FlyerTalk Evangelist
Join Date: May 2012
Location: MCO
Programs: AA, B6, DL, EK, EY, QR, SQ, UA, Amex Plat, Marriott Tit, HHonors Gold
Posts: 12,809
Ignoring CV-19 for a moment, even if you have a sinus infection or cold, I would highly recommend you don't fly for your own personal comfort.
I flew with a sinus infection years ago and while going up in altitude was no big deal, coming back down was extremely painful due to my congestion and my ears being unable to equalize. Unfortunately this was a 10+ day business trip and I was miserable the entire time, even after trying numerous decongestants I could not get my ears to equalize. The only relief I got was flying back home and going up in altitude again to a lower pressure, but yet again on arrival the same problem happened. It took about two more weeks for things to finally clear up and return to normal for me after almost a month of pretty nagging discomfort.
If you have a sinus infection/congestion and must fly, take the maximum recommended dosage of a strong decongestant about 20 minutes before you begin descent to help keep things clear to re-equalize. If at all possible though, I'd consider an alternative form of transportation if possible.