Do you have any sources for it being harsh? I'm curious because I've been on antibiotics for 2 years (yes really) and this is the one I tolerate the best.
I was also on doxycycline for over 2 years, and barring a slightly dodgy tummy for the first 48 hours (fairly typical for antibiotics), I didn't notice any adverse affects. It did transpire that my doctor had 'forgotten' I was still on it though (I was only meant to be on it for 6 months!), so I did wonder if there were any adverse affects of taking it for that long!