I am not a doctor. Consult your doctor. That said, my non-medical grain-of-salt advice.
Find out the mechanism of action.
1) If the allergy medicine is "anticholinergic" -- same mechanism of action but not the same drug -- then it may or may not have the same side effects.
2) If it is "diphenhydramine" then it likely does have the same side effects (even if different delivery).
3) If it is a different mechanism of action then it likely will not have the same side effect.
If 1 monitor the research, if 3 you probably don't need to worry at all. If 2: talk to your doctor about alternatives. Keep in mind this is just a single study and new evidence may overturn current evidence. But the side significance and magnitude of the effect I would say is cause for concern (again just one study I expect there will be many more).
Presumably one takes it by an inhaler so that it goes directly to the trachea/lungs/etc instead of having to get absorbed through digestion, get distributed in the bloodstream, survive the liver, and finally make it to the needed areas.
Find out the mechanism of action.
1) If the allergy medicine is "anticholinergic" -- same mechanism of action but not the same drug -- then it may or may not have the same side effects.
2) If it is "diphenhydramine" then it likely does have the same side effects (even if different delivery).
3) If it is a different mechanism of action then it likely will not have the same side effect.
If 1 monitor the research, if 3 you probably don't need to worry at all. If 2: talk to your doctor about alternatives. Keep in mind this is just a single study and new evidence may overturn current evidence. But the side significance and magnitude of the effect I would say is cause for concern (again just one study I expect there will be many more).