I make up my own medical kits rather than using pre-made ones, as then I can customize for the illnesses and accidents I seem most likely to have.
I usually carry two medical kits, one with medicines and drugs, and another that is useful for treating wounds. Drugs tend to be bulky, so I leave this one in my suitcase in my lodging. If you fall sick, you often have time to return to your lodging to get the drugs you need. The first aid kit for wounds, however, I carry on my person, usually in my laptop bag. If you’re in a car accident or you seriously cut or burn yourself, you don’t have time to drive all the way back to your lodging to get your first aid kit. You want to be able to treat yourself (or anyone else) pronto if bleeding is involved. I carry special flat bandages that are thin and not bulky, plus some medical tape, gauze, and a needle and thread for stitches. Sometimes in remote dusty places I carry small disposable vials of saline for cleansing wounds.