Subcutaneous (under the skin) and intramuscular (into the muscle) testosterone injections both raise testosterone into the normal range effectively, and research comparing the two has found no meaningful difference in how well they work. The real differences are practical: subcutaneous shots use a shorter, thinner needle and tend to hurt less, while intramuscular injections have a longer track record and are still what most clinics default to.
What's the actual difference between the two injection methods?
Intramuscular (IM) injections push testosterone cypionate or enanthate deep into muscle tissue, usually the glute or the outer thigh, using a needle that's typically 1 to 1.5 inches long. Subcutaneous (SubQ or SC) injections deposit the same medication into the fat layer just under the skin, most often in the abdomen or the front of the thigh, using a much shorter needle, often around 1/2 inch, and a finer gauge. Muscle tissue absorbs medication faster than fat does, which is the underlying reason the two routes are sometimes dosed and scheduled slightly differently, even though the drug itself is identical.
Does subcutaneous testosterone work as well as intramuscular?
Yes. A study following 63 transgender men who switched from intramuscular to subcutaneous testosterone cypionate or enanthate found that all patients reached normal-range testosterone levels on the subcutaneous route, across a wide range of body weights, using injection amounts similar to what they'd needed intramuscularly (Spratt et al., Journal of Clinical Endocrinology & Metabolism, 2017). A related analysis from the same research group found that subcutaneous testosterone levels stayed more stable between doses, with less of the sharp peak-and-trough pattern that intramuscular injections can produce (Journal of the Endocrine Society, 2017). In practice, that steadier curve is why some men on subcutaneous dosing report fewer of the mood or energy dips that can show up in the days before an intramuscular shot is due.
Which one hurts less?
Subcutaneous injections are generally reported as less painful, largely because the needle is shorter and thinner and doesn't have to pass through muscle. Fat tissue also has fewer nerve endings than muscle in the areas typically used for injection. That said, pain tolerance varies, and some men find IM injections into a relaxed, warm muscle to be just as tolerable, especially once they've built up technique and comfort with the process.
Is one method safer than the other?
Both are considered safe when done with proper technique, but they carry slightly different risk profiles. IM injections carry a small risk of hitting a blood vessel or nerve if the injection site is chosen poorly, which is why the upper-outer glute and the vastus lateralis (outer thigh) are the standard sites. Subcutaneous injections carry a lower risk of that kind of injury but a slightly higher chance of visible bruising or small lumps at the injection site since the medication sits closer to the skin. The one subcutaneous product with its own FDA boxed warning is Xyosted, a weekly auto-injector pen: its label warns that testosterone enanthate delivered this way can raise blood pressure enough to increase the risk of heart attack, stroke, and cardiovascular death in some patients, and it also carries a warning about new or worsening depression and suicidal thoughts, so blood pressure and mood need to be monitored on that specific product regardless of route (FDA prescribing information, 2025). That warning is specific to Xyosted's dosing schedule and formulation, not a blanket statement about all subcutaneous testosterone.
How do dosing and frequency compare?
Because subcutaneous absorption is slower and steadier, some prescribers split the weekly dose into smaller, more frequent subcutaneous injections, such as twice a week instead of once, to keep levels even flatter. Intramuscular dosing is more commonly done once a week or once every two weeks at a slightly higher dose per shot. Neither schedule is inherently superior. What matters most is which pattern keeps your bloodwork in range and your symptoms controlled, which is something your prescriber should be checking with follow-up labs rather than assuming from the injection method alone.
