Abstract : This study aimed to investigate the effects of combining medicinal plants with synthetic drugs to treat chronic diseases such as hypertension in the Fes-Meknes region of Morocco. The study concerned 250 individuals with chronic hypertension. The study included a list of medicinal plants, belonging to 7 botanical families, used in the treatment of hypertension. Data show that 85.2% of patients use these plants in combination with drugs in treatment. The most frequently treated illnesses were cardiovascular disease (21.20%) and 48 % of patients were unaware of potential side effects of the combination. On the other hand, a bibliographic search in electronic databases for the period 2000-2023 concerned the properties of compounds of drugs and medicinal plants. Study of the effects of medicinal plants and drugs combination in the treatment of hypertension revealed that some medicinal plant species accentuate the hypotensive effects, such as Mentha suaveolens Ehrh, Rosmarinus officinalis L, Thymus vulgaris L, Origanum elongatum, Marrubium vulgare, Mentha pulegium L, Origanum majorana L, Coriandrum sativum L. Argania spinosa L, which can synergize with drugs like, amlodipine, captopril, furosemide and verapamil, increasing the risk of hypotension. The combination of ramipril and rosmarinic acid may increase the risk of hypertension. Databases on herbal drug combinations could help determine efficacy and risks, serving as a platform for healthcare professionals, physicians, pharmacists, and patients.