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Compare Lactulose vs. Metamucil

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

Key takeaways

Lactulose (Constulose) and psyllium (Metamucil) are both used to treat constipation, but they work in different ways and have distinct characteristics. Lactulose is a prescription-only osmotic laxative that draws fluid into the gut to soften stools, while psyllium is an over-the-counter fiber laxative that helps stools absorb water, making them bulkier and easier to pass. Lactulose can take up to two days to work and may cause side effects like stomach pain and gas, whereas psyllium can take 12 to 72 hours and may cause bloating, especially when you first start. Lactulose is not suitable for people who are lactose intolerant or on a low-galactose diet, while psyllium must be taken with plenty of liquid to avoid choking. Additionally, lactulose is available as a liquid, whereas psyllium comes in various forms, including flavored powders and capsules.

  • Lactulose (Constulose)
    Psyllium (Metamucil)
  • Lactulose (Constulose)
    Psyllium (Metamucil)

  • Summary of Lactulose vs. Metamucil

    Summary for Osmotic laxative
    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.

    Summary for Fiber laxative

    Psyllium or psyllium husk is an over-the-counter (OTC) fiber supplement. It helps with occasional constipation in adults and children. This fiber laxative most often comes as a powder that's mixed with a beverage. But it can also come in capsules that you swallow. You take this laxative by mouth, up to 3 times a day if needed. Some side effects include gas, nausea, and bloating. Metamucil is a common brand name, but there are other brand-name and generic versions.

  • Indications of Lactulose vs. Metamucil

    Indications for
    •Constipation
    Indications for
    •Occasional constipation

  • Pros and Cons of Lactulose vs. Metamucil

    Pros and Const for Osmotic laxative
    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
    •Not a good option for people who are lactose intolerant
    •Not appropriate for people on a low-galactose diet
    •Not a first-choice laxative because of the side effects
    •Can take up to 2 days for you to have a bowel movement
    Pros and Const for Fiber laxative
    Pros
    •Powder can come in orange flavor with some sugar-free options
    •Also available as capsules, for people who don't like the powder or find it inconvenient
    •Available OTC so you don't need a prescription
    Cons
    •Must take with a lot of liquid so you don't choke on the medication
    •Can take 12 to 72 hours to relieve constipation
    •Can cause bloating, especially when you first start

  • Common Side Effects of Lactulose vs. Metamucil

    Common Side Effects for
    •Passing gas
    •Stomach cramps
    Common Side Effects for
    •Change in bowel habits
    •Bloating

  • Warnings of Lactulose vs. Metamucil

    Common Side Effects for
    •Loss of fluids
    •Possible risk of high blood sugar
    •Problems during colonoscopy
    Common Side Effects for
    •Risk of choking
    •Caution use in people with phenylketonuria (PKU) - flavored powders only

  • Prices with our coupons for Lactulose vs. Metamucil

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    Learn more about Psyllium

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