Cyproheptadine is an antihistamine medication that blocks h1 receptors to reduce allergic symptoms. It also possesses antiserotonergic activity by antagonizing 5-ht2 receptors. By inhibiting both histamine and serotonin pathways it helps alleviate itching and swelling. The drug is commonly used to treat allergic rhinitis urticaria and certain cases of migraine. Its antagonism of central serotonergic receptors contributes to appetite stimulation and weight gain. The combined receptor blockade produces a protective effect against mediator mediated inflammation.

Cyproheptadine is an oral antihistamine that blocks h1 histamine receptors. It also antagonizes serotonin receptors that influence central nervous system activity. This dual blockade reduces histamine-mediated allergic symptoms such as itching and swelling. The receptor antagonism provides its primary therapeutic effect of relieving allergic conditions. The serotonin receptor effect contributes to its secondary actions in migraine prevention and appetite stimulation. Overall the drug works by modulating allergic and serotonergic pathways to produce its clinical benefits.

Cyproheptadine may cause drowsiness or fatigue in some individuals. Dry mouth and mild gastrointestinal discomfort are also reported. Some users experience dizziness or lightheadedness especially after the first few doses. Blurred vision and mild headaches can occur but are usually transient. An increase in appetite and occasional weight gain have been observed in certain patients. These effects are generally mild and tend to diminish with continued treatment.

Cyproheptadine may cause drowsiness in some patients. It can lead to dryness of the mouth. Weight gain is reported by a minority of users. Allergic skin reactions such as rash may occur. Some individuals experience dizziness or lightheadedness. Gastrointestinal discomfort including nausea has been observed. Swelling of the extremities is a less common but possible effect.