A nurse is reinforcing teaching with a client who has a new prescription for digoxin. Which of the following herbal supplements should the nurse include as a contraindication for this medication?

A. Glucosamine. Glucosamine is a supplement used to support joint health, particularly in osteoarthritis. It does not have significant interactions with digoxin and is not known to affect cardiac function or digoxin metabolism, making it safe to use concurrently. B. Garlic. Garlic has blood-thinning properties and may mildly lower blood pressure, but it does not directly interfere with digoxin metabolism. However, clients on anticoagulants or blood pressure medications should use garlic cautiously due to its potential to enhance their effects. C. St. John's wort. St. John’s wort induces liver enzymes that can increase the metabolism of many medications, including digoxin. This can lead to decreased digoxin levels, reducing its effectiveness and increasing the risk of uncontrolled heart failure or atrial fibrillation. Clients taking digoxin should avoid St. John’s wort to maintain therapeutic drug levels. D. Ginkgo biloba. Ginkgo biloba is primarily used to enhance cognitive function and circulation. While it has mild blood-thinning effects, it does not significantly impact digoxin metabolism. However, caution is advised in clients taking anticoagulants or antiplatelet medications to avoid an increased risk of bleeding.