The Clinical Importance of Herb-Drug Interactions and Toxicological Risks of Plants and Herbal Products

Approximately 70% of the world’s population has been using medicinal herbs as a complementary or alternative medicine that has grown tremendously in both developed and developing countries over the past 20 years (World Health Organization Drugs Strategy 2002–2005). This increase in consumer demand for medicinal plants continues, although scientific data are rare to create safety and efficacy profiles. Its popularity is also related to easy availability, cost-effectiveness leading to better purchasing power, and various factors that perceive that they are generally safe. Herbs are often administered simultaneously with therapeutic drugs for the treatment of major ailments, and herb-drug interactions (HDIs) increase their potential. The main routes proposed for HDIs include cytochrome P450 (CYP450)-mediated inhibition or induction and transport and flow proteins. In our review, we highlighted herbal medicines used for the treatment of various diseases with pharmacokinetic, pharmacodynamic analysis and case reports together with their adverse effects and herb-drug interactions. Therefore, this review can be used as a quick reference database for physicians and healthcare professionals involved in therapy, aiming to maximize clinical outcomes by reducing the negative and toxic effects of plants along with avoiding herb-drug interactions.