Recurrent aphthous stomatitis (RAS) is an oral condition characterized by frequent attacks of painful oral ulcers. Complex aphthosis (CA) is a severe form of RAS described as the almost constant presence of ≥3 oral ulcers with or without genital aphthosis. Management of primary CA varies, but most patients warrant the use of systemic agents. Because of prolonged treatment, it is preferred to use systemic medications with the least side effects. Herein, we present a case of a primary idiopathic CA. Workup and examination were done to exclude Adamantiades-Behçet's disease and other diseases. The patient was shifted to montelukast after poor tolerance to colchicine. Favorable control of CA was noted during the 5month follow-up period while the patient was on montelukast.