Compare lactulose vs. Miralax

Head-to-head comparisons of medication uses, side effects, ratings, and more.

lactulose

Miralax
(Polyethylene Glycol)

Relieves constipation and gets rid of ammonia in people with liver problems. Generlac (lactulose) relieves constipation and high ammonia levels, but it can take up to 48 hours to work.Helps get things moving. Miralax (Polyethylene Glycol) provides effective relief of constipation without "cramping" your style.
Reviews & ratings
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Have you used Generlac (lactulose)?
Worth itNot sureNot worth it
Reviews for Miralax
75%
+25% better vs. lactulose
54%
+46% better vs. lactulose
10%
+10% better vs. lactulose
226 reviews
Have you used Miralax (Polyethylene Glycol)?
Worth itNot sureNot worth it
Side effects
lactuloseMiralax

The lactulose FDA package insert doesn’t have numbers about how common side effects are.

More about lactulose side effects »

The Miralax FDA package insert doesn’t have numbers about how common side effects are.

More about Miralax side effects »
How it works
lactuloseMiralax
Generlac (lactulose) draws water into the intestines to soften your stool for easier passing. It also helps draw ammonia into your stool for removal from the body.Miralax (Polyethylene Glycol) is an osmotic laxative. It uses osmosis to keep more water in your intestine, which softens your stool and makes it easier to pass.
Type of medication
lactuloseMiralax
Prescription onlyLower-cost generic availableOver-the-counterLower-cost generic available
Available as
lactuloseMiralax
  • Liquid
  • Powder
  • Liquid
Used for
lactuloseMiralax
Risk factors for serious side effects
lactuloseMiralax
  • Taking Generlac (lactulose) for more than 6 months
  • Elderly
  • Taking medications that cause mineral imbalance
  • Not exercising regularly
  • Diabetes
Detailed Generlac (lactulose) risks & warnings »
  • Taking with medications that cause electrolyte imbalance
  • Age 60 or older
  • Women of childbearing age
  • Malignancy
Detailed Miralax (Polyethylene Glycol) risks & warnings »
Pregnancy

Research studies with animals found harmful effects on unborn babies. It hasn’t been properly studied in humans. The benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

Food
lactuloseMiralax
No food related info.
  • Talk to you doctor about eating certain foods and getting more exercise to help prevent your constipation.
Weight
lactuloseMiralax
No weight related info.
  • Doesn't cause as much bloating, cramping or feelings like you "have to go right now" as other medicines to treat constipation.
  • It causes little to no cramping, bloating, gas, or feelings like you "have to go right now" compared to some other medicines to treat constipation.
Upsides and benefits
lactuloseMiralax
  • Generlac (lactulose) is the first-choice treatment for brain conditions caused by high ammonia levels.
  • Can be used if you have severe chronic constipation leading to blockage.
  • Available in generic.
  • Can be taken orally or rectally.
  • Miralax is the most recommended laxative by pharmacists and doctors.
  • Most people felt it was worth the hassle.
  • It's gluten and sugar free.
  • It causes little to no cramping, bloating, gas, or feelings like you "have to go right now" compared to some other medicines to treat constipation.
  • Works differently than other over-the-counter laxatives so it's a great alternative if other medicines haven't worked.
Downsides and risks
lactuloseMiralax
  • Should not be used if you are on a galactose-restricted diet.
  • Does not provide rapid relief of constipation. Talk to your doctor or pharmacist if you need quick relief.
  • Generlac (lactulose) has a very sweet flavor that most people don't like.
  • You have to dissolve Miralax in a beverage and drink it versus taking a pill.
  • It's not for children 16 years or younger.
  • Miralax doesn't work overnight. It can take up to 2-4 days to have a bowel movement.
  • It's not recommended that you take it for more than a week, so it you haven't had any success, you'll need to call your doctor for other laxative options.
Tips from our pharmacists for people taking the medication
lactuloseMiralax
  • Generlac (lactulose) works within 24 to 48 hours to produce a bowel movement.
  • If you are taking this for constipation, it is usually taken once a day.
  • The goal is for you to have 2 to 3 stools a day.
  • You can mix the oral solution in juice, water, or milk for better taste.
  • Generlac (lactulose) can cause you to be dehydrated, so make sure you drink plenty of fluids.
  • Maintaining a healthy diet, regular exercise, and drinking plenty of fluids can help you prevent constipation.
  • Dissolve Miralax powder in 4 to 8 ounces of water, juice or other drink (cold or hot) once a day.
  • Works in about 1 to 3 days. Don't use for more than 1 week.
  • Miralax is available in four different size dose bottles. It also come in pre-measured single-dose packets to make dosing easier or if you travel.
  • Ask your doctor about giving it to anyone younger than 17 years.
  • Doesn't cause as much bloating, cramping or feelings like you "have to go right now" as other medicines to treat constipation.
  • Ask your doctor before you take Miralax if you have nausea or vomiting, irritable bowel syndrome (IBS), kidney disease, or sudden changes in your stool for more than 2 weeks.
  • Stop using Miralax and call your doctor if you have pain, cramping, swelling or bulging in your belly, diarrhea, rectal bleeding or find you need to use for more than 1 week.
  • Talk to you doctor about eating certain foods and getting more exercise to help prevent your constipation.
Learn more
More about lactuloseSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Generlac (lactulose)?
Worth itNot sureNot worth it
More about MiralaxSide effectsReviews & ratingsAlternativesFDA package insert
Have you used Miralax (Polyethylene Glycol)?
Worth itNot sureNot worth it