Injection sites & rotation

Testosterone can go into three intramuscular sites and two subcutaneous sites — and the site you pick, plus how often you move between them, affects comfort, absorption, and whether you end up with a hard lump under the skin a year from now.

Once you know how to draw up a dose and get the needle in — covered in our step-by-step injection guide — the next question is where. Testosterone has a short list of approved injection sites, and each one has its own landmarks, needle depth, and trade-offs. This guide maps out the intramuscular (IM) and subcutaneous (SubQ) sites in detail, explains why rotating between them matters more than most people realize, and gives you a rotation pattern you can actually follow. If you haven't settled on a route yet, our SubQ vs IM comparison covers how the two differ in absorption and convenience before you get to site selection.

Approved injection sites: an overview

Testosterone cypionate and enanthate are FDA-labeled for intramuscular injection, with subcutaneous dosing used as an increasingly common alternative that a growing body of research supports as comparably effective¹. IM sites go deep into muscle tissue; SubQ sites stay shallow, in the fat layer just under the skin. Which sites are available to you depends on the route your prescriber assigned, not personal preference alone — the Endocrine Society's clinical practice guideline on testosterone therapy treats route and site as part of the prescribed protocol, reviewed alongside your labs².

Intramuscular sites: landmarks and technique

Ventrogluteal (hip) — the preferred IM site

The ventrogluteal site sits on the side of the hip, not the back of the buttock. It has become the preferred IM site in nursing and pharmacology literature because the subcutaneous fat layer over it is comparatively thin, the underlying gluteus medius muscle is thick and well-developed, and there are fewer major nerves and blood vessels nearby compared with the older dorsogluteal site³. A widely taught landmarking method — sometimes called the V-method — places the heel of your hand on the greater trochanter (the bony point at the top of the thigh bone), the index finger on the anterior superior iliac spine (the bony point at the front of the hip), and the middle finger traced back along the iliac crest; the injection goes into the triangle formed between the index and middle fingers. Despite the evidence favoring it, one study found that roughly three-quarters of nurses surveyed had never used the ventrogluteal site in practice, most often citing uncertainty about locating it correctly³ — which is exactly why a prescriber or nurse should walk you through the landmarks in person before you try it solo.

Deltoid (upper arm)

The deltoid is the easiest IM site to reach solo, which is part of why it's popular for self-injection. It's also the site with the least room for error: a systematic review of the neurovascular anatomy under the deltoid found that injecting too high risks the axillary nerve and posterior circumflex humeral artery, and proposed a site roughly four fingerbreadths (about 9–10 cm) below the midpoint of the acromion — the bony ridge at the top of the shoulder — as a safer landmark than sites closer to the shoulder joint⁴. In practice, that means injecting into the thickest part of the muscle at or below its midpoint, never into the upper third near the shoulder.

Vastus lateralis (outer thigh)

The vastus lateralis runs along the outer thigh and is often the first IM site taught to patients because it's easy to see and reach without help. A cadaver and cross-sectional imaging study identified the midpoint between the greater trochanter (hip) and the lateral epicondyle (the bony bump above the knee) as the safest injection point, with no major nerves or blood vessels found within a centimeter of that spot in either living subjects or cadavers — a contrast to the nearby rectus femoris, which the same study found sits closer to the femoral nerve and should generally be avoided⁵.

Subcutaneous sites: abdomen and thigh

SubQ testosterone goes into the fat layer rather than muscle, typically in the abdomen (a couple of inches from the navel, rotating around the beltline) or the front/outer thigh. Because the needle is shorter and finer, SubQ sites are generally easier to self-inject without a mirror or an awkward reach — one reason some prescribers default new patients to this route. A study in transgender men found SubQ testosterone cypionate produced testosterone levels comparable to IM dosing at the same weekly total⁶, and a broader 2022 review concluded SubQ injection is a "safe, practical, and reasonable option" for testosterone therapy generally¹. For a fuller breakdown of how the routes compare beyond site selection, see our SubQ vs IM guide.

Why rotation matters: lipohypertrophy and scar tissue

Injecting the exact same point over and over — whether IM or SubQ — irritates the tissue underneath and, over months to years, can build a firm or fatty lump called lipohypertrophy, along with fibrous scar tissue at deeper IM sites. Most of the direct evidence on this comes from insulin injection research, where it's been studied far more extensively than with testosterone: one case-based review found that repeated use of the same site without rotation was a consistent driver of lipohypertrophy, and that once it develops, absorption from that site becomes erratic — sometimes faster, sometimes slower, sometimes trapped altogether⁷. The underlying mechanism (repeated mechanical and possibly lipogenic trauma to the same patch of tissue) isn't testosterone-specific, but there's no anatomical reason to think muscle or fat responds differently to a testosterone needle than an insulin one, and it's the same logic StatPearls' overview of IM injection technique applies when it stresses varying the site and matching needle length to the tissue being injected⁸.

