How to rotate injection sites

We read seven FDA labels in full to write this page, looking for the rule everyone assumes exists. It does not. Exactly one testosterone product in the United States tells you to change injection sites, and what it tells you is narrower than any diagram you will find online: alternate between the left and the right buttock. Two sites. The reference testosterone cypionate label names the gluteal muscle and says nothing whatever about changing sites. The subcutaneous testosterone autoinjector specifies the abdomen and never uses the word rotate.

Every detailed rotation instruction that does exist belongs to a subcutaneous product, and every reason any of them gives is a problem of subcutaneous tissue — lipoatrophy, lipodystrophy, localized cutaneous amyloidosis, tissue atrophy. The only numeric distance in any label we read is one inch, and it is on a growth hormone label for a subcutaneous injection. The whole published evidence base for site rotation is insulin, in people with diabetes, measuring a lesion that forms in fat.

That does not make rotation pointless for an intramuscular oil. It makes it undocumented, which is a different thing and is worth knowing the difference between. This page prints what each label says, keeps the subcutaneous reasoning clearly labelled as subcutaneous, states the one site-selection rule that does come from a testosterone label, and puts the schedules and distances nobody has published into the refusal ledger rather than inventing them.

What this page does not cover

These live elsewhere on the site and are not restated here.

• How to inject testosterone

  The sites themselves and everything about performing the injection: ventrogluteal and dorsogluteal landmarks, the thigh and the deltoid, needle choice, angle, the aspiration argument, bleeding, pain and sharps disposal. None of that is repeated here.

• Testosterone cypionate — compound page

  The vial-side administration checklist and the label’s own requirements before therapy, including inspecting the oil, swabbing the stopper and expelling air. This page starts after the syringe is filled.

• Injection schedule planner

  When the injections fall — dates and intervals for a prescribed regimen. This page is about where they go, and it deliberately does not generate a site calendar, for the reason set out in the ledger.

• Insulin syringe conversion chart

  Units against millilitres on every barrel, and the reason no page on this site prints a graduation interval as a fact.

The procedure

1. 1

   Start by finding out whether your own label says anything

   This is a real step rather than a formality, because for most testosterone products the answer is nothing. The reference testosterone cypionate label gives a route and a site and stops there — deep in the gluteal muscle, intramuscular only, not intravenously. There is no rotation instruction, no distance, no interval and no site map anywhere on it. Knowing that your label is silent is more useful than assuming it agrees with a diagram you found, because it tells you the instruction you are following came from somewhere else and lets you ask where.

   FDA label

   “DEPO-Testosterone Injection is for intramuscular use only. It should not be given intravenously. Intramuscular injections should be given deep in the gluteal muscle.”

   DEPO-Testosterone (testosterone cypionate injection, USP) — FDA label, Pharmacia & Upjohn, ANDA085635, via DailyMed. Read in full for this page: it names the gluteal muscle and contains no rotation instruction, no distance and no interval.
2. 2

   If you are on Aveed, the instruction is two sites, alternating

   The one testosterone label in the United States that tells you to change sites also tells you exactly how, and it is much simpler than the schemes in circulation: left buttock, then right buttock, then left. The same sentence in that label specifies the gluteus medius in the upper outer quadrant and warns about the superior gluteal arteries and the sciatic nerve, which is why this instruction belongs to a product given by a certified healthcare setting rather than at home. Note what it is not: it is not eight sites, it is not a quadrant grid, and it has no interval attached beyond "between consecutive injections".

   FDA label

   “The site for injection for AVEED is the gluteus medius muscle site located in the upper outer quadrant of the buttock. Care must be taken to avoid the needle hitting the superior gluteal arteries and sciatic nerve. Between consecutive injections, alternate the injection site between left and right buttock.”

   AVEED (testosterone undecanoate) injection — FDA prescribing information, Endo USA, Inc., via DailyMed. The only testosterone label in the United States that specifies alternating sites: left and right buttock, between consecutive injections.
3. 3

   If you are on a subcutaneous product, the labels do say rotate — every dose

   The GLP-1 and growth hormone labels are unambiguous and they attach the instruction to each individual injection rather than to a weekly or monthly pattern. Two of them add a refinement that people miss: you can stay in the same region and still be rotating, because the instruction is about the specific spot rather than the body part. Mounjaro’s instructions for use put it directly — you may use the same area of your body but must choose a different injection site within that area.

