Health issues prove mountainous for many people around the world, and the quality and availability of health care varies from culture to culture. In the United States and some other modern industrialized nations, it’s become common for many patients to combine Western medicine with alternative, herbal, and traditional practices and remedies. The problem: Not all combinations prove to be healthy blends.

According to a recent report published by the Journal of the American College of Cardiology, mixing Western pharmaceuticals and herbal treatments can be dangerous for heart patients—who frequently do so without consulting their cardiologists. Although the herbs themselves may be safe, they may be harmful when taken with certain drugs, says Dr. Arshad Jahangir, a consulting cardiologist with the Mayo Clinic in Arizona, who discussed the issue with HealthDay News. And, he added, it’s estimated that more than 30 percent of Americans rely on herbal remedies or unapproved medications.

Part of the problem, Jahangir says, is Americans don’t get the one-on-one communication they once did with their doctors, so they take their usual heart medications, then treat other symptoms themselves. But since herbs can influence the effectiveness of prescription medications, that self-treatment can have severe consequences. Jahangir cites St. John’s wort, a popular herbal remedy for depression and sleep problems. The herb, he says, has a major effect on the liver, which is crucial to the metabolism of drugs prescribed for heart disease and could reduce their effectiveness. And because St. John’s wort is immunosuppressive, it also could create problems for heart transplant recipients.

Tell your physician about any alternative medical and herbal products you use so together you can decide whether the combinations are healing or harmful. The last thing you want from any remedy is to make a difficult health problem even worse.