Can you tell which one is real and which one is fake? Now imagine your life depends on it.
Developing drugs that target the Plasmodium parasite that causes Malaria is difficult. But what makes matters much worse is that the parasites have shown a remarkable ability to evolve resistance to drugs.
This whole situation is made much worse by the problem of fake drugs which may contain an insufficient amount of active ingredient or none at all.
Natural selection alone can cause diseases to mutate, but resistance is greatly exacerbated by growing numbers of counterfeit and sub-standard drugs, especially in poor countries.
These often contain some correct active ingredients but not enough to cure, just enough to encourage mutation and resistance.
A PLoS paper in 2006, Manslaughter by Fake Artesunate in Asia—Will Africa Be Next? pulled no punches:
We make no apology for the use of the term manslaughter to describe this criminal lethal trade. Indeed, some might call it murder. Somewhere, people are directing a highly technical and sophisticated criminal trade. They are making tablets out of starch, chalk, and a variety of wrong active ingredients, such as erythromycin, for a life-threatening disease that particularly affects the poor and underprivileged. The criminals are making these fakes in the full knowledge that their ineffective product might kill people who would otherwise survive their malaria infection.