Does Zyrtec-D Cause Drowsiness?

Hi Gail and thank you for writing to us.

Zyrtec-D is actually a combination medication. It combines two different medications, cetirizine and pseudoephedrine. Let’s look at these individually.

Cetirizine

Cetirizine (or by the brand Zyrtec) is a “second generation” antihistamine. It works by binding to histamine receptors in the body so that histamine can’t bind to them. This helps to reduce the symptoms typically caused by allergies.

Zyrtec-D is generally well tolerated and lasts about 24 hours per dose. It is often advertised as non-drowsy but about 10-15% of adults will experience drowsiness while taking this according to published drug information. Have you ever taken regular cetirizine before? If regular cetirizine makes you drowsy, then Zyrtec-D may be more likely to than other antihistamine-decongestant options.

Pseudoephedrine

Pseudoephedrine is a behind the counter sympathomimetic drug, or a stimulant drug that mimics the sympathetic nervous system.

It helps to clear sinus congestion but at the same time, tends to increase heart rate and blood pressure. Since it is a stimulant, some people will experience a bit of jitteriness when they take the medication. If you have blood pressure or any heart conditions, you should probably check with your physician before you begin taking anything with pseudoephedrine in it.

Will It Make You Drowsy?

Having given a brief description of each of these, you can see they have somewhat opposing side effects...one can make you tired, and the other has a mild stimulant effect.

Overall, drowsiness after Zyrtec-D isn't that common (due to the addition of pseudoephedrine). There is certainly a chance it may cause drowsiness in some people, but it would be less likely than if you were to take Zyrtec on its own. I would recommend taking your first dose at home, just in case it does make you a bit drowsy.

I hope this helps! Feel free to write back to us in the future!