You may experience some or none of the Asendin side effects explained above. Unfortunately, there is no way for your healthcare provider to know beforehand if you will have side effects from a medicine that you have never tried. Therefore, be sure to let your healthcare provider know if you develop any side effects or if something "just does not seem right." While it may not be an Asendin side effect, your healthcare provider will be able to diagnose and treat the problem.