If you have a sinus infection or heavy congestion, the tubes are already swollen shut, making equalization nearly impossible.
Clearing the Pressure: A Comprehensive Review of Barotrauma and "Blocked Ears" in Aviation blocked ears from flying
Using a spray (like oxymetazoline) about 30 minutes before takeoff and 30 minutes before landing can reduce swelling in the nasal passages. If you have a sinus infection or heavy