Double-blind trials.
Half of the patients get the drug.
Half don’t get the drug. They get a placebo.
That’s something that doesn’t do anything.
The patients don’t know if they’re getting the drug.
The doctors don’t know either.
The pills look the same.
The list of who got the drug and who got the placebo isn’t known until the trial is over.
Well, unless the patient is extremely rich.
Then, they’re taken out of the trial.
And just given the drug.
If it turns out to be horribly toxic, oh well.
Plenty more money to pay for further research, right?