Antihistamines are commonly used to treat allergic diseases in children, such as rhinitis, asthma, and urticaria. They are classified into first and second-generation. First-generation antihistamines can cross the blood-brain barrier, causing significant sedation and other side effects, including new-onset seizures, poor academic performance, and paradoxical agitation. Recent studies show an increased risk of seizures, particularly in children aged 6 to 24 months. Although effective, first-generation antihistamines pose serious risks like sedation, cognitive impairment, and increased seizure risk. It is recommended to use newer, nonsedating antihistamines, which have fewer side effects. Children under six years old, especially those under two, should not be given first-generation antihistamines, particularly during flu season.