My 3-year old son received a present for the holidays this year that I don't think he will appreciate until he gets much older (or he may never appreciate it).  He learned how to stop sucking his thumb!  This may have been the easiest intervention I have ever done.  All I had to do was paint a bitter tasting nail polish on his thumb. He tasted it one time and has never tried to suck his thumb again.  Of course, we have also used positive methods during the process.  He is reminded of what a "big boy" he is and we tell him how proud we are of him for learning to stop sucking his thumb. 

I think many parents are afraid to use taste aversion (using a bad taste to deter behavior) to stop thumbsucking.  While most experts definitely agree that positive methods should be used over punishment procedures, I think there are some circumstances when an aversive intervention might actually be the best choice.  Thumbsucking is an incredibly hard behavior to stop and positive interventions alone are not very likely to be successful.  I feel like I need to put in a disclaimer here to state that I am not saying positive interventions can't or don't work.  I am saying they aren't very likely to work unless you have the ability to spend an enormous amount of time working on teaching your child to stop sucking his thumb, including many sleepless nights.  This point, is exactly why I think it actually might be a nicer alternative to use a quick and easy-to-use taste aversion procedure.   

If you decide to use taste aversion, it is important to use a product that actually works.  I used Mavala Stop and I would definitely recommend it. It had the right amount of bitter taste to work perfectly.  It's not so strong that it makes your child upset or cry, but its strong enough to deter the behavior.  My son did not experience any anxiety or pain using taste aversion.  He tasted it one time, made a funny look on his face, asked for a glass of milk, and never tried it again.  From that point forward, the entire experience has been completely positive because he has received nothing but praise for being a "big boy" who doesn't suck his thumb anymore.  He is very proud of himself and announces to everyone that he is a "big boy now."