4.5 months and promethazine is still working as intended.
However, even though I use it 1-2 times a week, I started to feel slight pinching pain in both of my kidneys, when I lay on bed specifically.
I asked the pharmecist if it can cause any kidney issues, he replied that promethazine isn't intended for long term use.
Before I tried this medicine my Urologist already gave me the ok to use it long term, so I'll have to discuss with him to understand the causes of this dull pain a bit more.