The idea that a drug is only for one particular condition, (or...

The idea that a drug is only for one particular condition, (or one particular species) is incorrect. What is aspirin for - headache? Ok, well we best not use it for thinning the blood, because that would be ridiculous. What is ketamine - a horse tranquilizer? Ok, well better not use it for a human with CRPS because it's only for horses.

A drug is indicated for whatever and whenever it works. The "it's a worming medication!" narrative is run by Big Pharka, and is lapped up by those who can't think for themselves.