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Possible Drug Interactions With Fiber Supplements

When taken at the same time as medications, fiber supplements can affect the absorption of certain drugs: 

  • Psyllium has the potential to reduce absorption of digoxin, Coumadin, lithium, and carbamazepine.
  • Guar gum may slow the absorption of digoxin, acetaminophen, and bumetranide and decrease the absorption of metformin, penicillin, and more. 
  • Pectin may decrease the absorption of lovastatin.

How to Get the Most From Fiber Supplements

These guidelines can help you avoid side effects and interference with drug and nutrient absorption when you take fiber supplements:

  • Check with your doctor before starting a fiber supplement.
  • Gradually increase the amount of fiber you take each day.
  • Drink plenty of liquids -- about 64 ounces daily – to avoid discomfort.
  • Spread fiber intake throughout the day.
  • Take fiber supplements separately from medication; take medications at least one hour before fiber supplements or two hours after fiber supplements.

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Dietary Fiber Poll

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