Injection Technique Guide
Best practices for subcutaneous injection technique from clinical guidelines — needle angle, site selection, rotation, aseptic technique, and disposal.
All injection guidance below is adapted from WHO, CDC, and clinical nursing guidelines for subcutaneous administration. For educational purposes only.
Subcutaneous Injection Basics
Subcutaneous (Sub-Q) injection delivers a compound into the fatty tissue layer just beneath the skin, above the muscle. This is the standard route for nearly all research peptides. Sub-Q injections are generally less painful than intramuscular injections and provide reliable, consistent absorption for most peptide compounds.
Step-by-Step Injection Technique
- Prepare your supplies. Gather the reconstituted peptide vial, a fresh sterile insulin syringe, two alcohol swabs, and a sharps container.
- Wash hands thoroughly with soap and water for at least 20 seconds. Dry with a clean towel.
- Clean the vial stopper with an alcohol swab. Allow 30–60 seconds to air dry before puncturing.
- Draw your dose. Insert the needle through the stopper. Draw back the plunger slightly to allow air in, then invert the vial and draw the calculated dose volume. Remove any air bubbles by tapping and gently pushing the plunger up.
- Select an injection site. Common sites: abdomen (at least 2 inches from navel), outer thigh, upper arm. Rotate sites systematically — never inject the same spot twice in a row.
- Clean the injection site with an alcohol swab. Allow to air dry completely (30–60 seconds) — injecting through wet alcohol can cause stinging and irritation.
- Pinch the skin. Grasp 1–2 inches of skin between thumb and forefinger to lift the subcutaneous tissue away from the muscle.
- Insert the needle. At a 45–90° angle (45° for very thin individuals with minimal fat; 90° for most people with adequate subcutaneous tissue). Insert with a single, smooth motion.
- Do not aspirate. Current clinical guidelines (WHO, CDC) indicate aspiration is not necessary for subcutaneous injections — inject slowly and steadily without pulling back the plunger first.
- Inject slowly. Push the plunger at a steady, gentle pace. Wait 2–3 seconds after the dose is delivered before withdrawing.
- Withdraw and dispose. Remove the needle at the same angle it was inserted. Gently apply pressure with a clean cotton ball or gauze if needed — do not rub. Dispose of the used syringe immediately in a sharps container. Never recap needles.
Injection Site Rotation
Rotating injection sites prevents lipohypertrophy (local fat buildup) and maintains consistent absorption. A simple systematic rotation:
- Abdomen: Divide into quadrants. Rotate through each quadrant.
- Outer thighs: Alternate left and right.
- Upper arms: Outer aspect only; alternate left and right.
Allow at least 1–2 cm between injection sites. Do not use a site that is bruised, scarred, inflamed, or shows lipohypertrophy.
Needle Selection
| Gauge | Diameter | Best For |
|---|---|---|
| 28–31 gauge | Thin (0.36–0.31 mm) | Standard subcutaneous peptide injection; minimal discomfort |
| 25–27 gauge | Medium | Higher-viscosity solutions; adequate for most sub-Q uses |
| 5/8" length | 15.9 mm | Standard for sub-Q; ensures proper tissue layer |
| 1/2" length | 12.7 mm | Suitable for thin individuals; most insulin syringes |
Safety and Disposal
- Always use a new, sterile syringe for every injection. Never reuse needles.
- Never share syringes or needles.
- Dispose of used needles immediately in an approved sharps container — never in regular trash or recycling.
- When the sharps container is ¾ full, seal and dispose per local guidelines (many pharmacies accept used sharps containers).
- Never recap needles after use — recapping is a leading cause of needlestick injuries.