Cyproheptadine and atrioventricular block in a patient with congenital heart disease

Cyproheptadine is frequently used for functional gastrointestinal disorders and appetite stimulation, having effects on multiple receptor types, including calcium channels, histamine, and serotonin receptors. In this report, we present a case of variable atrioventricular block in a child with congenital heart disease temporally associated with cyproheptadine use. This case exemplifies the increased risk of adverse drug effects in patients on multiple medications and suggests a relationship between cyproheptadine and heart block. Clinicians should be aware of this potential effect of cyproheptadine when initiating this medication.