The reason I suggested pre-warning the GP was the result many years ago of a visit to the civilian medical practioner at a military base.
I had a streaming cold and there was only one sensible solution and at my early stage of training I knew it was not to fly. The totally out of it doc OTOH decided I was fit to fly and should have some nasal drops in case I got a blockage.
I was duly issued with a bottle and a pipette, the sort that you put in the liquid, press your finger over the end, put your head back and deliver a drop in each nose.
The only problem was I was to fly in an unpressurised aircraft, at 39000 feet, would be wearing gloves and holding chart, pens, board etc and have nowhere to put the bottle, cap, or pipette. As my ears would potentially get blocked in the descent - about 3000 feet per mile - and we had no spare fuel to climb back up again it was a load of
My instructor agreed and I was grounded.