It is possible that you may experience some or none of these L-tryptophan 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, make sure to let your healthcare provider know if you develop any side effects while taking L-tryptophan, or if something "just does not seem right." While it may not be a side effect, your healthcare provider will be able to diagnose and treat the problem.