From Luggage dot com
Carry-On Baggage: Size and piece-count matters. In general one item may be carried onboard the plane per passenger.
The dimensions vary slightly by carrier (airline) and by aircraft type and layout. However, it is usually permitted to bring onboard an item that is 9â€? x 14â€? x 22â€? (note ALL luggage marked as â€śCarry-Onâ€? at LuggageGuy.com fit this requirement). Some airlines allow bags up to 25â€? in height onboard. Most airlines request that this carry-on bag should weigh less than 40 pounds, when filled.
Additionally, most airlines allow for one additional â€śpersonal itemâ€? to be brought onboard such as a briefcase, purse, diaper bag, outer garments, or a small shoulder bag. This item MUST fit under the seat.
I do think I've read there are special exceptions made for meds.. The 2 item limit INCLUDES a purse, briefcase, etc. Only one item is allowed per person in the overhead.. the second must fit under the seat..
All fellow passengers appreciate those who follow the rules