It lasts for 3-6 months with a gradual decrease. Sorry to hear it didn’t help you. If you tried a lower dose, you might get the benefits without the retention?
Do you know how many units they gave you? I started with 100, which is the standard starting point in the U.S. I’ve read that in other countries they start with 300 units! The max a human body can take before being poisoned is 400 units. I myself had to go up to 200 units which continues to work for me. I also get 200 unit in my neck, jaw, and trapezius muscles to prevent migraines. With the 200 units freshly in my bladder, I do have to strain a bit to pee for the first 2-3 weeks but it’s worth it to be able to get more decent sleep at night.
Best wishes that yours wears off fast so you can get respite. UTIs and retention are no fun!