The best medicine in China is the same as other destinations, in regards to overall prevention. The key to prevention is pacing yourself in consumption terms of food, drink, exercise and awareness of hygiene. Useful items to bring along: general antibiotics such as tetracycline, antacid tablets to be taken before or after meals and insect repellent in the summer (in Southern China). Toilets off the beaten tourist track tend to be primitive so it is useful to bring along your own sanitary necessities and moist towels when venturing outside your hotel.