Pharmaceutical compounds (PCs) are one of the main classes of emerging contaminants, raising concern due to their potential impact on aquatic ecosystems. Among the most widely prescribed PCs worldwide, acyclovir (ACV), carbamazepine (CBZ), diclofenac (DCF), and propranolol (PRP) are frequently detected in marine environments, due to the limited removal efficiency of conventional wastewater treatment plants. Consequently, marine organisms are continuously exposed to PCs residues, yet their ecotoxicological effects remain largely unexplored. In this study, we investigated the acute toxicity of ACV, CBZ, DCF, and PRP on key marine phyto- and zooplankton species, including the microalgae Dunaliella tertiolecta, Phaeodactylum tricornutum, and Skeletonema pseudocostatum, as well as the invertebrates Amphibalanus amphitrite and Paracentrotus lividus. Ecotoxicological responses were assessed over 72h by investigating growth and chlorophyll inhibition, mortality, developmental anomalies and behavioural alterations, following exposure to both environmentally relevant and elevated concentrations of the tested PCs. No ecotoxicological effects were observed at environmentally realistic concentrations. Conversely high concentrations of all four PCs significantly affected both primary producers and consumers. PRP exhibited the highest toxicity, followed by DCF, ACV, and CBZ. An environmental risk assessment, based on observed ecotoxicological responses, highlighted a high risk associated with DCF and PRP exposure, while ACV and CBZ showed a medium risk potential. Overall, these findings reveal that all PCs can affect multiple trophic levels of marine planktonic communities, emphasizing the need to monitor their occurrence and concentrations in marine ecosystems to support strategies for ecosystem and biodiversity conservation.