depending on how ill you feel you may be allergic to the particular one you are taking - im fine with most antibiotics but trimethoprim made me so sick - it was like i was in a daze all the time and constantly thought i was going to throw up. took me a few days to realise that was what was causing it but i felt so much better after missing just one. If you can then try to complete the course but if its really making you feel awful go back to your gp and see what they can do xx
allergic!?! Its antibiotics! ITs completely normal to feel sick, if not from the foreign toxins you've got pumping around your veins, than the bugs that you're taking it to destroy!
I was really allergic to amoxycillin when i was in hospital last term and was vomiting constantly and couldnt keep any food down for nearly a fortnight. As they had to get antibiotics into me they kept pumping them IV into my arm which was sooo painful. eventually they managed to send me home with liquid suspension form of another type of antibiotic but they tasted horrendous!!! Anyway the point to all this is that in reply to the last post it is quite common to be allergic to antibiotics and certainly does happen. However in answer to the original question it sounds like you are just suffering one of the sideaffects that is associted with taking them and so once you finish the course the symptoms should disappear within a few days (it takes time to get the drugs out of your system). If it gets worse or doesnt go away it might be worth checking it out with the doctor.