Will anything happen if risperidone is suddenly discontinued?

Unless your doctor tells you otherwise, you should not suddenly stop taking Risperidone even if you feel better and think you don't need it any more. This is because the medicine controls the symptoms of your illness but doesn't actually cure it.
If your doctor recommends you stop taking Risperidone he/she may suggest you gradually taper your dose down so as not to precipitate any withdrawal symptoms eg sweating, nausea, vomiting, difficulty sleeping or tremor.