Seriously? Insulin, just off the top of my head.
Yes, there are some drugs/chemicals, that are not produced in the body, that we use to treat symptoms - sometimes in the same manner that naturally-produced drugs will (such as the average painkiller). There are other drugs that are used for - well, curing cancer? Doesn't that help return the body to health?
You are really pushing it here, Battunga3; the medications that are prescribed by the average qualified medical professional have a wide range of purposes. Not all are directly able to return you to health, not all are even intended to return you to health - but they are often preferable to the alternative - and I say this as someone with a condition for which drugs are not helping. And in the case of pain (just returning to a simple example), being without pain is healthier than living with it.