   FDA label

   “Change (rotate) your injection site with each injection. Do not use the same site for each injection.”

   OZEMPIC (semaglutide) injection — FDA prescribing information and Instructions for Use, Novo Nordisk, via DailyMed. Tells the patient to change the injection site with each injection and gives no reason for it anywhere on the label.
4. 4

   Know which problem your label is trying to prevent

   Only two of the seven labels give a reason, and both reasons are subcutaneous tissue problems. Mounjaro names lipodystrophy and localized cutaneous amyloidosis and describes what each looks like — pits or thickened skin, and skin with lumps. That is worth knowing for two opposite purposes. If you are on a subcutaneous product, these are the things you are inspecting for. If you are injecting an oil intramuscularly, these are lesions of the fat layer and nothing establishes that they are what you are at risk of.

   FDA label

   “Change (rotate) your injection site within the area you choose for each dose to reduce your risk of getting lipodystrophy (pits in skin or thickened skin) and localized cutaneous amyloidosis (skin with lumps) at the injection sites.”

   MOUNJARO (tirzepatide) injection — FDA prescribing information and Instructions for Use, Eli Lilly and Company, via DailyMed. The only label we read that names both lipodystrophy and localized cutaneous amyloidosis as the reasons for rotating, and describes what each looks like.
5. 5

   Treat one inch as the only distance anybody has written down

   People ask how far apart consecutive sites should be and the honest answer is that one document gives a number. Genotropin’s instructions for use say each new injection should be given at least one inch from the last, and its prescribing information gives the reason as preventing lipoatrophy. It is a growth hormone label and it is about a subcutaneous injection into the thigh, buttock or abdomen. Nothing comparable exists for an intramuscular oil injection, so this page prints the one inch with its provenance attached and does not generalise it.

   FDA label

   “GENOTROPIN may be given in the thigh, buttocks, or abdomen; the site of SC injections should be rotated daily to help prevent lipoatrophy.”

   GENOTROPIN (somatropin) — FDA prescribing information and Instructions for Use, Pfizer Laboratories Div Pfizer Inc, via DailyMed. The only label we read that states a distance between consecutive sites, and it gives lipoatrophy as the reason.
6. 6

   Never inject into skin that is already abnormal

   This is the one site-selection rule on the page that comes from a testosterone label rather than by analogy from insulin, and it is the most actionable thing here. Skip anything tender, bruised, red, scaly or hard, and avoid scars, tattoos and stretch marks. Note that "hard" covers the lump you have been injecting into for six months, which is exactly the tissue people default back to because it has stopped hurting. The insulin literature reaches the same instruction from the other direction — injections should not be given into a lipohypertrophic lesion.

   FDA label

   “Do not use in areas where the skin is tender, bruised, red, scaly, or hard. Avoid areas with scars, tattoos, or stretch marks.”

   XYOSTED (testosterone enanthate) injection — FDA prescribing information and Instructions for Use, Antares Pharma, Inc., via DailyMed. A subcutaneous testosterone product with no rotation instruction, and the source of the only site-selection rule on this page that comes from a testosterone label.
7. 7

   Look at the sites, and get someone else to look at them

   The single most transferable finding in the insulin literature is not about rotation patterns at all — it is that routine inspection of injection sites by a professional was associated with less lipohypertrophy, better glycaemic control and more correct rotation. Feel as well as look, because a thickened area is easier to find with a hand than with an eye, and check the sites you cannot see. Do this at a fixed point rather than when something already hurts, because the lesion that matters is the painless one you have stopped noticing.

   Published trial

   “Routine inspection of injection sites by the HCP was associated with lower glycated hemoglobin levels, less LH, and more correct injection site rotation.”

   Frid AH, Hirsch LJ, Menchior AR, Morel DR, Strauss KW. Worldwide Injection Technique Questionnaire Study: Injecting Complications and the Role of the Professional. Mayo Clin Proc. 2016;91(9):1224–1230. PMID 27594186 — 13,289 insulin-injecting patients in 42 countries. Corresponding author listed at Becton Dickinson.
8. 8

   Keep a written record, because memory is not a rotation system

   Nothing in any label instructs you to log injection sites and this step is here as practice rather than as instruction. The reason is practical: the failure mode of rotation is not choosing badly, it is defaulting to the side that is easier to reach and believing you alternated. A date, a side and a rough position takes five seconds, and it also gives you something to show whoever inspects the sites. What this page will not give you is a schedule to follow — see the ledger for why.

