How to Take MiraLAX

Co-authored by Roy Nattiv, MD and Christopher M. Osborne, PhD

Last Updated: July 3, 2021 References Approved

MiraLAX (polyethylene glycol 3350) is a gentle laxative product that increases the water content in your intestines in order to initiate a bowel movement. It comes in a powder that is easily stirred into hot or cold beverages, and, when taken according to the instructions, is normally effective with minimal side effects. However, special care should be taken with children or those with underlying health conditions.

Method 1

Method 1 of 4:

Drinking an Adult Dose of MiraLAX

1
Open the MiraLAX bottle and look inside the cap. All bottles of MiraLAX come with lids that double as measuring cups. While the outside of the cap is purple, the underside is white up to a line that is marked for 17 grams, which is the proper single dosage for MiraLAX.^{[1]
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- Get a box of single-dose MiraLAX packets so you don’t have to measure it out every time.
- Generic brands of MiraLAX (polyethylene glycol 3350) usually have a measuring cup inside the cap as well, although the particular setup may vary. The standard dose is always 17 grams, though.
2
Fill the cap with MiraLAX up to the marked 17-gram line. Pour the fine, white powder into the cap until it fills the white section of the cap’s underside. Gently tap or shake the cap in order to level out the powder and make sure it’s at the 17-gram line.^{[2]
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- If you have a box of single-use packets, simply pour the contents of a single packet into your chosen beverage (see below).
- Do not take a larger dose of MiraLAX unless instructed by your doctor. Talk to a doctor before giving a child under 17 any amount of MiraLAX.
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3
Pour the MiraLAX into 4–8 fl oz (120–240 ml) of your chosen liquid. MiraLAX can be taken with hot, cold, or room temperature liquids. You need at least 4 fl oz (120 ml) of liquid to fully dissolve a single dose, but you’ll get the best results with a full 8 fl oz (240 ml) glass, which is about the size of a coffee cup.^{[3]
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- MiraLAX is practically flavorless and non-gritty, so it’s fine to take it with plain water. You can also try tea, coffee, or juice.^{[4]
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  Expert Source
  
  Roy Nattiv, MD
  Board Certified Gastroenterologist
  Expert Interview. 18 December 2020.}
- Don’t mix MiraLAX into alcoholic beverages. Also, mixing it into carbonated beverages (like soda) may cause them to bubble over when you stir the mixture.
4
Stir the mixture to dissolve the powder, then drink it all fairly quickly. Use a spoon to give your cup of liquid a quick stir, until you no longer see flecks of MiraLAX in it. Drink the entire cup or glass within the next 10-15 minutes.^{[5]
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- It is not recommended to combine the mixture and then drink some or all of it later since it will thicken and be hard to drink. Wait until you can drink the full amount before mixing it.
- You don’t have to “chug” the mixture, though. Just take normal sips over several minutes until you drink it all. Make sure to stir your glass in between sips so the MiraLAX doesn’t settle on the bottom.
5
Use MiraLAX once a day for up to 7 consecutive days. MiraLAX is formulated and labeled for use no more than once per day. You don’t have to take it at the same time every day, but you shouldn’t take more than 1 dose per day without the approval of your doctor.^{[6]
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- You should also not take MiraLAX for more than 7 days in a row without consulting your doctor. If you’ve taken it every day for a week, stop there until you are able to speak to your doctor.
- Once you achieve regular, soft stools, you can stop taking MiraLAX until the next time you need it.^{[7]
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  Expert Source
  
  Roy Nattiv, MD
  Board Certified Gastroenterologist
  Expert Interview. 18 December 2020.}

Method 2

Method 2 of 4:

Taking Safety Precautions with MiraLAX

1
Check your allergies or medical conditions before taking MiraLAX. You definitely shouldn’t take MiraLAX if you’re allergic to polyethylene glycol, which is the main active ingredient in the product. Also make sure to consult with your doctor if you have any chronic or serious medical conditions, especially the following:^{[8]
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- Ulcerative colitis
- Irritable bowel syndrome
- Kidney disease
- An eating disorder (such as anorexia or bulimia)
- A bowel obstruction or intestinal blockage
- Pregnancy, potential pregnancy, or breastfeeding
- Nausea, vomiting, severe abdominal pain, or a major change in bowel habits that’s lasted for more than 2 weeks
2
Talk to your doctor beforehand about potential drug incompatibilities. MiraLAX typically does not have any significant incompatibilities with other medications. However, it can cause mild to moderate interactions, such as dizziness or cramping, with a wide range of common drugs. To be safe, you should always talk to your doctor or pharmacist about all prescription drugs, over-the-counter medications, and supplements you take.^{[9]
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- Potential drug incompatibilities include acetaminophen, aspirin, ibuprofen, melatonin, omeprazole, oxycodone, prednisone, and alprazolam, among many others.
- You can see the full list of 255 potential interactions at https://www.drugs.com/drug-interactions/polyethylene-glycol-3350,MiraLAX.html.
- Keep in mind that most of these potential interactions are minor, so there’s a good chance you’ll still be able to take MiraLAX.
3
Stop taking MiraLAX and call your doctor if you have negative side effects. MiraLAX works well for most people, but a small percentage may experience serious side effects. Quit using the product and contact your doctor right away if you experience any of the following:^{[10]
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- Rectal bleeding
- Worsening nausea, vomiting, or abdominal pain
- Severe diarrhea
- The product fails to produce a bowel movement within 8 hours

Method 3

Method 3 of 4:

