NIPRISAN(®) is a phytomedicine developed from herbal products used in folkloric practice for the management of sickle cell disease (SCD). The effect of NIPRISAN(®) was tested on human cytochrome P4503A4 drug metabolising enzyme to generate clinically significant data for its safe and efficacious use. Inhibitory activity on CYP3A4 was measured with and without the addition of NIPRISAN(®), by testing different concentrations of the product at 37 °C in reactive mixtures with ketoconazole (2.5 μM) as the positive control. Results showed a low IC50 value of 0.06 mg/ml, indicating that metabolic processes of NIPRISAN(®) are likely to inhibit CYP3A4. The result suggests possible herb-drug interaction may occur, with potential implication on common medications that are CYP3A4 substrates. It is, therefore, advocated that concomitant administration of NIPRISAN(®) along with medications that are CYP3A4 substrates should be done with caution so as not to compromise NIPRISAN(®')s established beneficial effect in the management of SCD.