Can Allegra (fexofenadine) cause weight gain?

Allegra (Fexofenadine) and Weight Gain

Allegra (fexofenadine) does not cause weight gain and has a safety profile similar to placebo. 1

Evidence on Fexofenadine and Weight

• Fexofenadine is a highly specific H1-receptor antagonist with a safety profile comparable to placebo in clinical trials for seasonal allergic rhinitis and chronic idiopathic urticaria 1
• The type and incidence of adverse events with fexofenadine are comparable to placebo, with no reports of weight gain as a side effect 1
• Unlike some other medications that are known to cause weight gain (such as certain antipsychotics, antidepressants, and mood stabilizers), fexofenadine is not included in reviews of medications associated with weight changes 2

Medications Known to Cause Weight Gain

• Weight gain is commonly associated with specific medications rather than entire drug classes, with varying degrees of weight gain potential even within the same class 2
• Antipsychotics (particularly clozapine and olanzapine), certain antidepressants, and mood stabilizers are well-documented to cause significant weight gain 3, 4
• Among antidepressants, paroxetine has the highest risk of weight gain within the SSRI class, while fluoxetine and sertraline are typically associated with initial weight loss followed by weight neutrality with long-term use 5
• Bupropion is the only antidepressant consistently shown to promote weight loss 6
• Beta-blockers, particularly non-selective ones, can promote weight gain by decreasing metabolic rate and affecting energy metabolism 6

Clinical Implications

• When selecting medications for patients concerned about weight gain, it's important to consider the weight gain potential of various agents 4
• Antihistamines like fexofenadine are preferable for allergy treatment in patients concerned about weight gain compared to medications known to cause weight changes 1
• For patients requiring antihistamine therapy who are particularly concerned about weight gain, fexofenadine is a suitable option due to its weight-neutral profile 1

Monitoring Recommendations

• While fexofenadine is not associated with weight gain, patients with multiple medications should still have their weight monitored regularly, as other concurrent medications might contribute to weight changes 2
• If a patient reports unexpected weight gain while taking fexofenadine, consider other medications in their regimen or underlying health conditions as potential causes rather than the antihistamine 4, 2