Abstract: Studies have reported abuse of medications used in treating erectile dysfunction and premature ejaculation, with several adults taking far above recommended doses. A variety of negative effects (including exhaustion) have been associated with the use of these drugs. This study therefore assessed the effects of separate administration of sildenafil citrate, tramadol and their combination on Basal Metabolic Rate (BMR) in relation to body weight, T3 and cortisol levels in rats. Twenty male albino Wistar rats weighing 150-180 g were randomly assigned into 4 groups (n = 5) thus: control (0.2 mL normal saline), sildenafil-treated (10 mg kg–1), tramadol-treated (20 mg kg–1) and sildenafil+tramadol-treated (10 and 20 mg kg–1, respectively) groups. The different drugs were administered orally, every 2 days, for 3 weeks, after one week acclimatization period. The body weight and BMR were measured weekly and serum concentrations of T3 and cortisol were measured at the end of 21 days of treatment. Tramadol significantly (p<0.05) reduced mean food intake, compared with control. Sildenafil and sildenafil+tramadol-treated groups had significantly (p<0.001, p<0.05) lower body weight change, compared with control. Sildenafl-treated group had a lower change in BMR, significantly (p<0.05) different from control and sildenafil+tramadol- treated groups. Serum T3 concentration was significantly (p<0.001) increased in tramadol and sildenafil+tramadol-treated groups, compared with control and sildenafil treated groups. Serum cortisol concentration was significantly (p<0.001) reduced in all treated groups, compared with control. Sildenafil citrate decreased body weight, BMR, serum T3 and cortisol concentrations, while tramadol increased BMR and serum T3 concentration, but decreased serum cortisol concentration and body weight. A combination of these drugs seems to act in a pattern similar to tramadol. This probably explains the feeling of exhaustion reported by users of these drugs.