The Dietary Supplement Health and Education Act of 1994 reclassified herbal medications as dietary supplements, thereby exempting them from the stringent safety and efficacy requirements that prescription and over-the-counter drugs are subjected to, such as conducting preclinical animal studies, premarketing controlled clinical trials, or engaging in post-marketing surveillance. As a result of this legislation, the burden falls on the Food and Drug Administration (FDA) to demonstrate a product's unsafety before it can be withdrawn from the market.
Variability in the potency and standardization of herbal medications is common, differing significantly between manufacturers and even among different batches produced by the same manufacturer. This inconsistency, coupled with a lack of regulatory oversight, raises concerns about the safety of herbal medicines. It can lead to issues such as misidentification, substitution with cheaper or more readily available alternatives, contamination with heavy metals or pesticides, adulteration, and the addition of conventional drugs. Despite these risks, the frequency and severity of adverse events related to herbal medicines remain underreported, owing to the absence of compulsory post-marketing surveillance and the challenges in tracking the adverse effects of combining or the synergistic actions of different compounds (Ang-Lee et al., 2001).
