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psyllium

Generic Metamucil
Used for Constipation

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.

Reviewed by:Last reviewed on December 16, 2025
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What is Psyllium (Metamucil)?

What is Psyllium (Metamucil) used for?

How Psyllium (Metamucil) works

Psyllium (Metamucil) is a bulk-forming fiber laxative. It helps your stool absorb and hold onto water. This makes your stool bigger and softer so it's easier for you to have a bowel movement.

When does Psyllium (Metamucil) start working?Time passed since treatment started:
HOURS
Initial effect
DAYS
Full effect
WEEKS
MONTHS

Drug facts

Common BrandsMetamucil, Konsyl, Reguloid
Drug ClassFiber laxative
Controlled Substance ClassificationNot a controlled medication
Generic StatusLower-cost generic available
AvailabilityOver-the-counter
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Side effects of Psyllium (Metamucil)

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

  • Change in bowel habits
  • Bloating

Less Common Side Effects

  • Gas
  • Nausea
  • Diarrhea

Psyllium (Metamucil) serious side effects

Contact your healthcare provider immediately if you experience any of the following.

  • Choking, trouble swallowing or breathing
  • Rectal bleeding: bright red blood when wiping, red-colored water in the toilet, blood mixed in with or on the outside of your stool
  • No bowel movement after regularly taking the medication
  • Allergic reaction: hives, trouble breathing

Source: DailyMed

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Pros and cons of Psyllium (Metamucil)

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
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Pharmacist tips for Psyllium (Metamucil)

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  • Before taking psyllium (Metamucil), talk to a healthcare professional if you have stomach pain, nausea, vomiting, or trouble swallowing. Also talk to them if you've had sudden changes in your bowel patterns that last for more than 2 weeks. They'll need to check if something else is going on and if this laxative is right for you.
  • Some forms of psyllium contain potassium, sodium, or both. Before taking psyllium (Metamucil), talk to your primary care provider if you need to follow a low-potassium or low-sodium diet. They can make sure this laxative is safe for you.
  • Start with one dose of psyllium (Metamucil) per day. You can slowly go up to three doses per day if needed. This depends on how often you have regular bowel movements.
  • If you're using the psyllium powder: Mix and stir the powder with at least 8 oz (a full glass) of water or other liquid. Then, drink the mixture right away. If it's too thick or gets thick before you can drink it all, you can add more liquid, stir, and drink again. You can also add more water for a lighter flavor or to make it thinner.
  • If you're using the psyllium capsules: Swallow the capsules whole one at a time with a full glass of water.
  • Be sure to drink plenty of water or other liquid when you take psyllium (Metamucil). You should always take it with at least 8 oz (a full glass) of liquid. If you don't drink enough liquid with this laxative, it can thicken and get stuck in your throat. This can lead to choking.
  • Take psyllium (Metamucil) at least 2 hours before or after taking other medications by mouth. This laxative can interfere with how your other medications work.
  • Stop taking psyllium (Metamucil) and talk to your primary care provider if you notice rectal bleeding. Also stop taking it and tell a healthcare professional if your constipation lasts more than 7 days or if you don't have a bowel movement within 3 days of taking the laxative. They can check if something more serious is going on.
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Common questions about Psyllium (Metamucil)

You can take it before bedtime, but be aware that it could lead to some discomfort like gas or bloating. Also you still need to make sure to take it with a full glass of water, so you might need to wake up to go to the bathroom to urinate. If you decide to take psyllium (Metamucil) at night, it's best to take it a few hours before bed so you can get better sleep.

Psyllium (Metamucil) might help with diarrhea for some people. This is because it can help firm liquid stools. But it doesn't work very quickly. Keep in mind that other people might have diarrhea as a side effect of the laxative. See what effect psyllium (Metamucil) has on your stools. Discuss the best treatment options for diarrhea with a healthcare professional.

How much psyllium (Metamucil) you should take per day depends on your age. Carefully read the instructions on your psyllium product (for example, Metamucil brand-name powder). The label should tell you how much is safe for you to take in one day. Ask a healthcare professional if you're not sure how much to take.

