Time bomb

The medication that my wife is taking warns that it can cause diarrhea “weeks to months” after taking it. 

So when she’s suffering from diarrhea in March of 2012, should she remind her doctor that less than five months ago, she was taking penicillin?

Seriously?

“Yes, doctor.  I had some questionable shellfish last night, and I just returned from a vacation in Mexico City where I drank tap water from public restrooms, but you should also know that 158 days ago, I was taking a medication that was probably responsible for this illness.” 

Better question: 

How were the drug companies able to link incidents of diarrhea months after taking a pill to the medication?