How Long Does Miralax Last in Your System?

What is Miralax?

MiraLax (polyethylene glycol 3350) is a laxative solution that increases the amount of water in the intestinal tract to stimulate bowel movements.

MiraLax is used as a laxative for treating occasional constipation or irregular bowel movements.

MiraLax can also be used for purposes not listed in this manual.

How Long Does Miralax Last in Your System?

The following table shows how long each type of laxative takes to work. Among the different types, suppositories work faster, from 15 to 30 minutes.

Sometimes this information is expressed as the half-life of a drug or the amount of time it takes for 50% of the drug to leave the system. The amount of time a drug spends in your system may depend on the active substance, the dose administered and the way it leaves the body.

Laxative active ingredients may have different half-lives. For example, the half-life of lactulose is approximately 2 hours while the half-life of bisacodyl is 16 hours. The mass-forming laxatives do not have a half-life, because they are eliminated with the subsequent intestinal movement.

If you are worried about the amount of time a laxative will spend on your system, you should raise these concerns with a doctor or pharmacist.

Important information about MiraLax

You should not use MiraLax if you have an intestinal obstruction or intestinal blockage. If you have any of these conditions, you may have dangerous or life-threatening side effects from MiraLax.

People with eating disorders (such as anorexia or bulimia) should not use MiraLax without consulting a doctor.

Before taking MiraLax, tell your doctor if you are allergic to any medications, or if you have ulcerative colitis, irritable bowel syndrome, kidney disease, nausea or vomiting with severe stomach pain, or if your habits suddenly change intestines that lasted 2 weeks or longer.

MiraLax should produce a bowel movement within 1–3 days using medication. Polyethylene glycol 3350 usually causes loose or even watery stools.

Do not use MiraLax more than once a day. Call your doctor if you are still constipated or irregular after using this drug for 7 consecutive days.

Do not use MiraLax more than once a day. Call your doctor if you are still constipated or irregular after using this drug for 7 consecutive days.

Before taking this medicine

You should not use MiraLax if you are allergic to polyethylene glycol, or if you have an intestinal obstruction or intestinal blockage. If you have any of these conditions, you may have dangerous or life-threatening side effects of polyethylene glycol 3350.

People with eating disorders (such as anorexia or bulimia) should not use this medication without consulting a doctor.

To make sure this medicine is safe for you, tell your doctor if you have:

  • Nausea, vomiting, or severe pain in the stomach;
  • ulcerative colitis;
  • Irritable bowel syndrome;
  • Kidney disease; or
  • If your bowel habits suddenly change for 2 weeks or longer.

FDA pregnancy category C. It is not known whether MiraLax will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

See also: Warnings about pregnancy and breastfeeding (in more detail)

It is not known whether polyethylene glycol 3350 passes into breast milk or may be harmful to a nursing baby. Tell your doctor if you are breastfeeding.

How do I get MiraLax?

Use MiraLax exactly as directed on the label, or as prescribed by your doctor. Do not use this medicine in larger or smaller quantities or for longer than recommended.

To use MiraLax powder, measure your dose with a medicine cap on the bottle. This cap should contain dose labels inside. Pour 4-8 oz powder of cold or hot beverage, such as water, juice, soda, coffee or tea. Stir this mixture and drink immediately. Do not save for later use.

MiraLax should produce a bowel movement within 1–3 days using medication. Polyethylene glycol 3350 usually causes loose or even watery stools.

Do not use MiraLax more than once a day. Call your doctor if you are still constipated or irregular after using this drug for 7 consecutive days.

Store at room temperature away from moisture and heat.

MiraLax Dosing Information

Usual Adult Dose for MiraLax for Constipation:

17 g (diluted in 8 fluid ounces of water, juice, soda, or coffee) orally once a day

A usual pediatric dose for bowel preparation

Sometimes constipation: 
Children older than 6 months: from 0.5 to 1.5 g / kg per day (initial dose of 0.5 g / kg, titration to effect)
Maximum dose: 17 g / day

Fecal lesion: 
Children older than 3 years: from 1 to 1.5 g / kg per day for 3 days
Maximum dose: 100 g per day

Preparation of the intestine: 
Children older than 2 years: 1.5 g / kg / day
Maximum dose: 100 g per day

Usual Pediatric Dose of MiraLax for Constipation – Acute:

Sometimes constipation:
Children older than 6 months: from 0.5 to 1.5 g / kg per day (initial dose of 0.5 g / kg, titration to effect)
Maximum dose: 17 g / day

Fecal lesion:
Children older than 3 years: from 1 to 1.5 g / kg per day for 3 days
Maximum dose: 100 g per day

Preparation of the intestine:
Children older than 2 years: 1.5 g / kg / day
Maximum dose: 100 g per day

See Also: Dosing Information (in more detail)

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to replenish the missed dose.

What should be avoided?

Follow your doctor’s instructions about any restrictions on food, beverages or activity.

MiraLax side effects

Get emergency medical attention if you have signs of an allergic reaction to MiraLax: hives; Labored breathing; Swelling of the face, lips, tongue or throat.

Stop taking this medicine and consult a doctor immediately if you have:

  • Severe or bloody diarrhea;
  • rectal bleeding;
  • Blood in your stools; or
  • Severe and aggravated pain in the stomach.

Common side effects of MiraLax may include:

  • Bloating, gas, indigestion;
  • dizziness; or
  • Excessive perspiration.

This is not a complete list of side effects, and others may occur. Ask your doctor about side effects.

What other drugs will affect MiraLax?

Other drugs can interact with MiraLax, including prescription and over-the-counter medicines, vitamins and herbal products. Tell each of your health care providers about all the medicines you are using now and any medicine you start or stop using.

The bottom line

There are a variety of laxatives available for the treatment of constipation. Some laxatives are better for the short-term treatment of constipation, while others are more ideal for the treatment of long-term or chronic constipation.

You should always consult your doctor if you are not sure which laxative should be used for constipation.

You can also help to avoid becoming constipated by following some of the following suggestions:

Increase fiber intake

Increase the amount of fiber in your diet. The fiber helps improve intestinal function.

Make sure you have enough fruits, vegetables, and whole grains. Here are 22 foods rich in fiber that you should eat.

Stay hydrated

Having enough fluids can help facilitate the passage of bowel movements.

You should aim for 8 glasses of water a day avoiding things like caffeine and alcohol. Here are 16 reasons to drink more water.

Be active

Making sure that you train regularly can help the stool to move more effectively through the intestine. Here are 6 ways to live a more active life.

Do not hold it

If you feel like you have to have a bowel movement, make sure you go as soon as possible. Do not keep it inside

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