intranasal corticosteroids + oral antihistamines + oral leukotriene receptor antagonists + intranasal antihistamines

This is a **combination therapy regimen** consisting of four classes of medications, each with a distinct mechanism of action, used for the treatment of allergic rhinitis and related conditions: - **Intranasal corticosteroids** reduce inflammation in the nasal mucosa by inhibiting multiple types of inflammatory cells and mediators, leading to decreased swelling, mucus production, and nasal symptoms. - **Oral antihistamines** block histamine H1 receptors, preventing the action of histamine, which is a key mediator of allergy symptoms such as itching, sneezing, and runny nose. - **Oral leukotriene receptor antagonists** (such as montelukast) block leukotriene D4 at the cysteinyl leukotriene receptor, reducing bronchoconstriction and inflammation. - **Intranasal antihistamines** work locally in the nasal mucosa to block histamine H1 receptors, providing rapid relief of allergy symptoms. This multidrug regimen may be used in patients with moderate to severe or refractory allergic rhinitis not adequately controlled by monotherapy or dual therapy[1][2][4]. The combination aims to address multiple inflammatory pathways and symptom types, but increases the risk of additive side effects.