The New Zyrtec and Xyzal Side Effect: How to Treat It and When to Contact Your Doctor

Allergies are, in fact, getting worse. That would explain why common allergy medications like Zyrtec (cetirizine) and Xyzal (levocetirizine) fly off drugstore shelves every year to treat allergy symptoms like a runny nose, itchy eyes and hives. However, if you take these drugs, there is something you should know: The FDA recently published a warning about a newly discovered side effect that may occur when taking both Zyrtec and Xyzal. 

If you stop taking Zyrtec or Xyzal after long-term use, you might experience rare, but severe, itching. Also called pruritus, this itching was experienced by patients who were taking these allergy medicines every day for several months or years and then stopped taking the medication. 

The FDA estimates that 62.7 million over the counter packages of cetirizine and levocetirizine were bought in 2022. In the same year, about 26.8 million cetirizine and levocetirizine prescriptions for OTC and prescription products were dispensed from US outpatient pharmacies. Considering that allergies are getting worse -- partly because of climate change creating longer, more intense pollen seasons -- it wouldn't be surprising if these numbers continue to climb. 

The FDA decided to issue this warning after identifying 209 cases worldwide -- 180 cases for cetirizine, 27 for levocetirizine and two for both -- of this particular side effect reported between April 2017 and July 2023. In the US, 197 cases were reported. However, there may be more, because these are only those that were reported to the FDA. 

Interestingly, even though most patients who experienced this severe itching had been taking these antihistamines for more than three months, some had this reaction after less than one month of use. 

Because of these findings, the FDA will now include a warning on the prescribing information for prescription cetirizine and levocetirizine. The administration is also asking that manufacturers add this warning to drug facts labels for OTC versions. 

When to contact your doctor

If you stop taking OTC cetirizine or levocetirizine and develop severe itching within a few days after you've been using the medicine daily for several months to years, you should contact your doctor. If you plan to take these medicines for a prolonged period of time, you should also discuss the pros and cons with your doctor before starting.

How to treat this new Zyrtec and Xyzal side effect 

According to the FDA, no effective treatments for pruritus have been found. However, most patients discovered that their symptoms resolved after they restarted cetirizine or levocetirizine or after they tapered off the antihistamine after restarting it. Before you try this, consult your doctor to make sure that's the best course of action if you think you're dealing with this Zyrtec or Xyzal complication.

According to the FDA, the most common, already-known side effects of cetirizine and levocetirizine are fatigue, drowsiness, sore throat, cough, dry mouth, nosebleed, fever, diarrhea and vomiting. 

What is pruritus? Plus, additional symptoms to know

The Cleveland Clinic reports that pruritus is the medical term for "itchiness." It can be painful or irritating and spread to multiple areas of the body. Other symptoms of pruritus can include a rash, blisters, large bumps, small pimple-like bumps and skin discoloration. 

Scratching the skin can cause additional symptoms, such as skin breaks and bleeds, scratch marks, dry or cracked skin, broken skin that leaks a yellow to white fluid (infection), localized pain where the skin itches and a thick, leathery patch. That is why it's important to do what you can to manage your itching under the care of a doctor. 

Dry skin, pregnancy, contact with an allergen and a reaction medication are common causes of pruritus. If it occurs for over six weeks, it can be considered chronic.