I've just been prescribed doxycycline (100mg, 1/day) for a non-ME-related problem. I was wondering if it would muck up my gut so did a quick search on PR and find (surprisingly) that some people consider it beneficial for ME/CFS because it has a cytokine-suppressing effect (I think). Views? I've had some improvement in my OI which I think is due to some improvements I've been working on with my gut flora and I'm a bit worried about messing that up. I don't know if this is one of the antibiotics that wreaks havoc on your gut flora.