Can using otc peroxide/whitening mouthwash cause dry mouth or "burnt" sensation on tongue? have noticed that in past wk & just started using new rinse

It might: Everyone reacts slightly differently to these products. It may be necessary to use the mouthwash every second or third day if it is irritating the soft tissues. Stop using it for a day or two to give the tissues time to heal.

Yes: your tongue can get very sensitive from whitening products, discontinue temporarily and when symptoms resolve start again, but use less frequently

Definitely, yes: Aside from drying the mouth out, this ingredient is known to cause microscopic damage to the lining of oral tissue that may cause "burnt" sensation of the tongue. Try Biotine - gentle mouthwash that kills germs and prevent dry mouth.