What is sterile technique?

Sterile technique — also called aseptic technique — is the set of practices that keep a sterile product (vial contents, needle, syringe) sterile through the reconstitution and injection process. Sterility is a probabilistic threshold rather than an absolute state, and every step is designed to keep the probability of contamination very low.

The core practices: wash hands with soap and water and dry with a clean towel before starting. Clean the work surface with 70% isopropyl alcohol and let it air-dry. Verify sterile packaging is intact and within expiration date. Alcohol-swab every vial rubber stopper before each puncture and let it air-dry. Use a fresh sterile needle and syringe for each reconstitution and each injection. Never touch the syringe barrel, plunger, or needle with bare fingers or non-sterile surfaces. Discard any component that touches a non-sterile surface, even briefly. Dispose of all sharps in a sharps container. Never recap needles or reuse them.

The environment matters too. Room air contains bacteria and fungal spores at concentrations that are harmless in most contexts but can inoculate an exposed sterile field if the field is open for long enough. Don't leave sterile packaging open longer than necessary. Don't work near sources of heavy air disturbance. Keep the process focused and quick without rushing the technique itself.