Objectives: To investigate the frequency with which sedation was reported in post-marketing surveillance studies of four second generation antihistamines: loratadine, cetirizine, fexofenadine, and acrivastine. Setting: Prescriptions were obtained for each cohort in the immediate post-marketing period.
Subjects: Event data were obtained for a total of 43 363 patients.
The first generation antihistamines have been associated with side effects, particularly sedation.1 Second generation antihistamines are therefore favoured over the first generation drugs, not because of greatly improved efficacy but because they have fewer side effects, especially sedation.24 Although the second generation antihistamines are known to all have similar efficacy,3 the extent of their sedative effects is not well established.
You may have taken antihistamines in the past and found it hard to concentrate or stay awake.
For many people, sedating antihistamines, also called old, classic, or first-generation antihistamines, cause sleepiness, grogginess, and slow reaction time.
Sold over the counter (OTC), they are less expensive than prescription nonsedating antihistamines. Nonsedating antihistamines, also called new, or second-generation antihistamines, are just as effective against nasal allergy symptoms as older medications. They make you less sleepy and groggy, and are less likely to cause problems with increased eye pressure, which may worsen glaucoma symptoms.
Another advantage of the newer antihistamines is that they're available in time-release versions.
They may interfere with coordination and cloud your concentration.
Many sedating antihistamines do not require a doctor's prescription.
For people who need to get to sleep, however, the drowsiness is the main benefit of antihistamines.
These are usually not prescription drugs and can be purchased at retailers over-the-counter.
They can help ease nausea (including in travel sickness) and vertigo, relieve asthma and aid sleep.