NEW YORK, May 27: The US Food and Drug Administration (FDA) has issued a warning regarding a rare but troubling side effect experienced by some individuals who stop taking certain over-the-counter allergy medications such as Zyrtec and Xyzal.

According to the FDA, hundreds of people reported experiencing severe, widespread itching — medically known as pruritus — after discontinuing medications containing cetirizine or levocetirizine, the active ingredients in Zyrtec and Xyzal, respectively. The issue was significant enough in some cases to require medical treatment.

“These reported cases were rare but sometimes serious, with patients experiencing widespread, severe itching that required medical intervention,” the FDA stated in its warning. Some individuals described the itching as so intense that it negatively affected their quality of life and ability to function.

Between 2017 and 2023, the FDA identified approximately 200 cases of post-discontinuation itching. Most of those affected had been using the medications daily for three months or longer, only to develop symptoms after stopping their use.

Cetirizine is sold under several brand names including Zyrtec, Aller-Tec, and All Day Allergy, while levocetirizine is best known as Xyzal. Both are antihistamines commonly used to treat seasonal allergies, and are available in both prescription and non-prescription forms.

In most instances, patients found relief by restarting the medication or by tapering off more gradually rather than stopping abruptly.

While the number of affected individuals is relatively small compared to the tens of millions who use these drugs annually, the FDA is taking action. The agency announced it will revise the labeling of cetirizine and levocetirizine products to include a warning about this potential side effect.

Despite the concern, health officials emphasize that the risk remains low and that these medications are generally safe for most users. However, they encourage individuals to speak with a healthcare provider if they experience unusual symptoms after discontinuing allergy medication.