Profound drowsiness is a very common side effect, as is dizziness, difficulty concentrating, and urinary retention.Hydroxyzine is used for allergies and to suppress nausea.However, some feel the trade-off to stop insomnia is worth it.There is also the possibility of drug resistance where the body adapts to the antihistimine and it doesn’t work as well.It is one of the oldest antihistamines available (classified as a first-generation antihistamine), but for many patients surpasses the efficacy of even new prescription drugs.Medical professionals seek out diphenhydramine when a substantial histamine release demands a fast, effective reversal, and is therefore often the drug of choice for allergic rhinitis, motion sickness, insect bites and stings, and hives.
Tylenol PM® also uses an antihistimine to induce drowsiness.
(There are other types of antihistamines that affect H-2, H-3, and H-4 receptors.) People build up tolerance to them over time and when they stop taking them experience rebound insomnia.
Also called histamine antagonists, antihistamines are administered to fight allergic reactions, in which cases sleepiness is considered a possibly undesirable side effect.
The most commonly reported side effects of clemastine use are dizziness, drowsiness, blurred vision, and dry mouth.
Antihistamines are often the first sleep medication insomniacs take, and they are often sufficient. The regulatory authorities have decided they are safe enough that responsible adults can use them unsupervised.