Penicillin gives my stomach hell.
Zithromax did me in once. Vomiting would not stop. Had to go to ER for IV of the wondrous drug Zofran. Though I’ve since found out it’s not so effective for an actual stomach flu. Though to be fair it was a particularly bad case I had that Christmas.
I’ve never had any reaction to antibiotics, except that one time with swelling after penicillin.
It always amuses me when you’re given a drug that instructs “Don’t take this if you are allergic to it.” How the heck do you know, until you take it once?