Does circumcision at age 20 hurts?

"Local anesthesia for adult circumcision is usually given by a dorsal penile nerve block and/or a ring block. Specifically lidocaine without epinephrine is injected at the penile base deep into Buck's fascia, where the dorsal nerves emerge from under the pubic bone." So, there should be no pain during the surgery. Following the procedure, oral pain medications can be administered as needed.

It will be done under regional or general anesthesia so you wont feel a thing. Post operative discomfort is nothing which oral pain medicine cant handle. So you should be OK