Dave mentioned that he arrived in Rome “clogged up“. During a recent trip to Southeast Asia, I found the following items essential to long distance, dry air travel (I’ve had allergies over the years):

• Sinucleanse twice daily. Works better, for me, than any of the allergy meds.
• A bottle of nasal saline solution. I used this at least hourly on the long flights and found that it made a big difference.
• I drank a great deal of water (and made sure that I purchased a large bottle at the airport prior to departure). Airlines can sometimes (often?) skimp on water.
• I also carried some aspirin.
• I did not pack all that well for the long dry air, but fortunately found some Hall’s drops in Tokyo

Quantas airlines has a useful page on long distance flight health tips.