Short answer: Every injection skips your skin's defenses, so keep anything that goes into your body from touching anything unclean. Wash your hands, swab vial tops and skin and let them dry, use a new needle every time, never touch the needle, and throw out any vial that looks cloudy. Spreading redness, warmth, pus or fever means see a clinician.
Why it matters
Infections from injections range from mild redness to an abscess (a pocket of pus that may need draining), cellulitis (spreading skin infection that needs antibiotics) and, rarely, infection in the blood. Most are avoided with simple, consistent habits.
The core rule
Nothing unclean should touch anything that goes into your body: the needle, the inside of the syringe, the solution, the vial stopper (before swabbing) and your skin (before swabbing). Germs on a stopper end up in the vial and in every dose drawn after.
Hands
- Wash with soap and running water for at least 20 seconds, including under nails and between fingers.
- Dry with a clean paper towel.
- Do not touch your phone or other surfaces before you start.
- Gloves are optional. If you use them, put them on after washing; they do not replace washing. Nitrile avoids latex allergy problems.
Alcohol swabs
- Use 70% isopropyl alcohol swabs. The CDC says alcohol works best at 60% to 90% in water; it needs some water to kill germs well.
- Swab the vial stopper every time you puncture it, and swab your skin. One swab per surface.
- Let it dry before you inject. Wet alcohol stings and is carried into the skin. Do not blow on it to speed it up.
Needles and syringes
- Use a new needle every time. Pen labels say so, and a used needle is no longer sterile and is duller.
- Never touch the needle. If you do, replace it.
- Do not recap by hand. Put the used syringe straight into the sharps container. If you must recap, use a one-handed scoop.
- Never share needles, syringes or pens.
- Check for a bent or damaged needle before use.
Vials you use more than once
- Swab the stopper before every draw and let it dry. Go through the center of the stopper.
- Mix multi-use vials with bacteriostatic water, which contains a preservative (0.9% benzyl alcohol). Sterile water has none and is for single use.
- Date the vial when you first puncture it. Clinics discard multi-dose vials after 28 days unless the maker says otherwise.
- Throw it out if it turns cloudy, has particles or changes color.
Workspace
Use a hard surface you have wiped clean, in good light. Keep pets and young children out, and have everything laid out before you wash your hands.
When to get care
Usually normal: a small welt or mild redness that fades within an hour or so; mild soreness for a day or two.
See a clinician for:
- Redness or swelling that spreads or keeps getting worse.
- A warm, painful lump, or a soft, fluid-filled lump (possible abscess).
- Red streaks spreading from the site.
- Fever of 38 °C (100.4 °F) or higher.
Key points
- Keep anything that enters your body away from anything unclean.
- Swab stoppers and skin with 70% alcohol and let them dry.
- New needle every time; never touch, share or hand-recap it.
- Spreading redness, a warm or soft lump, red streaks or fever need care.
See also: Side effects log in Dose Track
This guide is general education, not medical advice. Follow your medicine's label and your prescriber.
Why let the alcohol dry before injecting?+
Wet alcohol stings and gets carried into the skin. Letting it dry also gives it time to work.
Can I reuse a needle if I only used it once?+
No. A used needle is no longer sterile and is duller. Pen labels say to use a new needle every time.
What does an infected injection site look like?+
Redness or swelling that spreads or worsens, warmth, pus or a soft lump, red streaks, or fever. See a clinician.