Waiver for medication during race? During the 2017 Tdf, Tim Wellens abandoned during stage 15 due to bad allergies and not being able to breathe.  The commentators said that his team would not "give him a waiver" to take allergy meds.

What exactly is a "waiver for medication"? Why does one need one during a major race and why would Wellens' team not give him one?

I can see how something like pseudoephedrine or a steroid could cause someone to test positive for prohibited substances in a race with strict substance rules and testing.  Is this the entire reason that he was not granted a waiver?

I would think Wellens could/should have taken something benign to help, like a benedryl, in order to continue the race.
There is asthma due to exercise. (Exercise-induced asthma). So one can have lung problem simply due to huge exercise. (not very likely in this case, but possible).

Waiver for meds in my view is "permission" to take a medication. E.g., epilepsy drug to prevent you from having seizure during the race.