Subcutaneous vs intramuscular testosterone injections
Testosterone has traditionally been injected intramuscularly (IM), deep into a muscle. More and more people inject it subcutaneously (subQ), into the fat just under the skin, usually with a small insulin syringe. Here's what changes between the two.
Note: this is general information, not medical advice. Only switch how you inject with your prescriber's agreement, and use the technique you've been shown.
The practical differences
| Intramuscular (IM) | Subcutaneous (subQ) | |
|---|---|---|
| Where | Into a muscle: glute, ventrogluteal, thigh (quad), deltoid | Into the fat under the skin: belly, love handles, thigh |
| Needle | Longer, often 23–25 gauge, 25–38 mm | Short and fine, like an insulin syringe |
| Volume per injection | Can be larger, often up to 1 mL or more | Small, usually well under 1 mL |
| Typical schedule | Weekly or twice weekly | Often twice weekly, every other day or daily |
Small volumes are why subQ usually goes with more frequent, smaller doses. That also gives flatter levels: see weekly vs twice weekly vs daily.
What the research shows
- A 2017 study of 63 patients on weekly subcutaneous testosterone found all of them reached levels within or above the normal male range. Of the 22 who had used both methods, none preferred intramuscular, mainly because subQ was less painful and used smaller needles (Spratt et al., Journal of Clinical Endocrinology & Metabolism).
- A subcutaneous testosterone enanthate autoinjector (Xyosted) is approved in the US, which tells you regulators accept subQ testosterone as an effective route.
The studies are smaller than for IM, and individual responses vary, so a blood test after switching is the way to know your own levels.
Things people notice with subQ
- Less pain and less anxiety about needles.
- Small lumps or redness at the site, which usually settle. One that's hot, spreading or painful needs to be checked.
- Thicker oils can be slow to push through a fine needle. Warming the vial in your hand helps.
Rotate either way
Whichever you use, rotating sites gives each spot time to recover. See injection site rotation.
Switching
If you and your prescriber decide to switch, keep a note of the date. Levels take a few weeks to settle on any new schedule (about five half-lives), so a blood test 4–6 weeks after the change shows where you've landed.
General information, not medical advice. Your prescriber sets your dose and schedule.
Track it without the spreadsheet
Enhanced Training Studio schedules every injection, shows what to draw, rotates your sites and estimates your levels. The protocol tracker is free, needs no account and keeps everything on your phone.
See the TRT tracker Levels calculator