I have taken a beta lactam antibiotic before. When I had strep throat, this was the only time I had ever been given straight penicillin.
It meant serious business. It got busy right away at eliminating that bacteria, and I felt a little better the same day.
This says a lot, because my throat was almost swollen shut when I went into the exam room. My fever was over 100, and I felt like I needed to be in the emergency room.
I could actually swallow a little bit of soup and water later that day. Also, my fever went down to 99, so I didn't feel so disoriented.