The objective of this study was to assess the toxicological effects of commonly prescribed pharmaceuticals (Voltaren, Panadol, Selgon, and E.mox) on the microgreen alga Chlorella vulgaris. The algal culture was subjected to various concentrations of the test drugs (0.1, 3.2, 12.8, and 25 mg/L) and incubated for different durations (24, 48, and 96-hrs.). The findings revealed a general decline in algal growth response due to the pharmaceutical drugs, although variations were observed among individual drugs. Both the total carbohydrate and pigment levels exhibited a gradual reduction, displaying a dose- and time-dependent trend. Notably, Chlorella vulgaris treated with the pharmaceuticals at a dose of 25 mg/L exhibited lower total amino acid content compared to the control group. Among the drugs tested, E-mox at a dose of 25 mg/L caused the most significant increase in proline levels. As the drug dosage increased, the activity of three antioxidant enzymes (glutathione reductase, ascorbate peroxidase, and superoxide dismutase) was induced. Electron microscopy analysis of the algal cells grown at a dose of 25 mg/L and incubated for 96 hrs. revealed distinct morphological changes. Panadol treatment resulted in a cell wall surface covered with crowded nipples, while Selgon had no discernible effect on the cell wall. The addition of Voltaren led to a coated surface with dense nipples, whereas E-mox treatment caused irregular cell shapes, loss of distinctive morphology, and wear and fracture of the cell wall. These findings emphasize the importance of controlling such pollutants and implementing monitoring strategies, particularly in water bodies exposed to these pharmaceuticals, to safeguard ecosystem equilibrium and human well-being.