Can psyllium (Metamucil) cause constipation?

From the Guidelines

Psyllium (Metamucil) can potentially worsen constipation, especially if not taken with adequate fluid intake, as stated in the most recent and highest quality study 1. When considering the use of psyllium (Metamucil), it's essential to weigh the potential benefits and risks. While psyllium is commonly used to treat constipation, the latest evidence suggests that it may not be effective in preventing or treating opioid-induced constipation and may even worsen constipation in some cases 1.

Key Considerations

• The most recent study 1 recommends against using supplemental medicinal fiber, such as psyllium, as it is ineffective and may worsen constipation.
• Adequate fluid intake is crucial when taking psyllium (Metamucil) to prevent it from becoming dry and compacted in the digestive tract, potentially worsening constipation.
• The typical recommended dose of psyllium (Metamucil) is 1 tablespoon of powder or 3-4 capsules 1-3 times daily, always with plenty of water.

Recommendations

• If constipation develops, assess for the cause and severity of constipation, and consider using a stimulant laxative or a heaping tablespoon (17 g) of polyethylene glycol with 8 oz of water 2 times daily, along with maintaining adequate fluid intake 1.
• Start with a lower dose of psyllium (Metamucil) and gradually increase to avoid digestive discomfort.
• Ensure adequate hydration when taking psyllium (Metamucil) to prevent worsening constipation.

From the FDA Drug Label

Ask a doctor before use if you have • abdominal pain, nausea or vomiting • a sudden change in bowel habits persisting for 2 weeks The FDA drug label does not answer the question.

From the Research

Psyllium and Constipation

• Psyllium, also known as Metamucil, is a laxative commonly used to treat constipation 2, 3, 4, 5, 6.
• However, if not taken appropriately, psyllium can worsen constipation, as it can cause intestinal obstruction if not enough fluids are consumed 2.
• A case report found that a 21-year-old man developed an incomplete intestinal obstruction after taking psyllium husks without adequate fluids 2.
• Studies have shown that psyllium can be effective in increasing stool output and improving symptoms of constipation, but it is essential to instruct patients to drink plenty of fluids to avoid bowel obstruction 2, 3, 4, 5, 6.

Factors Affecting Psyllium's Efficacy

• The effectiveness of psyllium in treating constipation depends on various factors, including the dose and treatment duration 4.
• A systematic review and meta-analysis found that psyllium doses greater than 10g/day and treatment durations of at least 4 weeks were optimal for improving constipation 4.
• The type of fiber also plays a role, with soluble fibers like psyllium being more effective than insoluble fibers 3, 5.
• Combining psyllium with other laxatives, such as polyethylene glycol (PEG) or senna, may also be beneficial in treating constipation 5, 6.

Potential Risks and Side Effects

• Psyllium can cause intestinal obstruction if not taken with enough fluids 2.
• Flatulence is a common side effect of psyllium supplementation 4.
• High amounts of insoluble vegetable fiber can worsen digestive symptoms like bloating and distension 5.
• It is essential to follow the recommended dosage and instructions for taking psyllium to minimize the risk of adverse effects 2, 3, 4, 5, 6.