Old medicines and treatments are a mixed bag.
Some work well and, in a few cases, are the original 'miracle drug'. A few thousand years ago people were making tea with willow bark and treating headaches and pain. A closely related compound is aspirin. A thousand years ago honey and lemon was the cough medicine of choice. Recent research has shown that in many cases it is at least as effective as cough medicine with dextromethorphan. The Neti pot is a thousand year-old way of irrigating the sinuses. Human anatomy and physiology hasn't changed much and it still works.
On the other hand some medicine and treatments were useless or so dangerous that we are better off without them. Mercury pills for syphilis had a good side. If you survived the treatment regime you were cured. Down side was a lot of people didn't survive.
Bloodletting, the draining of blood as treatment was pretty much counterproductive. Except in a few rare cases where the person is suffering from a disease that causes overproduction of red cells.
Related but effective and still used: leaches.
Lobotomies have been pretty much relegated the ash heap. Of the methods used, given a choice, go for the 'icepick' lobotomy. Less invasive and likely to kill the patient. It is equally useless but at least you can do it with tools you have in your toolbox. If your going to do something counterproductive not having to buy a tool to do it is a plus.
Herbalism is full of old treatments. Ginger for nausea. Tobacco and/or wormwood for worms. Peppermint for a queasy stomach. Soaking in tea helps with for sweaty and stinky feet.
Before general anesthesia it was known that exsanguniating limb made amputations less painful and less bloody. The limb was tightly wrapped and elevated to push out the blood and numb the limb. A tourniquet was applied to keep the blood out and the operation proceeded in the normal way.
An old, and fairly effect, treatment for the sting of raw skin, like after a large blister breaks, is to apply urine to the raw area. Evidently it is the urea that causes the injury to skin over and stop hurting.