|Nostril gets blocked|
It's down to what in particular's known as the 'nasal cycle'. We probably won't understand it, however, our bodies purposely direct the wind stream more through one nostril than the other, exchanging between nostrils at regular intervals. A consistent wind stream can dry out the nostrils, which harms their covering, so giving one nostril a rest keeps this from occurring.
At the point when we have a chilly, the veins in the nose widen as a component of the body's insusceptible reaction, and the nose likewise delivers more bodily fluid. Both of these progressions cause blockage, yet you'll feel more impeded in the nostril that is at present 'off the clock'. The nostril with the full wind stream may feel fine.