When taken over the counter (OTC), psyllium (Metamucil) is used for occasional constipation. You can take psyllium (Metamucil) every day for up to 7 days at a time. If you're still constipated for more than 7 days in a row, stop taking it and ask a healthcare professional. They can see what might be going on and provide guidance on what to do. In general, eating a balanced diet with fiber from fruits and vegetables, drinking plenty of water, and getting daily exercise can all help keep your bowel movements regular.

Some studies suggest that soluble fiber like psyllium can help you feel full and less hungry. This might help control your appetite. But the laxative psyllium (Metamucil) is meant to be taken only for occasional constipation, up to 7 days at a time. It's not clear if you would see much weight change during this time. In general, eating enough fiber every day can help promote weight loss. But you shouldn't take psyllium (Metamucil) every day just to lose weight. If you're worried about your weight, talk to your primary care provider. They can help you make a safe and healthy weight loss plan.

It takes around 12 to 72 hours for psyllium (Metamucil) to help you have a bowel movement. If you don't have one within this time, talk to a healthcare professional.

Some people have felt gassy after taking psyllium (Metamucil). Gas is common after eating a lot of fiber. If this is bothersome, talk to a healthcare professional for alternative options.

Metamucil and Benefiber are two products that contain different kinds of soluble fiber. Metamucil contains psyllium, and Benefiber contains wheat dextrin. Metamucil tends to help the stool hold more water, which can help stool form better. Talk to a healthcare professional to find out which option is best for you.

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Risks and warnings for Psyllium (Metamucil)

Psyllium (Metamucil) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

Risk of choking

  • Risk factors: Not taking with enough liquid | Trouble swallowing

Always take psyllium (Metamucil) with at least 8 oz (a full glass) of water or other liquid. Taking this laxative without enough liquid can cause it to thicken and block your throat. This can cause choking.

If you have trouble swallowing or can't drink a lot of liquid at once, psyllium (Metamucil) might not be a good option for you. Talk to a healthcare professional to find a safer option.

Get medical help right away or call 911 if you have chest pain, vomit, have trouble swallowing or breathing, or start choking after taking psyllium (Metamucil).

Caution use in people with phenylketonuria (PKU) - flavored powders only

Some flavored powder forms of psyllium contain phenylalanine. This is one of the ingredients of the artificial sweetener aspartame. It can cause serious health problems for people with a genetic condition called phenylketonuria (PKU).

If you or your child has PKU, read the psyllium product label carefully to check the ingredients. Talk to a healthcare professional about choosing a safer option.

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Psyllium (Metamucil) dosage

The average cost for 1 can of 368g of 3.4g of Psyllium (Metamucil) is $16.06 with a free GoodRx coupon.
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368g of 3.4g1 can$16.06$16.06

Typical dosage for Psyllium (Metamucil)

Different products can contain different amounts of psyllium husk. Carefully read the directions label on your product to make sure you're taking it properly.

Below are a few examples of psyllium products and their directions for use.

  • Metamucil powder

    • Each packet or rounded tablespoon contains about 3.4 grams of psyllium husk.
    • Adults and children ages 12 or older: The typical dose is 1 packet or 1 rounded tablespoon mixed into at least 8 oz (a full glass) of liquid. Once dissolved, drink the mixture. You can take the medication up to 3 times a day, if needed.
    • Children ages 6 to 11 years: The typical dose is one-half packet or one-half rounded tablespoon mixed into 8 oz of liquid. Once dissolved, have your child drink the mixture. Your child can take the medication up to 3 times a day, if needed.
    • Children younger than 6 years of age: Ask a healthcare professional.
  • Psyllium capsules

    • Each capsule contains about 0.52 grams of psyllium husk.
    • Adults and children ages 12 or older: The typical dose is 5 capsules by mouth with at least 8 oz (a full glass) of water. You can take the medication up to 3 times a day, if needed.
    • Children younger than 12 years of age: Ask a healthcare professional.
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What are alternatives to Psyllium (Metamucil)?

There are a number of medications that your doctor can prescribe in place of Psyllium (Metamucil). Compare a few possible alternatives below.
Psyllium (Metamucil)
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$4.63Lowest GoodRx priceView prices
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  • Occasional constipation
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