What's the Science of Painkillers?

When you've got a headache, those bottles of over-the-counter medicines can feel interchangeable. But the truth is, the drugs work in different ways... and each has their own benefits and side-effects. From which drugs work best on toothaches, to which ones are best for hangovers, Will and Mango explore the strange world of painkillers. Plus: why, 5 years from now, you might be replacing your pills with a phone, a pair of goggles and some green apple air freshener.