How Do Drugs Work - Non-Sedating Antihistamines

Hello Everyone,

I'm sure it's been a very busy week for everyone and with all the holiday preparations, who has time to be sick. Or, who has time to feel drowsy or stay in bed because they are taking antihistamines for their allergies?

Good News. There are now medications that are called Non-sedating Antihistamines.

Claritin - Loratadine (OTC)
Clarinex - Desloratadine
Zyrtec - Cetirizine
Allegra - Fexofenadine

These are 2nd generation antihistamines that claim to be less sedating than their 1st generation counterparts such as Benadryl - diphenhydramine.

Studies have indicated that these non-sedating antihistamines are as effective as diphenhydramine.

Is there some wordplay going on here?

Are they NON-sedating or are they LESS sedating than their 1st generation counterparts.

Researchers looked at 18 different studies where researchers compared the effects and side effects of the 2nd generation antihistamines and diphendydramine against a non-active ingredient (placebo). When researchers go back and look at studies that have been completed and then summarize the findings of those studies is called a meta-analysis.

In those 18 studies, both the 2nd generation antihistamines and diphenhydramine caused significantly more sedation and psychomotor impairment compared to placebo. However, the diphendydramine caused significantly more sedation and psychomotor impairment than the 2nd generation antihistamines. There were a few exceptions to this trend.

Those studies support the conclusion that the 2nd generation antihistamines are LESS sedating than diphenhydramine. However, they are more sedating than placebo. Therefore, one could conclude that the 2nd generation antihistamines are LESS sedating but they are not NON-sedating.

What does all that mean?

What is really important is HOW DO THEY MAKE YOU FEEL?

CONSIDER - If both diphenhydramine and the 2nd generation antihistamines can control your allergies... does one cause you to doze off and with the other you feel fine?

If that is the case, take the one that works for you. Remember, of the 2nd generation antihistamines, only Claritin in available without a prescription. The 2nd generation antihistamines are also more expensive. Consult with your Pharmacist or Physician for more information.

The 2nd generation antihistamine products are also available in combination with a decongestant, usually pseudoephedrine.

If you have any specific questions regarding your medications, please do not hesitate to email me.

Have a very happy Thanksgiving.

Dr. Paul