How long do antibiotics take to have an effect on UTI/kidney infection?

[ReesesPieces100]

I've made a few threads now about similar related things however I've no idea what I'm dealing with. I swear I'm not a troll
But I've been on nitrofurantoin since Friday for a suspected UTI or kidney infection. GP thinks this may be something that has been long term and they are going to explore further.
However, since the antibiotics I haven't really noticed an improvement. I have a lot of pressure and pain in my lower/mid back and lower abdomen. The most annoying thing is an itchy sensation in my bladder, i'm constantly running to the toilet but do not always go.
I can't really hold any pee either, I keep wetting myself. I have always had a weak bladder but this is next level. I can't do anything without the twitchy sensation and peeing myself if I can't get to the toilet straight away.
The GP is calling me tomorrow after doing urine cultures etc but should I be noticing an improvement by now on the AB's? Thanks

I had nitrofuantoin for a uti once and it wasn't the right antibiotic for whatever bacteria is was caused by. Gp switched me onto another and I started to improve over the next couple days

I had 2 lots of nitrofurantoin and 1 lot of trimethoprim, however I had a negative culture after the second lot of nitrofurantoin so it did clear the infection but the doctor gave me the others as I still had symptoms. I ended those ones last Thurs and still have some symptoms now. It's almost 3 weeks since my symptoms first started. You should start to feel some relief though, even if its just a little so you may have the wrong antibiotics, give your gp a ring in morning. Also I rec drinking lemon barley water, it's been a life saver and get some d-mannose too. Good luck, uti's are horrendous!