Subcutaneous vs. Intramuscular Testosterone: What theResearch Actually Shows

Subcutaneous vs. Intramuscular Testosterone: What

the Research Actually Shows

If you’ve started looking into testosterone replacement therapy (TRT), you’ve probably

pictured the same thing most men do: a long needle, a deep muscle injection, and a little bit

of dread every week. That image keeps a lot of men from ever starting treatment — even

when they’re exhausted, foggy, and not feeling like themselves.

Here’s the good news. You don’t have to choose between feeling better and feeling anxious

about your injections. A growing body of peer-reviewed research shows that subcutaneous

(SubQ) testosterone injections — the kind delivered with a short, thin needle just under

the skin — work just as well as traditional intramuscular (IM) injections, often with a

smoother experience and fewer side effects. At Next Phase of Health, this is one of the

reasons we favor SubQ dosing for so many of our patients: it’s not a compromise, it’s

backed by the science.

Why the Injection Method Matters More Than You’d Think

Testosterone therapy has traditionally meant IM injections — deep into the glute or thigh,

often every one to two weeks. It works, and for decades it was the only well-studied option.

But “how it’s always been done” and “what the evidence supports” aren’t always the same

thing.

When testosterone is injected into muscle tissue, it’s absorbed through a dense network of

blood vessels, which tends to create sharp peaks in testosterone right after the injection

followed by a steep decline before the next dose. Many men feel that swing — energy and

mood spike, then crash as levels fall. SubQ injections, delivered into the fatty tissue beneath

the skin, are absorbed more gradually through the lymphatic system, which tends to

produce steadier, more consistent hormone levels between doses.

What the Peer-Reviewed Research Says

This isn’t a theory — it’s been studied directly in men with low testosterone

(hypogonadism).

• Kaminetsky et al. (2015, Sexual Medicine) studied men with hypogonadism receiving

weekly subcutaneous testosterone enanthate through an autoinjector and found it

restored testosterone to the normal range with steady, predictable, dose-proportional

levels and good tolerability, comparable to standard intramuscular dosing.

• Spratt et al. (2017, Journal of Clinical Endocrinology & Metabolism) directly

compared the two delivery routes and concluded that subcutaneous testosterone is an

effective and often preferred alternative to intramuscular injection, with less discomfort

reported by patients.

• A follow-up pharmacokinetic study (2017, Journal of the Endocrine Society)

measured testosterone levels between weekly subcutaneous doses and found levels

remained notably stable from one injection to the next — direct evidence against the

peak-and-crash pattern many men experience on IM therapy.

• A larger clinical comparison published in the Journal of Urology (2021) followed 234

hypogonadal men treated with either intramuscular testosterone cypionate or

subcutaneous testosterone enanthate. The men on subcutaneous therapy showed

significantly smaller rises in estradiol, hematocrit, and PSA compared to the

intramuscular group — all markers we monitor closely to keep TRT safe long-term.

• A 52-week registration study of a subcutaneous testosterone enanthate autoinjector in

hypogonadal men found that the vast majority of patients achieved and maintained

target testosterone levels over a full year of treatment, with a well-tolerated safety

profile.

Taken together, this research tells a consistent story: subcutaneous testosterone isn’t a

shortcut or a lesser option. For many men, it’s a more physiologically stable way to restore

healthy testosterone levels — with real advantages for comfort and long-term safety

monitoring.

Why This Matters for You

We hear it constantly in our clinic: men who’ve been quietly struggling with low energy, low

libido, brain fog, or a mood that just isn’t theirs anymore — and who put off treatment for

months or years because the idea of injections felt intimidating.

You don’t have to white-knuckle your way through a big IM needle to get your testosterone

back where it belongs. SubQ testosterone typically uses a much smaller, thinner needle, can

be self-administered comfortably at home, and — based on the research above — offers

steadier hormone levels with a favorable safety profile.

You also don’t have to figure this out on your own. Low testosterone is common, it’s

treatable, and safe treatment starts with a provider who checks your labs, watches your

estradiol and hematocrit, and adjusts your plan as your body responds — not a one-size-

fits-all prescription.

Getting Started Safely

At Next Phase of Health, every TRT plan starts with a full hormone and metabolic workup,

not just a testosterone number. From there, we build a protocol — often using subcutaneous

dosing — designed around your labs, your symptoms, and your goals, with ongoing

monitoring to keep things safe as your levels stabilize.

If you’ve been putting off asking for help, consider this your sign. You don’t have to suffer

through low T, and you don’t have to be afraid of the needle to get your life back.

Ready to find out if TRT is right for you? Schedule a consultation with our team in

Glenview, IL, or call us at 847-393-9591.

References

1. Kaminetsky J, Jaffe JS, Swerdloff RS. Pharmacokinetic Profile of Subcutaneous

Testosterone Enanthate Delivered via a Novel, Prefilled Single-Use Autoinjector: A Phase

II Study. Sex Med. 2015;3:263-273.

2. 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.

3. McFarland J, Craig W, Clarke NJ, Spratt DI. Serum Testosterone Concentrations Remain

Stable Between Injections in Patients Receiving Subcutaneous Testosterone. J Endocr

Soc. 2017;1(8):1095-1103.

4. Comparison of Outcomes for Hypogonadal Men Treated with Intramuscular

Testosterone Cypionate versus Subcutaneous Testosterone Enanthate. J Urol. 2021.

5. A 52-Week Study of Dose Adjusted Subcutaneous Testosterone Enanthate in Oil Self-

Administered via Disposable Auto-Injector. 2018.

This article is for educational purposes and is not a substitute for individualized medical

advice. Talk with a licensed provider before starting or changing any hormone therapy.