I have been on Betaseron for 9 years. I have taken one 2 week shot vacation a couple of years ago. I took another recently -- I was scheduled for surgery - unrelated to MS -- and skipped the shot the night before my surgery - then felt pretty bad from the surgery and stayed off for 2 weeks.
When I started the shots up again, " shot hangovers" started up again. Plus, some funky chest pains. Perhaps my head is in the sand, but the chest pains don't happen except the morning after my shot --
I haven't called my neuro yet or my regular internist

Any thoughts on this ?