Does taking a antihistamine keep you awake?

Antihistamines can have varying effects on sleep, depending on their specific type. First-generation antihistamines, such as diphenhydramine, are known for their sedative properties and may actually promote sleepiness. In contrast, second-generation antihistamines are less likely to cause drowsiness and are designed to minimize this side effect. Therefore, whether an antihistamine keeps you awake or not largely depends on the specific medication and individual response.