   Common practice — not established

   No label and no guideline we opened asks a patient to record injection sites. It is practice, and it is here because it makes the previous two steps possible rather than because anyone has shown it changes an outcome.

Which labels tell you to rotate, and what each one actually says

Seven FDA labels read in full on one question. The four subcutaneous products all say rotate. Of the three testosterone products, one specifies alternating between two sites, one names a site and says nothing further, and one never uses the word.

Read the route column against the third column and the pattern is complete: every product that gives a detailed rotation instruction is subcutaneous, and every reason any of them gives is a subcutaneous tissue problem — lipoatrophy, lipodystrophy, localized cutaneous amyloidosis, tissue atrophy. The one intramuscular testosterone product that addresses sites at all specifies a two-site alternation and nothing more elaborate. Nothing here supports the eight-site maps and clock-face diagrams circulated for intramuscular testosterone; that is not evidence they are wrong, it is evidence that nobody has written them down in a document anyone can check.

The reasons the labels give, and whether they can be carried over

Four named conditions and one named mechanism, with the tissue each occurs in. This is the table to read before assuming a subcutaneous instruction applies to an intramuscular oil.

Five "not established" cells and one yes. That is the honest state of the question, and it is worth stating what "not established" means here: nobody has shown that rotating an intramuscular oil injection prevents these things, and nobody has shown that it does not. What is established is the last row, and it comes from a testosterone label rather than by analogy — do not inject into skin that is tender, bruised, red, scaly or hard, or into scars, tattoos or stretch marks.

What the rotation evidence actually measured, and in whom

Every figure attached to injection site rotation in the sources we opened comes from one subject: insulin, in people with diabetes. The numbers are real and the population is not yours. Read the funding note in the footnote before quoting any of them.

Two things to attach to every figure above. The population is insulin users and the lesion is a subcutaneous one; none of it was measured in men injecting an oil-based testosterone ester intramuscularly, and this page does not transfer the numbers. And the provenance is worth naming, as this site does with any funded source: both the survey and the FITTER consensus workshop it fed list a corresponding author at a needle manufacturer. That does not make the 30.8% wrong — it was found by physical examination in a very large sample — but it is the kind of disclosure that belongs next to a figure rather than in a footnote nobody reads.

When it does not go to plan

What we could not source

Widely taught techniques we went looking for and could not anchor to a label, a public-health body or a trial. Each entry names what was searched and what this page does instead.

Frequently asked questions

Do you have to rotate testosterone injection sites?

Of the 7 FDA labels read in full for this page, exactly 1 testosterone product tells you to change sites, and it is narrower than people expect. AVEED: "Between consecutive injections, alternate the injection site between left and right buttock." 2 sites, alternating. The reference testosterone cypionate label says only that intramuscular injections "should be given deep in the gluteal muscle" and never mentions changing sites. The subcutaneous testosterone autoinjector specifies the abdomen and never uses the word rotate, though it does say not to inject into skin that is tender, bruised, red, scaly or hard. Silence in a label is not a prohibition — it means the question was not addressed, and whatever pattern you follow came from somewhere other than the product.

How far apart should injection sites be?

One inch, and only one document in this area says so. GENOTROPIN’s instructions for use state that each new injection should be given at least 1 inch from the site used before, and the prescribing information gives the reason as preventing lipoatrophy. That is a growth hormone label, for a subcutaneous injection into the thigh, buttock or abdomen. No label we read gives a distance for an intramuscular injection, and this page does not convert the subcutaneous figure into one. Where a reader expects a number for intramuscular testosterone, the answer is that it is not documented.

Why do GLP-1 labels tell you to rotate but testosterone labels do not?

Because they are preventing something specific to the tissue they inject into, and all 4 of the subcutaneous labels read for this page do it. MOUNJARO names the two conditions in its instructions for use — rotate within the chosen area each dose "to reduce your risk of getting lipodystrophy (pits in skin or thickened skin) and localized cutaneous amyloidosis (skin with lumps)". Both are lesions of skin and subcutaneous fat. The growth hormone labels name lipoatrophy and tissue atrophy, also subcutaneous. An intramuscular oil injection deposits below that layer, and nothing we opened establishes that it produces the same lesions. That is why the second table on this page prints "not established" five times rather than carrying the reasoning across.

