consulting your doctor.

An alternative for severe constipation is a low-dose MiraLAX  (8.5 grams daily instead of 17 or 34 g) with another laxative. (reference)

We prefer a low dose of MiraLAX and a stimulant laxative (Such as Dulcolax). Consult your doctor about the best option for your type of constipation.

Also, Don’t use MiraLAX for more than two weeks unless prescribed by your doctor.

Can you take MiraLAX more than once (2 or 3 times a day)?

The OTC dose of MiraLAX is once daily. A daily dose of 34 gm of MiraLAX is effective and sufficient to respond to severe constipation.

Your doctor may prescribe Miralax twice or three times a day in special cases of severe constipation (usually for a temporary period). But don’t try this by yourself without permission from your doctor.

Using MiraLAX more than once is associated with an increased risk of side effects such as nausea, vomiting, abdominal bloating, and upset stomach.


What is the maximum dose of Miralax per day?

The maximum dose of MiraLAX is 17 gm (one heaping tablespoon) in 220 mL of clear liquid every 10 minutes until 2000 mL of volume is consumed. This dose is used for bowel preparation before colonoscopy. It is generally not recommended for severe constipation.

The maximum dose of Miralax per day for severe constipation is 34 grams once daily. However, This dose was shown to have an increased incidence of adverse effects. Don’t use MiraLAX doses higher than recommended unless prescribed by your doctor.

When should (and shouldn’t) you take MiraLAX for constipation?

MiraLAX is an osmotic laxative that is minimally absorbed from your intestine. It is safe, effective, and generally well tolerated.

Use Miralax for constipation only after a trial of:

  • Increasing your daily fluid intake.
  • Increasing your dietary fiber intake.
  • Taking a bulk-forming fiber laxative such as Psyllium (Metamucil).
  • Taking fiber-rich Prunes or prune juice. Prunes are found to be the same or more effective than Metamucil in some trials. (reference)
  • If the above measures fail to provide you with relief from severe constipation, then MiraLAX will be a reasonable choice.

However, you shouldn’t take Miralax for severe constipation if:

  • You are not responding to a daily dose of 34 gm of MiraLAX for over four days.
  • You suspect fecal impaction. Learn More.
  • You have intolerable side effects such as upset stomach, nausea, or vomiting.

For how long should you take MiraLAX for constipation?

Use Miralax OTC for constipation occasionally. Don’t use MiraLAX daily for more than one or two weeks without medical permission. Miralax is not approved for long-term use in chronic constipation.

Use Miralax as needed to relieve occasional attacks of severe constipation. A bulk-forming fiber laxative such as psyllium (Metamucil) is a reasonable alternative if you need a long-term alternative. Learn more.

Interesting: How long does MiraLax stay in your systems?


What are the other alternatives for Severe constipation?

Sticking to the standard diet and lifestyle modifications would be best to relieve severe constipation. This will help improve your bowel movements without increasing your laxative doses or using a more powerful alternative.

Before your search for more powerful alternatives for severe constipation, you should:

  • Take more fiber from your diet.
  • Take a fiber supplement.
  • Drink more water.
  • Be physically active.
  • Review your list of medications.

Stronger alternatives to discuss with your doctor for severe constipation:

  • A combination of low-dose MiraLAX (8.5 gm per day PLUS a stimulant laxative every other or every third day (such as Dulcolax). (ref).
  • Using suppositories such as Glycerin.
  • Using an enema for severe constipation. Learn more.
  • Working with your doctor to use the newer anti-constipation medications such as Lubiprostone and Prucalopride.

Can you take Metamucil in the morning and Miralax at night?

A combination of Psyllium (Metamucil) in the morning and Polyethylene Glycol (MiraLAX or Macrogol) at night can effectively treat severe constipation. A 2012 study concluded that taking the two laxatives can combine the advantages of fibers and isotonic solutions.

However, taking Metamucil and MiraLAX daily for a long period is not recommended. Polyethylene glycol (MiraLAX or Macrogol) is not approved for long-term use.

You can only use this combination for a week or two. Never exceed two weeks of this combination without permission from your doctor.

You can use Psyllium (Metamucil) alone after two weeks and then use MiraLAX for occasional attacks of severe constipation.

Learn more: Does MiraLax work for stool impaction?