anesthetic injection
A medical injection that numbs a part of the body or induces unconsciousness.
I received an anesthetic injection at the dentist.
We will give you an anesthetic injection before the surgery.
麻酔 is the general term for anesthesia, while 麻酔注射 specifically refers to the injection form.
注射 is a general injection; 麻酔注射 specifies an anesthetic injection.
Compound of 麻酔 (anesthesia) and 注射 (injection).