I have been receiving chin Botox consistently for 5 to 6 months, and it seems to be effective and no resistance has developed. There have been no major side effects. Botox is great for your chin! They say that if you get it consistently, your muscles won't get bigger, but the strange thing is... I started getting muscles in my jaw lol. I got Botox on my nose and it really hurt... I felt like it was slightly less wide open, but I didn't know if it had a big effect, so I got it once and haven't had it since. I also got Botox for calf reduction, but I didn't feel like it had much of an effect. It was expensive because it involved a lot, but I got it once and it didn't work.