What is a common effect of antihistamine medications?

Antihistamine medications are commonly known for their sedative effects, which is primarily because they block the action of histamine in the body, a neurotransmitter involved in wakefulness. By inhibiting histamine's role in the central nervous system, these medications often lead to increased drowsiness. This property is frequently utilized in over-the-counter sleep aids and some cold and allergy medications, as it can help alleviate symptoms like itching or runny nose while also providing a calming, sleep-inducing effect.

While other options may relate to the effects of different classes of medications, they do not accurately describe the common outcome of antihistamines. For example, increased appetite is not a typical or prominent side effect of antihistamines; similarly, insomnia would generally not be associated with these drugs as they promote sleepiness instead. Excitation is contrary to the primary sedative effect produced by antihistamines. Thus, drowsiness stands out as the hallmark impact patients might experience while using antihistamine medications.