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MiraLAX

Generic name: polyethylene glycol 3350pol-ee-ETH-il-een-GLYE-kol ]
Drug class: Laxatives

Medically reviewed by Sanjai Sinha, MD. Last updated on Aug 15, 2023.

What is MiraLAX?

MiraLAX is a laxative solution that increases the amount of water in the intestinal tract to stimulate bowel movements.

MiraLAX is used as a laxative to treat occasional constipation or irregular bowel movements.

MiraLAX may also be used for purposes not listed in this medication guide.

Important information about MiraLAX

You should not use MiraLAX if you have a bowel obstruction or intestinal blockage. If you have any of these conditions, you could have dangerous or life-threatening side effects from MiraLAX.

People with eating disorders (such as anorexia or bulimia) should not use MiraLAX without the advice of a doctor.

Before taking MiraLAX, tell your doctor if you are allergic to any drugs, or if you have ulcerative colitis, irritable bowel syndrome, kidney disease, nausea or vomiting with severe stomach pain, or if you have had a sudden change in bowel habits that has lasted 2 weeks or longer.

MiraLAX should produce a bowel movement within 1 to 3 days of using the medication. Polyethylene glycol 3350 normally causes loose or even watery stools.

Do not use MiraLAX more than once per day. Call your doctor if you are still constipated or irregular after using this medication for 7 days in a row.

Before taking this medicine

You should not use MiraLAX if you are allergic to polyethylene glycol, or if you have a bowel obstruction or intestinal blockage. If you have any of these conditions, you could have dangerous or life-threatening side effects from polyethylene glycol 3350.

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

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

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.

It is not known whether polyethylene glycol 3350 passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How should I take MiraLAX?

Use MiraLAX exactly as directed on the label, or as it has been prescribed by your doctor. Do not use this medicine in larger or smaller amounts or for longer than recommended.

To use MiraLAX powder, measure your dose with the medicine cap on the bottle. This cap should contain dose marks on the inside of it. Pour the powder into 4 to 8 ounces of a cold or hot beverage such as water, juice, soda, coffee, or tea. Stir this mixture and drink it right away. Do not save for later use.

MiraLAX should produce a bowel movement within 1 to 3 days of using the medication. Polyethylene glycol 3350 normally causes loose or even watery stools.

Do not use MiraLAX more than once per day. Call your doctor if you are still constipated or irregular after using this medication for 7 days in a row.

Store at room temperature away from moisture and heat.

Dosing information

Usual Adult Dose of MiraLAX for Constipation:

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

Usual Pediatric Dose for Bowel Preparation:

Occasional constipation:
Children greater than 6 months of age: 0.5 to 1.5 g/kg daily (initial dose 0.5 g/kg; titrate to effect)
Maximum dose: 17 g/day

Fecal impaction:
Children greater than 3 years of age: 1 to 1.5 g/kg daily for 3 days
Maximum dose: 100 g daily

Bowel preparation:
Children greater than 2 years of age: 1.5 g/kg/day
Maximum dose: 100 g daily

Usual Pediatric Dose of MiraLAX for Constipation -- Acute:

Occasional constipation:
Children greater than 6 months of age: 0.5 to 1.5 g/kg daily (initial dose 0.5 g/kg; titrate to effect)
Maximum dose: 17 g/day

Fecal impaction:
Children greater than 3 years of age: 1 to 1.5 g/kg daily for 3 days
Maximum dose: 100 g daily

Bowel preparation:
Children greater than 2 years of age: 1.5 g/kg/day
Maximum dose: 100 g daily

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 make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid?

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

MiraLAX side effects

Get emergency medical help if you have any signs of an allergic reaction to MiraLAX: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop taking this medicine and call your doctor at once if you have:

Common MiraLAX side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect MiraLAX?

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

Popular FAQ

Metamucil and MiraLAX are both brand names for over-the-counter laxatives. This means they help you move feces through your bowels. Metamucil is used to help you have regular bowel movements if you have occasional constipation and you can use it every day. MiraLAX is used to treat occasional constipation. It contains a substance called polyethylene glycol. You should not use it for more than 7 days. Continue reading

For relief of constipation, you can take one dose of MiraLAX at any time of the day for up to 7 days. You may prefer to take it early in the day so that it’s less likely you will have a bowel movement during bedtime or late at night. MiraLAX usually produces a bowel movement in 1 to 3 days. If your constipation worsens or does not improve after one week, contact your healthcare provider. Continue reading

Any drug that is classified as an "opioid" can cause constipation. Examples of commonly prescribed opioids that may cause this side effect include morphine, tramadol, fentanyl, methadone, hydrocodone, codeine and oxycodone. Continue reading

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use MiraLAX only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.