Antiallergics Several antagonistic drugs are used to block the action of allergic mediators, or to prevent activation of cells and degranulation processes. These include antihistamines, glucocorticoids, epinephrine , theophylline . Anti-leukotrienes, such as Montelukast , are FDA approved for treatment of allergic diseases.Anti-cholinergics, decongestants, mast cell stabilizers, and other compounds thought to impair eosinophil chemotaxis, are also commonly used.