Nicotine
"Patches are really useful. I had tried quitting several times but it never worked. There wasn't a single day without smoke in my last 8 years. But it has been 4 days since I'm on the patches now and I haven't even had a single cigarette. I'm sure I'll not smoke again.

But I experienced a side effect, it causes joint pains, my left elbow starts paining if I put it on my left arm and same goes with right. But it's a very less price to pay to quit."