That's all very well but cheap stuff is not always like-for-like.

OK, so the active ingredient and the amount is probably the same but the bulking agents and fillers could be something quite different in a generic product.

A friend had been taking a prescription medication for some time when a repeat prescription turned out to be a generic product. It nearly killed her!

What had happened was that the generic product used Wheat flour as one of the bulking agents. She's allergic to Wheat!