I am 18 years old, my penis head doesn't come out at all. doctor has asked me to get a. circumcsion. i am a bit scared about it can it have long term side effects?

There are some options other than full circumcision but it is a common procedure practices by many cultures for centuries. Long term side effects are negligible.

It is important that you correct this physical anomaly. Circumcision does not have ill effects, Millions of muslims and jews undergo circumcision. If you are a Hindu, get circumcised will not affect your standing in your religion. It is a medical treatment and not something you chose. Wish you good health!