Does Zyrtec Cause Weight Gain?

Weight gain is not generally considered a common direct side effect of Zyrtec (cetirizine). Evidence from clinical trials has not established that cetirizine causes weight gain, although individual experiences may vary. Some people report appetite or weight changes while taking antihistamines, but it may be difficult to determine whether the medicine, changes in allergy symptoms, or other factors are responsible. Common side effects of Zyrtec include drowsiness, fatigue, and dry mouth. In adult clinical trials, drowsiness was reported by about 14% of participants taking cetirizine, though rates can vary by dose and population. If you notice unexplained weight changes while taking Zyrtec, other factors like seasonal eating patterns, reduced activity due to allergies, or concurrent medications may be responsible. Track your symptoms and discuss any concerns with your healthcare provider to determine the best allergy management approach for you.