Can allegra cause a metallic taste in your mouth?

It is not reported in studies. It can be the result of gastric reflux which is a common reason for this

Not listed as side effect. #1 cause of metallic taste is bleeding gums from active gum disease. #2 is acid reflux. See both Dentist or Periodontist and also Physician or Gastroenterologist. Allergy Medecine will not cause or create your symptoms or the cause of the symptoms.