Subcutaneous (Sub-Q) Injection Guide, Step by Step
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Sub-Q injection guide

6 min read · Also in the Dose Track app under Learn · Updated

Short answer: A sub-Q injection puts medicine into the fat layer under the skin, not into muscle or a vein. Wash your hands, swab and dry the skin, insert a short needle in one smooth motion, push the plunger slowly, and put the needle straight into a sharps container. Use a new spot each time.

Steps

  1. Wash your handsSoap and water for about 20 seconds. Dry with a clean towel.
  2. Draw the doseSwab the vial stopper and let it dry. Draw your dose, then hold the syringe needle-up, tap the barrel so bubbles rise, and push them out. Check the dose line again.
  3. Pick and check a siteUse the belly (at least 2 inches from the navel), the front or outer thigh, or the back of the upper arm. Skip skin that is bruised, red, hard, scarred or lumpy.
  4. Clean the skinWipe with an alcohol swab and let it dry fully. Injecting through wet alcohol stings.
  5. Insert the needleWith a short needle (4 to 6 mm), insert straight in at 90 degrees. If you are lean or the needle is 8 mm (5/16 inch), pinch up a fold of skin first; some people also angle it to about 45 degrees.
  6. Inject slowlyPress the plunger steadily until it stops.
  7. Withdraw and pressPull the needle out at the same angle, let go of the pinch, and press lightly with gauze if needed. Do not rub.
  8. Dispose of itPut the syringe straight into a sharps container. Do not recap it.

What sub-Q means

Subcutaneous means under the skin, into the fat layer above the muscle. It is the usual route for insulin, GLP-1 pens like Ozempic and Zepbound, and most peptides. Medicine is absorbed from fat more slowly and evenly than from muscle.

Supplies

  • Insulin syringes or pen needles. Insulin injection guidelines (FIT 2016) favor the shortest needle available: 4 mm pen needles, or 6 mm on syringes. Common sizes are 29 to 31 gauge; a higher number is a thinner needle.
  • Individually wrapped 70% alcohol swabs.
  • An FDA-cleared sharps container, or a heavy-duty plastic household container with a tight lid until you get one.
  • Good light and a clean, hard surface.

If needles make you anxious, ask a pharmacist about a numbing cream. EMLA's data sheet says to apply it at least an hour before, under a dressing.

Where to inject

The belly, thigh and upper arm all work. The belly is easiest to see and reach. The back of the upper arm is hard to do yourself; the Zepbound instructions say someone else should inject there.

Move to a new spot every time, at least a finger-width (about 1 cm) from the last one. Repeated shots in one spot can cause lipohypertrophy, a firm or rubbery lump where medicine absorbs unevenly. See injection site rotation.

Air bubbles

A small bubble injected under the skin is not dangerous. The air embolism worry applies to injections into a vein. You still clear bubbles because they take up room meant for medicine, so you get less than you measured. A tiny bubble that will not tap free is not worth chasing.

What is normal afterward

Normal: a small bump, mild redness, light itching, or a small bruise that fades.

Get medical advice for: redness or swelling that spreads or gets worse over hours or days, warmth, pus, red streaks from the site, a painful hard lump that does not go away, or fever.

Call emergency services for: trouble breathing, swelling of the face or throat, or hives all over.

Getting rid of needles

Put used needles in a sharps container right away. Never put loose needles in the trash or recycling, and never flush them. When the container is about three quarters full, follow your local rules; the FDA keeps state-by-state details at fda.gov/safesharpsdisposal. Many areas have drop-off sites or mail-back programs.

Key points

  • Sub-Q means into the fat layer under the skin.
  • Short needles (4 to 6 mm) go straight in; pinch up skin with longer needles or if you are lean.
  • Let alcohol dry, inject slowly, and use a new spot every time.
  • Spreading redness, warmth, pus or fever needs medical advice.

See also: Site rotation in Dose Track · U-40 vs U-100 syringes

This guide is general education, not medical advice. Follow your medicine's label and your prescriber.

Compounds in this guide

SemaglutideCompound guide in the Dose Track library. TirzepatideCompound guide in the Dose Track library. BPC-157Compound guide in the Dose Track library.
Injection site rotationInjecting into the same spot again and again can cause lipohypertrophy: firm, rubbery lumps under the skin… Sterile use and safetyEvery injection skips your skin's defenses, so keep anything that goes into your body from touching… How to reconstitute a peptideReconstituting means adding liquid to the powder in a vial so you can draw doses. Use bacteriostatic water… Using an injection penEvery prefilled pen comes with FDA-approved Instructions for Use (IFU), and the steps differ from pen to…

Frequently asked questions

Should I pull back on the plunger to check for blood?+
Pen and insulin instructions for sub-Q injections do not include this step. Insert, inject slowly, and withdraw.
What needle length is best for sub-Q?+
Insulin injection guidelines favor the shortest available: 4 mm pen needles or 6 mm syringe needles, inserted at 90 degrees for most adults.
Is a small air bubble dangerous?+
Not under the skin. Clear bubbles anyway so you get the full dose.

Sources

  1. Frid AH et al. New Insulin Delivery Recommendations. Mayo Clin Proc 2016;91(9):1231-55
  2. Ozempic prescribing information and Instructions for Use (Novo Nordisk)
  3. Zepbound prescribing information and Instructions for Use, single-dose pen and KwikPen (Eli Lilly)
  4. FDA, Safely Using Sharps (Needles and Syringes) at Home, at Work and on Travel
  5. FDA, Best Way to Get Rid of Used Needles and Other Sharps
  6. EMLA cream data sheet (Medsafe, New Zealand)

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