Opium doesn't cure anything medically. It can be used as a powerful pain reliever however, as strong as almost anything they give you in the hospital, if you have enough.

Made into a tea, you will only get a little "high" but it will stop most non-life threatening discomfort.

If smoked it is stronger and will create a powerful (and highly addictive! So don't use it for getting high!) euphoric sensation, and an even stronger feeling of pain relief.

I don't know how to do it myself, but Morphine, which is pretty much the most powerful pain reliever we have to my knowledge, is made from Opium.

It is a bit like using a nuke to kill a mouse to use it on a headache, but if things are seriously bad in the world, it may save lives by making surgery possible for instance or give people a chance to relax and heal when they otherwise might not.