Thank you for the response!
Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
Your friend may be suffering from a condition called essential tremor. Essential tremor is hereditary (it runs in families). The good news about it is that besides the tremor, which is of course very bothersome to some people, it does not have other consequences (it is not neurodegenerative) in the majority of patients, though a minority develop parkinson’s disease.
There are medical treatments for essential tremor. Thus, I do recommend that your friend follow-up with his/her physician. Also, he/she should follow up to ensure that there is not another cause for the tremoring.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.