The benefits of modern pharmaceuticals are often accompanied by side effects, and although some are minor, like headaches or drowsiness, others can be much more serious.

In this Nature Video, reporter Lorna Stewart asks scientists if we will ever eliminate side effects. Lorna is surprised when Nobel laureate Martin Evans claims there are no side effects, and fellow laureate Oliver Smithies explains how complicated it can be to eliminate the unwanted effects of taking medicine. However, exciting research is on the horizon, as two young researchers explain.