A friend said that they were able to get their prescriptions filled cheaper in Paris. Is that true? I thought that the exchange rate regarding the Euro wasn't very good for the dollar....or is it that prescriptions in general are cheaper? Would I just need to bring my doctor's written prescription?

The answer here is "it all depends" on what type of prescription you're trying to fill and if a Pharmacy in France can, in fact, fill it. France has Social Medicine, much different than anything you're used to at home and yes, prescriptions, in general, are much cheaper.
One example is that a large number of over the counter drugs available in France are only available with a prescription in the States at a heavy markup.

If you plan to buy prescriptions outside N. America, you need to know what name it goes buy outside N. America. Many OTC and prescription drugs have different names depending on where they are sold.

Prescription drugs are often cheaper in France--the government subsidizes the pharmaceutical industry to an extent to keep prices reasonable. Sigh.

Prescriptions are cheaper in many countries compared to the US. In fact, probably the majority of them.

Of course you would need to bring a prescription (if they'll fill it) what do you think, they just give you drugs if you ask for them.