Antihistamines are classified into two groups – the first-generation (“sedating”) and second-generation (“non-sedating”).Sedating antihistamines cause sedation as they are highly lipid soluble and readily cross the blood brain barrier.Some antihistamines may also be helpful in reducing anxiety, inducing sleep, or at preventing or treating motion sickness.
Often referred to as the nonsedating antihistamines.
They compete with histamine for histamine receptor type 1 (H1) receptor sites in the blood vessels, GI tract, and respiratory tract, which, in turn, inhibits physiologic effects that histamine normally induces at the H1 receptor sites.
If you're shopping for allergy medication, we'll assume your eyes are itchy, your nose is running, and you can't stop sneezing.
But if you can still breathe through your nose, proceed to Step 2.
Ophthalmic symptoms include red, itching, and tearing eyes.
AR can be associated with comorbidities, such as asthma, sinusitis, otitis media, and sleep apnea.
Antihistamines can be further divided into those unlikely to cause drowsiness (non-sedating antihistamines) or those likely to cause drowsiness (sedating antihistamines).
Antihistamines are used in the treatment of allergic reactions, colds, hay fever, hives, and insect bites and stings.
Some do not appear to produce clinically significant sedation at usual doses, while others have a low rate of sedation.
All are efficacious in controlling symptoms of allergic rhinitis (ie, sneezing, rhinorrhea, itching) but do not significantly improve nasal congestion.
Allergies often manifest after several seasonal exposures to the same set of pollens or potential allergens.