Generic name: Psyllium 
Dosage form: powder, capsules, gummies, fibre thins
Drug class: Laxatives

Medically reviewed by Melisa Puckey, BPharm. Last updated on July 24, 2025.

What is Metamucil?

Metamucil contains psyllium, a plant-based fiber, that is used to treat constipation and other digestive health issues. Metamucil may also help lower cholesterol levels, reduce appetite, and benefit blood sugar levels.

Metamucil provides fibre in your diet that absorbs water and swells to form an undigestible gel that helps soften the stool and improve constipation.  The gel may also help reduce cholesterol by trapping bile and cholesterol in the gut, so instead of being reabsorbed, it passes out of the body as waste. Metamucil’s bulking effect can increase the feeling of fullness to help control appetite and slow glucose absorption into the blood. 

Metamucil is available as powder, capsules, gummies, and fibre thins.

Before taking this medicine

Do not take Metamucil if you have an allergy to psyllium or any inactive ingredients in this product.

Ask a doctor or pharmacist if it is safe to use this medicine if you have ever had:

• stomach pain, nausea, or vomiting;
• a sudden change in bowel habits lasting longer than 2 weeks
• difficulty swallowing, bowel blockage, or rectal bleeding.

Tell your doctor if you are pregnant, plan on getting pregnant, or are breastfeeding. You will need to talk about the benefits and risks to you and the baby.

Important information

• Tell all of your healthcare providers that you take Metamucil, including your doctors, nurses, pharmacists, and dentists.
• Do not take Metamucil 2 hours before or 2 hours after taking other oral medicines. This medicine stops many drugs from getting into the body.
• If you have rectal bleeding or you do not have a bowel movement after using this medicine, talk with your doctor.
• Do not use other laxatives or stool softeners unless told to do so by the doctor.
• If you do not take this medicine with lots of liquid, it may swell and block your throat or swallowing tube (esophagus) and may cause choking. Do not take if you have trouble swallowing. If you have chest pain, are throwing up, or have trouble swallowing or breathing after taking this drug, get help right away.
• If you have phenylketonuria (PKU), talk with your doctor. Some products have phenylalanine.

How should I take this medicine?

Use Metamucil as directed by your doctor or healthcare professional. Read all information given to you. Follow all instructions closely.

This product can swell in your throat and cause choking if you don't take it with enough liquid. Drink plenty of fluids each day to help improve bowel regularity.

Always take this medicine with a full glass (at least 8 ounces) of cool or cold water or other liquid.

Powder must be mixed with liquid before you take it. Do not swallow the dry powder. Mix with at least 8 ounces of liquid such as water or fruit juice. Stir and drink this mixture right away. Add a little more water to the glass, swirl gently, and drink right away.

Swallow capsules one at a time and stay in an upright position.

Metamucil usually produces a bowel movement within 12 to 72 hours.

Call your doctor if your symptoms do not improve, or if they get worse.

Psyllium may be only part of a complete program of treatment that also includes diet, exercise, and weight control. Follow your doctor's instructions very closely.

Store at room temperature away from moisture and heat. Keep the container tightly closed when not in use.

What do I do if I miss a dose?

• If you take this medicine regularly, take a missed dose as soon as you think about it.
• If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
• Do not take 2 doses at the same time or extra doses.
• Metamucil may be taken on an as-needed basis. Do not take more often than told by the doctor.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Metamucil side effects

Common Metamucil side effects are bloating, stomach cramps, or a minor change in bowel habits.

Serious side effects

Get emergency medical help if you have signs of an allergic reaction, including hives, difficulty breathing, or swelling of your face, lips, tongue, or throat.

Metamucil may cause other serious side effects. Stop using  this medicine and call your doctor at once if you have:

• constipation that lasts longer than 7 days
• you do not have a bowel movement
• rectal bleeding
• severe stomach pain.

This is not a complete list of side effects, and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Related/similar drugs

How do I store and discard Metamucil?

• Store at room temperature.
• Store in a dry place. Do not store in a bathroom.
• Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
• Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain as it may cause blockages.
• Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

What other drugs will affect this medicine?

Metamucil can make it harder for your body to absorb other medicines that you take by mouth, possibly making them less effective. If you take any oral medicines, take them 2 hours before or 2 hours after you take this medicine.

Other drugs may affect this medicine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Popular FAQ

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer