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Miralax vs. Constulose

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

Key takeaways

Polyethylene glycol 3350 (Miralax) and lactulose (Constulose, Kristalose) are both osmotic laxatives used to treat constipation, but they have some key differences. Miralax is available over-the-counter, while lactulose requires a prescription. Miralax typically causes a bowel movement within 1 to 3 days, whereas lactulose usually works within 2 days. Both medications can cause side effects like gas and bloating. Additionally, lactulose contains sugars like galactose and lactose, which can affect blood sugar levels, making it less suitable for people with diabetes. Miralax, on the other hand, is generally considered safe for people with kidney problems, provided a healthcare professional approves its use.

Polyethylene glycol

(Miralax)

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Lactulose

(Constulose)

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Summary for Miralax

Over-the-counter

Polyethylene glycol (Miralax) is an over-the-counter (OTC) medication used for occasional constipation. It comes as a powder that you need to mix with a beverage and then drink. Typically, you take a dose of polyethylene glycol (Miralax) once a day, for up to a week. Most people will experience a bowl movement in 1 to 3 days. Some side effects that polyethylene glycol (Miralax) can cause include nausea, bloating, and passing gas.

Indications for Miralax

Pros and Cons for Miralax

Pros

  • Available OTC, so you don't need a prescription from your provider
  • Causes less cramping, bloating, gas, or feelings of "having to go right now" compared to other laxatives
  • A possible option during pregnancy, if provider says it's safe for you to take

Cons

  • Can take a few days before you have a bowel movement
  • Only for short-term relief of constipation
  • Might cause loose, watery stools

Common Side Effects for Miralax

Warnings for Miralax

  • Complete or partial blockage of intestines

Summary for Constulose

Prescription only

Lactulose (Constulose) is a liquid osmotic laxative. It's used to help relieve constipation in adults. This medication is taken by mouth, typically once daily. Once you start treatment, it can take up to two days before you have a bowel movement. Some common side effects of lactulose (Constulose) include stomach pain and passing gas. There's a separate version of lactulose used for symptoms of a liver problem called hepatic encephalopathy.

Indications for Constulose

Pros and Cons for Constulose

Pros

  • Can be used in people with kidney or liver problems
  • Might be a good option for people with constipation who didn’t see benefits with other laxatives
  • Available as a lower-cost generic medication
  • Side effects are mild and typically go away with time

Cons

Common Side Effects for Constulose

  • Passing gas
  • Stomach cramps

Warnings for Constulose

  • Loss of fluids
  • Possible risk of high blood sugar
  • Problems during colonoscopy

Prices with our coupons for Miralax vs. Constulose

Price Card Drug Icon
Polyethylene Glycol 3350 Non-Prescription1 bottle / 30 doses of 17g/dose
$20.53-
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Price Card Drug Icon
Kristalose1 carton / 30 packets of 20g
$107.97$393.69
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Compare other Constipation drugs

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