Fed by the insatiable needs of the New-Age must-feel-good self-medicating generation, the past decade has seen an explosion in the commerce and popularity of alternative therapies and countless over-the-counter supplements and herbal products—a multibillion-dollar industry with little or no control on uniformity and purity. Not classified as "drugs," herbals and supplements fall out of the umbrella of consumer protection. Contamination with herbicides, pesticides, heavy metals, molds and toxins have been reported. The active ingredients may vary from brand to brand—and in some, none at all. Some may contain ingredients with undesirable effects.

A great divide exists between pharmaceutical medicine and alternative medicine—the former often looks at alternative modalities with disdain, while the alternativists reject western therapies for its expense and toxicity—the commerce of alternative medicine has lured many physicians into a merging of prescription medicine with herbals and supplements. Talk-Radio medicine—seemingly informational for medical disease, but often a source of misinformation—often segue to the selling of herbal supplements, with hardly any caution on the possible interactions between herbs and drugs.

The increased commerce and popularity of alternative herbal therapies has brought added concern of unfamiliar herb-drug interactions in the already complicated world of pharmaceutical drug-drug interaction. Adding to the problem, patients are often hesitant to inform their physicians about their use of herbal supplement. Often the patients are themselves grossly uninformed of the side effects of herbal supplements they are using or their possible herb-drug interactions, indulging in it because of the word-of-mouth promise and snake-oil promotions.

Sadly, in time-constrained ka-ching medicine, physicians do not have the time to inquire into patients' alternative medicine use. Even if they do, physicians are usually uninformed, unable to provide the necessary guidance and information to assist patients in maneuvering through the confusing maze of alternative and supplementary therapies and their potential interaction with prescription drugs.

In my unending effort of updating the studies on medicinal plants, I am often filled with wonder on the treasure trove of herbal medicine, the studies that support the folklore of its use, and the its untapped potential. But while many plants—leaves, roots, seeds, and fruits—are wonderful sources of natural antioxidants and constituents that could potentially benefit the prevention and treatment of many medical diseases, there are some that can negatively impact pharmaceutical therapies through herb/drug interactions.

Some herbal therapies and supplements can increase or decrease the effects of anticoagulant (blood thinning) treatment, augment the hypoglycemic effects of antidiabetics and the hypotensive effects of antihypertensive drugs. Fruits can affect blood sugar levels in diabetics, dangerously increase potassium levels in patients with renal disease. Some plants parts—flowers, leaves, seeds, fruits—have reported toxicities, unknown to many users.

This page will focus on information on herb-drug interactions. While some are from human clinical studies and observations, many are from animal studies. The list is, of course, incomplete but updated as new information is gathered from frequent updating on scientific studies for the medicinal plants.

Please click on plant names to go to specific plant page for more detailed information on studies, interactions, and sources.