Given the sensitivity of pharmaceutical products and their direct impact on public health, the liability of manufacturers producing substandard drugs holds particular importance in various legal systems, including Shi'a jurisprudence and Iranian law. This study analyzes the jurisprudential and legal dimensions of civil liability arising from the production and distribution of substandard drugs. Using a descriptive-analytical method and by examining jurisprudential sources and statutory provisions, the research demonstrates that despite the absence of specific legislation in Iranian law, manufacturers can be held liable based on principles such as causation (tasbib), failure to deliver conforming goods, breach of safety guarantees, and the lack of economic value of the product. Furthermore, according to the jurisprudential rule 'He who benefits must also bear the loss' (man lahu al-ghunm fa-'alayhi al-ghurm), the enjoyment of profit entails the acceptance of liability. As a result, strict liability can be established, and the consumer is only required to prove the causal link between the drug and the harm suffered.