Doctors / Backpackers – what medical supplies for international backpackers?

Can anyone tell me what different items I need in my kit of medical supplies for the trip to Japan, India and North / South America. I know that I need things as clean syringes to any other suggestions?

Ibuprofen, the Immodium, antiseptic cream and insect repellent. This should be Case well! Enjoy your trip, you lucky you all!