Postmarket surveillance, particularly adverse reactions (ARs), forms an integral part of the ongoing safety evaluation for natural health products (NHPs). ARs can be related to many factors, including inherent toxicity, misuse, hypersensitivity, NHP-drug interactions, or product quality. High consumer use and limited safety and efficacy data from human clinical trials for many NHPs present a challenge to consumers, healthcare practitioners, and federal regulators. Canada's Natural Health Products Regulations mandate NHPs to be licensed. As the currently available unauthorized NHPs are being brought into compliance in Canada, the transition has produced some challenges, requiring ongoing public communication and education to promote the safe use of NHPs. This article will highlight Health Canada's key postmarket initiatives in strengthening the regulation of NHPs.