One thing I had trouble finding in China was first aid supplies. I brought some of my own, but the pharmacy is a confusing place and you can't expect to find the plethora of supplies available at any Longs Drug, Walgreens, or various other stores that are spread across the Western world. Unless you want to make a trip to either Carefour (the Chinese Wal-mart) or track down the occasional Wal-mart; it's much better to come prepared. Based on my own experience both providing medical needs to others and bumming first aid supplies I forgot to bring, here's a good list of stuff you should pack, without burdening your suitcase too much.
Over-the-Counter Drugs
Headache remedies are a must - you won't easily find the brand you prefer in China, so bring Tylenol, Bayer, Advil, or whatever it is that cures your aches and pains.
Diarrhea medicine is something i thankfully never needed, but frequently passed out to others I traveled with. Definitely pack some, or someone (possibly you) will be sorry.
Histamine blockers are useful for unfamiliar pollens and allergens. You may discover allergies you never knew you had while traveling abroad.
Decongestants will be a life saver when you or someone you know succumbs to the polluted air in many parts of China.
First Aid Supplies
Hand sanitizer is a must because you won't find many public restrooms with soap (and the truly public restrooms are best avoided anyway).
Antibacterial ointments and hydrogen peroxide are a good thing to have to keep cuts from getting infected.
A small box of assorted bandages, some cotton bandages, and bandaging tape all come in handy for minor cuts and blisters.
Grooming tools like nail scissors, finger nail clippers, and tweezers all come in handy both for intended purposes and playing nurse.
If you have any prescription medications you are required to take, bring enough for your trip and a little extra so that you don't run out in the event of an emergency. Of course, consult your physician and pharmacist for any specific needs you might have.
