Is it possible that crest pro health mouthwash cause an allergic reaction?

Yes: Anything you're exposed to can cause any type of allergic reaction. If you suspect it is the mouthwash then discontinue use to see if things clear up. If not it may be some other thing that is causing this and you may have to see an allergist to be sure. Good luck.

Yes, it may.: Most of those mouthwashes are chemicals that may be irritating to the mucosal membrane, it also depends on each patients sensitivity level and other factors that may combine with the mouthwash to exaggerate the impact. Excessive use of mouthwash may also contribute to hyper-irritation. We have seen incidences of severe local allergic reaction to major brand mouthwashes in our office.

Possibly: Hypersensitivity and tissue sloughing is a more likely outcome than a true allergy.

Unlikely: Are you getting rashes, itching after using it if yes, check with an allergist and stop using.