I went to my doctor yesterday with a UTI, also my temperature was slightly up at 100^F. I was prescribed cefalexin (500mg 2 per day for 5 days). Just as other people have commented, these pills were supplied in a plain box with no instructions or info about possible side affects.
After a couple of hours of taking this drug I started to feel faint along with hot & cold sweats. In the evening I couldn't face anything to eat. I then took my temperature, it had gone up to 105^F!
However by about 10pm, 6 hours after taking 1st pill, I felt much better.
When I woke up this morning I felt fine. Then I took another dose of cefalexin!! Within an hour I was feeling completely drained and nauseous again!
Thankfully the UTI seems to have cleared up, so I'm thinking of giving up on these pills.