What is the eight-site rotation schedule for TRT?

It does not appear in any document we could find. We read seven FDA labels in full plus the two main insulin injection-technique sources, and the most specific labelled instruction in existence is a two-site alternation on one product. No eight-site map, no clock-face diagram and no quadrant grid appears in any label, guideline or study we opened. This page prints none of them, not because they are necessarily bad practice but because reproducing a diagram with no provenance would make it look sourced. If your prescriber taught you one, that is a real instruction from someone who can examine you — which is more than any page can offer.

How common are lumps at injection sites?

The figures that exist are about insulin. The Worldwide Injection Technique Questionnaire study surveyed 13,289 insulin-injecting patients across 423 centres in 42 countries and found lipohypertrophy "self-reported by 29.0% of patients and found by physical examination in 30.8% by health care professionals". Patients with it used a mean of 10.1 IU more insulin daily and their HbA1c averaged 0.55% higher. None of that was measured in men injecting an oil-based testosterone ester, and this page does not transfer the numbers. Worth knowing about the provenance too: both that survey and the consensus workshop it fed list a corresponding author at a needle manufacturer.

Can I inject into the same spot if it does not hurt?

Painlessness is the wrong test, and the insulin literature is clear about why: lipohypertrophy is typically not painful, which is part of why people keep injecting into it. The rule that does come from a testosterone label is about what the tissue feels like rather than what it feels — do not use areas where the skin is "tender, bruised, red, scaly, or hard", and avoid scars, tattoos and stretch marks. "Hard" is the operative word for a site you have used for months. The most useful single habit in the insulin data was not a rotation pattern at all: routine inspection of the sites by a professional was associated with less lipohypertrophy and better control.

Sources

1. [1]DEPO-Testosterone (testosterone cypionate injection, USP) — FDA label, Pharmacia & Upjohn, ANDA085635, via DailyMed. Read in full for this page: it names the gluteal muscle and contains no rotation instruction, no distance and no interval.
2. [2]AVEED (testosterone undecanoate) injection — FDA prescribing information, Endo USA, Inc., via DailyMed. The only testosterone label in the United States that specifies alternating sites: left and right buttock, between consecutive injections.
3. [3]XYOSTED (testosterone enanthate) injection — FDA prescribing information and Instructions for Use, Antares Pharma, Inc., via DailyMed. A subcutaneous testosterone product with no rotation instruction, and the source of the only site-selection rule on this page that comes from a testosterone label.
4. [4]GENOTROPIN (somatropin) — FDA prescribing information and Instructions for Use, Pfizer Laboratories Div Pfizer Inc, via DailyMed. The only label we read that states a distance between consecutive sites, and it gives lipoatrophy as the reason.
5. [5]HUMATROPE (somatropin) — FDA prescribing information, Eli Lilly and Company, via DailyMed. Warnings and Precautions: repeated subcutaneous injection at the same site over a long period may cause tissue atrophy, and rotation reduces that risk.
6. [6]OZEMPIC (semaglutide) injection — FDA prescribing information and Instructions for Use, Novo Nordisk, via DailyMed. Tells the patient to change the injection site with each injection and gives no reason for it anywhere on the label.
7. [7]MOUNJARO (tirzepatide) injection — FDA prescribing information and Instructions for Use, Eli Lilly and Company, via DailyMed. The only label we read that names both lipodystrophy and localized cutaneous amyloidosis as the reasons for rotating, and describes what each looks like.
8. [8]Frid AH, Kreugel G, Grassi G, et al. New Insulin Delivery Recommendations. Mayo Clin Proc. 2016;91(9):1231–1255. PMID 27594187 — the FITTER consensus recommendations, written and vetted by 183 diabetes experts from 54 countries. Corresponding author listed at Becton Dickinson, a needle manufacturer.
9. [9]Frid AH, Hirsch LJ, Menchior AR, Morel DR, Strauss KW. Worldwide Injection Technique Questionnaire Study: Injecting Complications and the Role of the Professional. Mayo Clin Proc. 2016;91(9):1224–1230. PMID 27594186 — 13,289 insulin-injecting patients in 42 countries. Corresponding author listed at Becton Dickinson.