You are flying home for a wedding and the person in the seat next to you has a super-sloppy sneezy cold. The FAA takes a dim view of your stuffing a passenger into the overhead. The flight attendant will be terribly amused when you ask to be moved to another seat.
Some travel specialists suggest putting a little antibiotic cream in your nose although that won’t defend you from a viral ambush. Vaseline in your nose, however, will help keep you hydrated for the journey and hydration is crucial! Dried out nose, sinuses, eyes and throat cripple your glorious glistening pulmonary mucus blanket that is designed to trap and repel dangerous incoming stuff. Once this protective layer dries out, you are a sitting dried-out duck.
Drink lots and lots of water the day before the trip and lots and lots of water on the plane. LOTS. Notice I did not say coffee, soda, or alcohol, all of which dry you out. Take along eye drops and hand-sanitizer gel that comply with carry-on restrictions. You could wear a tight-fitting mask and tell everyone you are protecting everyone else from YOUR cold. Not very practical but then if you are to be the maid-of-honor . . . . .
You need to be up and moving whenever the aisle is clear to keep your legs free of possible clots anyway and with Typhoid Mary shoulder to shoulder, it is even more important.
And finally, DO NOT SLEEP ON THE PLANE. This is dangerous for your legs and very dangerous for your respiratory system. You will mouth-breathe and you can’t afford it.
Be well. Breathe beautifully.