Research conducted by the World Health Organization found that the most common source of counterfeit drugs is India and China.
The most commonly counterfeited drugs are genitourinary medicines, anti-infective drugs, and central nervous system drugs.
Up to 10 percent of the drugs on sale in developing countries are may be counterfeits.
Source: Olga Khazan, “Here’s why 10 percent of the developing world’s drugs are fake,” Washington Post, November 14, 2012.