You may experience some or none of these 5-HTP side effects. 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 5-HTP. You should also let your healthcare provider know if you develop something that "just does not seem right." While it may not be a side effect of 5-HTP, your healthcare provider will be able to diagnose and treat the problem.