Answer: antihistamine
Explanation:
Antihistamines are the drugs which are used to treat allergies, congestion, sneezing caused by dust, pollen and insect bite.
These are the suitable drugs for inducing sleep and drowsiness. These have powerful sedating features. These are the active ingredients found in counter sleep aids.
Antitussives are the medicines that suppress coughing. These will inhibit coordinating region of the brain.
Antihistamines are the components of antitussives which suppress the functions of the brain and causes drowsiness.
