Note: This document contains side effect information about psyllium. Some dosage forms listed on this page may not apply to the brand name Metamucil.

Applies to psyllium: oral capsule, oral packet, oral powder, oral wafer.

Serious side effects of Metamucil

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Trouble swallowing.

Other side effects of Metamucil

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Stomach pain.
• Bloating.
• Stomach cramps.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

For Healthcare Professionals

Applies to psyllium: oral capsule, oral powder for reconstitution, oral wafer.

Hypersensitivity

Hypersensitivity side effects have been reported rarely. They have included sensitization from inhalation of fine dust particles dispersed into the air as the product is mixed or poured.^[Ref]

While hypersensitivity reactions may be severe, they are most frequently reported by workers in the pharmaceutical firms that manufacture the drug. This is because when it is mixed or poured, fine dust particles are readily dispersed into the air and can then be inhaled and cause sensitization. Orally ingested psyllium seems less likely to induce sensitization.^[Ref]

Gastrointestinal

Gastrointestinal side effects have included several cases of esophageal impaction and duodenal bezoars in patients receiving a bulk laxative product containing 82% psyllium (the active ingredient contained in Metamucil) and 18% senna (commercially available as Perdiem Overnight Relief). Other gastrointestinal side effects have included nausea, intestinal gas, cramps, mild diarrhea, rectal pain, constipation, and irritation.^[Ref]

Hematologic

The case report of eosinophilia was believed to be a sole manifestation of an allergic reaction to psyllium (the active ingredient contained in Metamucil) ^[Ref]

Hematologic side effects have included a case of eosinophilia.^[Ref]