As a physician, I always travel with meds and recommend the same to my private patients...

Temazepam is my choice for sleep (shorter acting than ambien)
Tamiflu for flu symptoms
Zpak for respiratory infections
Cipro for UTI infections
Excedrin for jet lag (aspirin Tylenol and caffeine)
Benadryl for allergies
Epipen for anaphylaxis
Aspirin for cardiac events
Claritin-D for allergic types
Narcotic for severe pain
Steroid cream, surgical glue, neosporin, gauze, ibuprofen, moleskin for blisters...
Little bit of everything...
If going up in altitude, diamox
And then I customize for specific patients (pediatric, geriatric, asthmatic etc)

But I'm trained to consider all that can go to hell and ruin one's day, vacation (or life).
Happy travels!