Don't overlook cough and cold medicines (mucinex is WONDERFUL - feel free to buy store brand generic versions); tooth ache / care meds and some kind of burn treatment ( Amazon offers a surprising array of meds, sutures and a plethora of medical supplies - including WaterJel products for burn victims).
Keep feminine hygiene maxi pads and tampons for trauma dressings. The tampons are good to plug wounds, absorb a lot of blood and have a string for easier removal. The small tampons plug rifle wounds remarkable well, and the large tampons work well for large caliber / shotgun slug wounds.
Don't forget some kind of splints, ace-style wraps and a way to stabilize / immobilize fractures.
Do some 'net searches on holistic / herbal medicines and treatments.
Obtain colloidal silver for external antibiotic applications. Neosporin antibiotic cream ( often sold generically as "triple antibiotic ointment" ), as well as cortisone ointments and gels /ointments for a myriad of problems are very inexpensive and will be worth their weight in gold in any true survival situation.
For tooth aches you will want "oil of cloves."
Many remarkable drugs are over the counter now that their patent has worn off ( think Tagamet/cimetadine). These meds work just as well as the new really expensive, prescription only meds, but you can get them without any hassle.
DO BUY A PDR ( Physician's Desk Reference) in hardback. Well worth the money, it lists all medicines currently available in the US with dosing instructions, side effects and contraindications.
Do include your friends in SHTF discussions, because we all have different skills and working in small teams increases everyone's chance of survival. In my circle of friends, for example, are two cattle ranchers, two pharamcy technicians, three Registered Nurses, two Licensed Practical Nurses, several local Law Enforcement Officers, an agricultural consultant who works for the State as a resource for local farmers, and several people with military skills that will be very handy. We try to coordinate our purchases for supplies so that we don't wind up with a hundred tubes of burn cream and no trauma dressings.
There are so many more tips - some common sense and some specific knowledge related to training - that one can't list them all here.