The short answer? Yes, you can take both Zyrtec and Benadryl. However, when it comes to treating sneezing, coughing, and watery eyes, it’s important to understand the side effects of OTC medications and what's really going on with your body in the first place, says Kara Wada, M.D., assistant professor of allergy and immunology at Ohio State University Wexner Medical Center in Columbus.
So before you go too far down the road of self-treatment, visit a board-certified allergist/immunology doctor to confirm that your symptoms are indeed due to allergies (for a quick take, try our quiz). Then you and your doctor can come up with a comprehensive approach to symptom prevention and management, says Dr. Wada.
Back to the meds at hand: “While you can double up on Zyrtec and Benadryl, there is an increased risk of side effects, especially sedation, when you use both. Plus, taking two medications likely signals the need for better strategies,” Dr. Wada says. Clearly, these two allergy pills aren't doing the trick for you.
Here's how they work: Zyrtec is a long-acting antihistamine that's taken once a day. Benadryl is a short-acting (about 4-to-6 hours max) one that may provide some additional relief. However, Benadryl often causes drowsiness and/or the jitters (yes, opposite reactions), so it's not a great choice if you have to work, drive, or operate machinery.
When patients need additional allergy control, “I tend to recommend using a second long-acting allergy medication in the same class as Zyrtec, such as Claritin and Allegra. They both have a greater potential to last longer and are going to cause fewer side effects than Benadryl," she says.
Dr. Wada suggests taking Zyrtec in the morning without food and a second same-class drug in the evening on especially uncomfortable days when allergy symptoms are flaring. However, she does caution that if someone needs to double up on OTC medications to get relief, it's best to see a doctor. There may be other types of medications that can target your symptoms better.
For instance, a steroid nasal spray such as Flonase, Nasocort, or Rhinocort may be more effective in controlling nasal allergies than an oral medication alone, says Susan Besser, M.D., a family internist at Mercy Medical Center in Baltimore. “For itchy watery eyes, try an eye drop such as Naphcon A or Zaditor,” suggests Dr. Besser.
For severe allergies, shots are an option but they take a few years to work (you have to build immunity), so you'll need symptom relief in the meantime.
Bottom line? When it comes to finding the best allergy medication for your needs, Dr. Wada says it usually requires a fair amount of trial and error. About 1 in 10 people will experience sedation with Zyrtec, so other drugs might be a better fit. What works great for you, may not for your friend. And taking them consistently is key: It can take two-to-four weeks of regular use to see their full effect. And remember: Always consult your doctor before starting a new OTC medication regime.