Loratadine versus cetirizine: assessment of somnolence and motivation during the workday

Clin Ther. 2000 May;22(5):573-82. doi: 10.1016/S0149-2918(00)80045-4.


Objective: This parallel-group, double-blind study compared the somnolence and motivation profiles of 2 second-generation antihistamines, loratadine and cetirizine, in patients with allergic rhinitis.

Background: Second-generation antihistamines were developed to provide symptomatic relief from allergic disorders without the unwanted side effects of first-generation antihistamines, including somnolence. Recent research has indicated that not all second-generation antihistamines are comparable with respect to somnolence and other cognitive processes.

Methods: Patients aged > or = 12 years and actively exhibiting symptoms of allergic rhinitis were randomized to 2 treatment groups to receive 10 mg loratadine or 10 mg cetirizine daily at 8:00 AM for 1 week. After patients took the medication, their somnolence and degree of motivation to perform activities were recorded in an electronic diary using a visual analog scale 4 times during the workday (8:00 AM, 10:00 AM, noon, and 3:00 PM).

Results: Sixty patients (31 men, 29 women) were randomized to treatment. Somnolence scores were similar for both groups at baseline and at the time of dosing (8:00 AM). However, there was a statistically significant difference in somnolence scores between the loratadine and cetirizine groups at 10:00 AM (P = 0.008), noon (P = 0.001), and 3:00 PM (P < 0.001), with the cetirizine group showing a greater degree of somnolence. The scores on motivation to perform activities were similar for both groups at the baseline and 8:00-AM measurements. In parallel with the somnolence scores, there were statistically significant differences in motivation scores between the loratadine and cetirizine groups at 10:00 AM (P = 0.014), noon (P = 0.001), and 3:00 PM (P < 0.001), indicating that patients taking loratadine were relatively more motivated during the workday.

Conclusion: The results of this study demonstrate that in patients aged > or = 12 years who had allergic rhinitis, cetirizine use promoted somnolence and decreased motivation to perform activities during the workday compared with loratadine.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Anti-Allergic Agents / adverse effects*
  • Anti-Allergic Agents / therapeutic use
  • Cetirizine / adverse effects*
  • Cetirizine / therapeutic use
  • Disorders of Excessive Somnolence / chemically induced*
  • Double-Blind Method
  • Efficiency / drug effects
  • Female
  • Histamine H1 Antagonists / adverse effects*
  • Histamine H1 Antagonists / therapeutic use
  • Humans
  • Loratadine / adverse effects*
  • Loratadine / therapeutic use
  • Male
  • Motivation
  • Rhinitis, Allergic, Perennial / drug therapy
  • Rhinitis, Allergic, Seasonal / drug therapy
  • Work


  • Anti-Allergic Agents
  • Histamine H1 Antagonists
  • Loratadine
  • Cetirizine