My age is 18+. I have a high blood pressure. My doc give me a tablet losar h.Is it have any side effect? Or will it get me any sexual trouble in future?

Try it. That medicine is very good for high blood pressure. Not known to produce any impotence or sexual side effects. It's important to get your BP down. Go ahead and follow your doctors advice.
At 18?????? At that age it is the autonomic (automatic) nervous system that is at fault. Commonest cause is sugar that induces vitamin b deficiency. Sounds strange? It is a reflection on U.S. Diet.