Inject into the same spot on your abdomen every day for 8 weeks and you’ll regret it — bruising, lumps, and localised lipoatrophy are the predictable outcomes. Site rotation isn’t fussy lab discipline; it’s how you avoid creating problems where there shouldn’t be any.
Where you can inject subcutaneously
The standard subQ injection sites — used in clinical practice for insulin and other subcutaneous drugs for decades — are:
A simple rotation pattern
Most researchers use the abdomen as the primary site because it has the most subcutaneous tissue, the most surface area, and the easiest self-access. The standard pattern:
- Split the abdomen into four quadrants around the navel (excluding the 2 cm immediately around the navel itself).
- Rotate one quadrant per day: Mon = upper-left, Tue = upper-right, Wed = lower-left, Thu = lower-right, Fri = upper-left again (now 4 days from the last injection there), and so on.
- Within each quadrant, vary the spot by 1–2 cm from the previous time. Don’t hit the exact same skin coordinate twice in two weeks.
- If a quadrant becomes bruised or sore, skip it and rotate to the next clean one. Let it heal before returning.
Why rotation actually matters
Three things happen when you repeatedly inject the same spot:
- Lipoatrophy — localised loss of subcutaneous fat. Creates visible dents that take months to fill back in. Most associated with chronic insulin injection but possible with any repeated SubQ.
- Lipohypertrophy — opposite problem: localised fat thickening and scar-tissue buildup. Reduces absorption from that site (compound doesn’t enter circulation as predictably), making dosing inconsistent.
- Localised inflammation and bruising — short-term but accumulating. Repeated trauma to the same capillary network doesn’t have time to heal.
Rotation prevents all three. The 2-cm rule is enough — you don’t need elaborate grid systems, just don’t hit the same patch of skin twice in a row.
Which site for which compound
Three considerations: which sites the compound is studied at, which absorbs predictably, and which is practically accessible.
| Compound class | Primary site | Alternates | Notes |
|---|---|---|---|
| Recovery peptides (BPC-157, TB-500) | Abdomen | Thigh, deltoid | Site-of-injury injection sometimes studied (e.g. near the tendon being treated) |
| GH-axis (HGH, Tesamorelin, CJC-1295) | Abdomen | Thigh | Avoid deltoid for chronic dosing — too small a tissue area |
| IGF-1 LR3 | Abdomen | Site-specific intramuscular (advanced) | Bilateral IM into target muscle is studied but not standard |
| GLP-1 (Semaglutide, Tirzepatide, Retatrutide) | Abdomen | Thigh, deltoid | Manufacturer trial protocols use any of the three; abdomen most common |
| Skin peptides (GHK-Cu, MT-2) | Abdomen | Thigh | Some topical formulations exist for GHK-Cu |
Pinch, angle, depth
For all the above peptides on standard 5–8 mm 30G/31G insulin needles:
- Pinch a fold of skin between thumb and forefinger. This lifts the subcutaneous tissue away from the muscle, giving a clear target.
- Insert at 90° (straight in) for most adults using a short (5–6 mm) needle. For longer needles (8–13 mm) or leaner subjects, a 45° angle reduces the risk of accidentally hitting muscle.
- Don’t aspirate. Pulling back on the plunger before injecting is an old IM-injection habit. SubQ doesn’t need it — the volume is too small and the tissue too vascular-sparse for it to make a difference.
- Inject slowly over 3–5 seconds. Faster causes a burning sensation as the tissue stretches.
- Hold the needle in place for 5 seconds after injecting before withdrawing. Prevents backflow up the needle track.
- Don’t massage the injection site. Some sources recommend it; modern protocols specifically say not to. Massage can change absorption kinetics unpredictably and increase local bruising.