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