[Hannah LS (OP)]

Wassem asks:

How does a pain relief drug target the actual area of the body where the pain is?

What do you think?

[evan_au]

With a local anaesthetic, it targets a particular area by being injected into that specific area, or into the nerves sensing pain in that area.
Dentists are quite good at targeting specific areas - although you may drool for a while afterwards...

For analgesics taken by mouth or breathed in via the lungs, the bloodstream carries them to all parts of the body, so it has a general pain relief effect - but it also means that any side-effects will be more systemic, like the painkillers that can damage your liver (in susceptible individuals).

One pain medication in Australia was fined for advertising that implied that it could target specific sources of pain. Their more recent advertising now implies that it can cure all pains...

[chris]

We answered how painkillers know where it hurts on the Naked Scientists a few years back.

We also tackled it on our Ask! The Naked Scientists phone-in show in 2011:

https://www.thenakedscientists.com/podcasts/ask-naked-scientists/how-do-painkillers-know-where-it-hurts