A simple rotation schedule you can follow

You don't need a complicated system — you need to reliably avoid the same exact point two injections in a row. A pattern that works for most weekly or twice-weekly protocols:

1. Pick 2–4 approved sites your prescriber has cleared for your protocol (for example: left thigh, right thigh, left ventrogluteal, right ventrogluteal)
2. Move to the next site in the list every injection, cycling back to the first only after you've used the others
3. Within a site, shift the exact point by at least an inch each time — don't return to the identical spot even within the same general area
4. Leave at least 1–2 weeks before reinjecting the exact same point
5. If you're on a daily or every-other-day SubQ protocol, alternate left and right sides of the abdomen and move at least an inch between consecutive injections
6. Keep a simple log of site and date — a body-map log makes this easier than trying to remember which hip you used last Tuesday

Signs a site needs a break

Some tenderness or a small bruise for a day or two after an injection is normal at any site. These signs suggest a site needs to rest and be evaluated by your prescriber rather than simply rotated around:

1. A firm or fatty lump that doesn't soften within a week
2. A spot that feels different to the touch than surrounding tissue — numb, dense, or rubbery
3. Spreading redness, warmth, or swelling beyond the immediate injection point
4. Increasing pain with each injection at that specific site, rather than the usual mild soreness
5. Visibly uneven skin texture or a dent developing over the site

Self-injecting vs. partner-assisted sites

The deltoid, vastus lateralis, and abdomen are the sites most people learn to self-inject without help, since all three are visible and reachable without contorting. The ventrogluteal site is harder to reach and see on yourself, which is why it's more often taught as a partner-assisted site, or why some patients skip it entirely in favor of the thigh or arm for solo dosing. There's no requirement to use every available site — if you're self-injecting, it's reasonable to build a rotation out of just the sites you can reliably reach and landmark correctly, and confirm that plan with whoever trained you.

Common mistakes

1. Sticking to one "favorite" site because it's familiar, rather than rotating on a schedule
2. Guessing at landmarks instead of having a nurse or prescriber confirm them at least once in person
3. Injecting into a site that's already sore, lumpy, or bruised from the last dose
4. Using an IM-length needle at a SubQ site (or the reverse), which changes how deep the dose actually lands
5. Not tracking which site was used last, leading to accidental repeats

A body-map that shows your last few injection points at a glance removes the guesswork — Peptide Me's site tracker logs each injection to a specific point on an 11–14-zone body map and nudges you toward the site you haven't used recently, so rotation happens automatically instead of relying on memory. Pair it with the TRT dose calculator to keep site, dose, and schedule in one place, and visit the TRT hub for the rest of the monitoring and dosing picture.

Disclaimer: this article describes general injection-site anatomy and rotation principles and is not medical advice. Testosterone cypionate and enanthate are prescription, controlled medications — which sites are appropriate for you, and how to locate them safely, should be confirmed by the clinician or nurse managing your protocol, ideally with hands-on demonstration before you self-inject at a new site for the first time.

FAQ

References

Primary sources — PubMed / NEJM / The Lancet.

1. Figueiredo MG, Gagliano-Jucá T, Basaria S. Testosterone Therapy With Subcutaneous Injections: A Safe, Practical, and Reasonable Option. J Clin Endocrinol Metab. 2022;107(3):614-626. https://academic.oup.com/jcem/article/107/3/614/6410585
2. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. https://academic.oup.com/jcem/article/103/5/1715/4939465
3. Gürol Arslan G, Özden D. Creating a change in the use of ventrogluteal site for intramuscular injection. Patient Prefer Adherence. 2018;12:1749-1758. https://pmc.ncbi.nlm.nih.gov/articles/PMC6145361/
4. Charmode S, Sharma S, Kushwaha SS, et al. Deltoid Intramuscular Injections: A Systematic Review of Underlying Neurovascular Structures to the Muscle and Proposing a Relatively Safer Site. Cureus. 2022;14(4):e24172. https://pmc.ncbi.nlm.nih.gov/articles/PMC9110073/
5. Nakajima Y, Fujii T, Mukai K, et al. Anatomically safe sites for intramuscular injections: a cross-sectional study on young adults and cadavers with a focus on the thigh. Hum Vaccin Immunother. 2019;16(1):189-196. https://pmc.ncbi.nlm.nih.gov/articles/PMC7012163/
6. Spratt DI, Stewart II, Savage C, et al. Subcutaneous Injection of Testosterone Is an Effective and Preferred Alternative to Intramuscular Injection: Demonstration in Female-to-Male Transgender Patients. J Clin Endocrinol Metab. 2017;102(7):2349-2355. https://academic.oup.com/jcem/article/102/7/2349/3098651
7. Mokta JK, Mokta KK, Panda P. Insulin lipodystrophy and lipohypertrophy. Indian J Endocrinol Metab. 2013;17(4):773-774. https://pmc.ncbi.nlm.nih.gov/articles/PMC3743397/
8. Polania Gutierrez JJ, Munakomi S. Intramuscular Injection. StatPearls [Internet]. 2023. https://www.ncbi.nlm.nih.gov/books/NBK556121/