Allergic reactions to Acetazolamide are rare. People ascribe many different symptoms of allergies. If you are supposed allergy to sulfa drugs, consults your doctor. Consider taking a test dose of acetazolamide under the controlled clinical situation to determine whether or not have a true allergy. Dexamethosone is not recommended for preventing altitude illness in routine situations. Consider it for rescue situations to high or extreme altitude requiring rapid ascent by air transport. Take nifedipine if you have had HAPE before.