Lima I just went and asked "you know who!"

 

And he said that they "can" work but are not neccessarily known to be successful. (medically speaking)

 

I.E. everything in medicine is not a guarantee although many medications are likely to have the desired affect. Such as 10 people popping a sugar pill for headaches. And 3 of them come back and say the sugar pill worked.  Whereas 10 people who pop paracetemol and 7 of them come back and say that it cured them.. Whereas 3 may say it didn't work.

 

So that is what is thought about cough medicine.