Giving MiraLAX to Kids

1
Contact your doctor before giving MiraLAX to kids under 17. MiraLAX is generally safe for kids aged 6 months and older, but it is not labeled for kids under 17. Do not give any amount of MiraLAX to a child who is 16 or younger without talking to their pediatrician.^{[11]
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- It’s important to get the right dosage based on the child’s size and age. Too much MiraLAX may cause very watery stools and possibly dehydration, while too little may not be effective.
2
Clarify the pediatric dosing instructions with your doctor. For a pre-teen or teen, the doctor will probably advise you to give a standard 17-gram dose. For younger kids, they might recommend a half-dose, in which case you’ll need to fill the cap halfway up to the marked line. For reference, the standard dosage rates for children are as follows:^{[12]
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- Kids 6 months and older: 0.5 - 1.5 g per 1 kg (2.2 lb) of body weight.
- Kids 2 years and older: 1.5 g per 1 kg (2.2 lb) of body weight.
- Contact your doctor if you aren’t sure what the correct dose is for your child. Let them know your child’s age and weight when you ask them.
3
Contact the doctor right away if your child experiences side effects. While rare, children may experience the same serious side effects as adults when using MiraLAX. Stop using the product and tell the doctor right away if the child has any of the following:^{[13]
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- Worsening nausea, vomiting, or abdominal pain
- Severe diarrhea
- Rectal bleeding

Method 4

Method 4 of 4:

Using MiraLAX for Colonoscopy Prep

1
Buy a bottle of MiraLAX and 64 fl oz (1.9 L) of a light-colored liquid. Your colon needs to be completely emptied in order for a colonoscopy to be effective, so the doctor doing the procedure will have a dietary and laxative plan for you to follow in the days leading up to the colonoscopy. Follow their specific instructions, but don’t be surprised if they include the following:^{[14]
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- A full, standard size, 238-gram bottle of MiraLAX.
- A 64 fl oz (1.9 L) jug of a clear or light-colored liquid. Sports drinks (like Gatorade) are often recommended because they replace electrolytes lost as your colon is emptied. However, the liquid cannot be red, purple, orange, or any dark color—choose a pale yellow or clear variety.
2
Mix the full bottle of MiraLAX into the full amount of liquid. You’ll usually be advised to add the entire bottle of MiraLAX to the jug of liquid, shake it up to dissolve the MiraLAX, and store it in the fridge. However, follow the specific instructions given by your healthcare provider.^{[15]
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- Don’t mix up the MiraLAX and liquid until directed to do so—often the day before your procedure.
- Refrigeration makes the beverage more palatable, which is important since you’ll be drinking so much of it!
3
Drink the entire bottle of MiraLAX mix over roughly 24 hours. During the day or so leading up to the colonoscopy, you’ll likely be directed to drink 8 fl oz (240 ml) glass every hour, and then every 15 minutes until it is all gone. You will be given a precise schedule to follow, and you should follow it precisely.^{[16]
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- Shake the bottle up well each time you pour a glass.
- Follow the doctor’s instructions exactly as given to you. If you don’t, the colonoscopy may not be successful and you’ll have to repeat the entire process at a later date.

Expert Q&A
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Question

What are the instructions for taking MiraLAX?

Roy Nattiv, MD
Board Certified Gastroenterologist
Dr. Roy Nattiv is a Board-Certified Pediatric Gastroenterologist in Los Angeles, California. With over 20 years of experience he specializes in a broad range of pediatric gastrointestinal and nutritional illnesses such as constipation, diarrhea, reflux, food allergies, poor weight gain, SIBO, IBD, and IBS. He completed his pediatric residency at the Children’s Hospital at Montefiore, Albert Einstein College of Medicine in New York, and his fellowship at the University of California, San Francisco (UCSF). While at UCSF, he was a California Institute of Regenerative Medicine (CIRM) fellowship trainee and was awarded the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) Fellow to Faculty Award in Pediatric IBD Research. Dr. Nattiv received his undergrad degree from the University of California, Berkeley, and his medical degree (MD) from the Sackler School of Medicine in Tel Aviv, Israel.

Roy Nattiv, MD

Board Certified Gastroenterologist

Expert Answer

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Miralax is a powder that's dissolved in water. Typically, one capsule should be diluted in about 4-6 oz. of water, juice, or another liquid—but not soda or carbonated beverages. That ratio stands, so if you take half a capsule, you'd use 2-3 oz. of water.
Question

How long should I take MiraLAX?

Roy Nattiv, MD
Board Certified Gastroenterologist
Dr. Roy Nattiv is a Board-Certified Pediatric Gastroenterologist in Los Angeles, California. With over 20 years of experience he specializes in a broad range of pediatric gastrointestinal and nutritional illnesses such as constipation, diarrhea, reflux, food allergies, poor weight gain, SIBO, IBD, and IBS. He completed his pediatric residency at the Children’s Hospital at Montefiore, Albert Einstein College of Medicine in New York, and his fellowship at the University of California, San Francisco (UCSF). While at UCSF, he was a California Institute of Regenerative Medicine (CIRM) fellowship trainee and was awarded the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) Fellow to Faculty Award in Pediatric IBD Research. Dr. Nattiv received his undergrad degree from the University of California, Berkeley, and his medical degree (MD) from the Sackler School of Medicine in Tel Aviv, Israel.

Roy Nattiv, MD

Board Certified Gastroenterologist

Expert Answer

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Speak with your physician or gastroenterologist to find the regimen that works for you. The dose and duration really depends on each individual and their degree of constipation.

Warnings

Don’t take MiraLAX as an attempt to lose weight since you may have severe side effects, such as rectal bleeding.

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If the MiraLAX doesn’t have an effect within 8 hours, call your doctor to get checked.

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