Is low blood pressure bad for you?

Depends: Low BP or "hypotension" (less than 120/80) is always bad if happened all of a sudden. It has got several reasons. Of those reasons the common bad ones are 1)severe dehydration, any cause of 2)bleeding, any where in our body, 3)infections, hormonal dysfunction, and 4) heart conditions with failure, or hear attacks, to name a few. For some it can be a normal finding too, as low as 80/60.

Define Low: Generally, no. If we were all cavemen/women running around without salt and getting plenty of exercise, our top number (systolic) would be somewhere in the 90s our whole lives. Cheers!