If you have surgery scheduled soon, you may need to set aside your over-the-counter dietary supplements for a while.

Some supplements can interact with drugs given before, during or after orthopaedic surgery, according to a review of studies in the Journal of the American Academy of Orthopaedic Surgeons.

“The main problem with using [supplements] is their interaction with anticoagulants used around the time of surgery,” according to study author David T. Rispler, MD, director of the Grand Rapids/Michigan State Orthopedic Surgery Residency. Many supplements can interfere with anticoagulants, such as warfarin, brand name Coumadin, which are used to reduce the risk of blood clots. That can lead to a greater risk of infection and the need for additional surgery, he says.

Dr. Rispler generally recommends that patients stop taking supplements at least two weeks before surgery, and resume use only after they have finished their course of anticoagulant medication.

“Patients should discuss [with their doctor] their use of all medications, including herbal and over-the-counter remedies, prior to undergoing surgery to decide when is the best time to discontinue and restart them,” Dr. Rispler says.

Supplements known to interact with anticoagulants include: