Abstract Cyproheptadine (CYP) is an antihistaminic and anti-serotonin drug used to improve the clinical course of hospitalized patients severely affected by COVID-19 and requiring supplemental oxygen. Thin layer chromatography (TLC)-densitometry method was developed and validated for the estimation of CYP and its impurity, dibenzosuberone and its degradation product: 10, 11-dihydroxy-dibenzosuberone. The toxicity profiles of CYP impurity and degradation product were studied and the in silico data, using pre-ADMET software, proved their toxicity. A developing system of hexane: methanol: ethyl acetate: formic acid: triethylamine (8:1:1:0.05:0.1, by volume) was used with densitometric scanning at 245 nm. International Conference of Harmonization guidelines were obeyed for method validation. The proposed method was applied on CYP pharmaceutical formulation whose results showed no significant difference from results of the reported chromatographic method regarding accuracy and precision. Method’s greenness was evaluated by analytical Eco scale, Green Analytical Procedure Index, and Analytical greenness approach tools. The developed method can be applied for safety check analysis of CYP containing formulations and detection and even quantification of its related toxic components in quality control laboratories at high sensitivity up to 20-fold than the reported chromatographic method.