[ksaj]

There are actually a number of drugs where they specifically state the actual mechanism of action is unknown, but they do know from proper and continued clinical trials that the drug does indeed work. A lot of pain killers are in that category.

Here is a list of 68 drugs that are known to work, but apparently we don't know how or why:

https://en.wikipedia.org/wiki/Category:Drugs_with_unknown_me...