Is Subcutaneous Testosterone as Effective as Intramuscular?
Yes, for weekly testosterone cypionate or enanthate. Studies that compared the two routes found that a shot into the fat under the skin raises testosterone about as much as a shot into the muscle at a similar dose, and most people find it less painful. The evidence comes from small studies and one larger comparison, not a big randomized trial.
Subcutaneous (often shortened to “subq” or “SC”) means the needle goes into the fat layer just under the skin, usually on the belly or thigh. Intramuscular (“IM”) means a longer needle goes deep into a muscle, such as the buttock or outer thigh. Both deliver the same hormone, testosterone, dissolved in oil.
What the Data Show
A systematic review from Brigham and Women’s Hospital pulled together the trials, case series and case reports on subcutaneous testosterone. It concluded that the evidence, though limited, suggests subcutaneous doses similar to intramuscular doses give comparable testosterone levels in the blood. It also found that subcutaneous shots are easier to give yourself and cause less discomfort.
The closest thing to a head-to-head test is a crossover study of 14 transgender men who were already on intramuscular testosterone. They injected intramuscularly for 3 weeks, then switched to subcutaneous injections for 8 weeks. Total testosterone exposure over the week was about the same with both routes, though levels varied a lot from person to person.
The largest comparison included 234 men with low testosterone. One group got 100 mg of intramuscular testosterone cypionate each week and the other got 100 mg of subcutaneous testosterone enanthate by autoinjector each week. After 12 weeks, average trough levels (the lowest point, just before the next dose) rose from 314 to 536 ng/dL in the intramuscular group and from 247 to 553 ng/dL in the subcutaneous group. After adjusting for other factors, the route was not linked to the final testosterone level.
The study this page was first written about was a review of 63 transgender men treated with weekly subcutaneous testosterone at one clinic. Every one of them reached testosterone in the normal male range, on doses of 50 to 150 mg a week. It worked across a body mass index range of 19.0 to 49.9.
In a prospective study of 26 transgender teenagers, trough testosterone levels were similar with subcutaneous and intramuscular shots by 6 months, and body changes and quality of life did not differ between the groups.
Does Subq Testosterone Work for Men With Low T?
Yes. Much of the early research was done in transgender men, but the FDA approval studies were done in men with hypogonadism (low testosterone from the testes or the brain signals that drive them).
In a 52-week study of 150 men with low testosterone, the men gave themselves a weekly subcutaneous shot of testosterone enanthate with an autoinjector, starting at 75 mg and adjusted to 50, 75 or 100 mg. At week 12, 92.7% had an average testosterone level between 300 and 1,100 ng/dL. No one went above 1,800 ng/dL at week 12, and the average trough level was still 487 ng/dL at one year.
A 26-week study of 133 men using the same device found trough levels between 300 and 650 ng/dL in about 83% of men at weeks 12 and 26.
An earlier phase II study of 39 men with hypogonadism randomized them to 50 or 100 mg of subcutaneous enanthate weekly. Average steady levels were 422 and 896 ng/dL, and levels rose in step with the dose.
These were single-group studies run with the drug maker, not trials that randomly assigned men to subcutaneous or intramuscular shots. Still, the results match the transgender studies closely.
Are Testosterone Levels More Stable With Subq Injections?
Weekly subcutaneous shots tend to give a flatter curve. In a study that drew blood 8 times across one week in 11 patients on weekly subcutaneous cypionate, average total and free testosterone stayed stable and well within the normal range between injections.
The 52-week autoinjector study also reported a steady testosterone profile with small peaks and troughs. In the teenage comparison study, peak levels at 3 months were higher in the intramuscular group.
Part of the difference may come from how often people inject. Weekly dosing, whatever the route, gives smaller swings than a large shot every 2 weeks.
Is Subcutaneous Testosterone Less Painful? Is It Easier for Beginners?
For most people, yes. In the 14-person crossover study, subcutaneous shots scored lower for anxiety before the injection, pain during it, and pain afterward.
Among the 22 patients in the 63-person clinic review who switched from intramuscular to subcutaneous, all 22 preferred subcutaneous, 20 of them strongly. None wanted to go back.
In the 52-week autoinjector study, more than 95% of men reported no injection pain. In the 26-week study, mild pain was reported by just 1 man across 965 injections.
Self-injection is the practical win. In the teenage study, 92% of participants were giving their own shots by 3 months, and the teenagers expressed a preference for both injection types.
The needle is shorter and thinner, and the belly is easy to reach. That matters for people who would otherwise need a clinic visit or a partner to give a shot into the buttock.
One exception: testosterone undecanoate. This long-acting form is given as a large 4 mL shot every few months. In a randomized crossover study of 20 long-term users, the subcutaneous shot hurt more 24 hours later, and 11 preferred intramuscular while 6 preferred subcutaneous. Testosterone levels did not differ by route.
Side Effects: Hematocrit, Estradiol and Injection Site Reactions
Hematocrit is the share of your blood made up of red cells. Testosterone raises it, and a level that climbs too high thickens the blood. A systematic review of 18 studies in transgender men concluded that every testosterone formulation raises hematocrit, whatever the dose, form or route. Subcutaneous shots do not avoid this.
There may be a difference in degree. In the 234-man comparison, the subcutaneous autoinjector group had lower hematocrit and lower estradiol (the main estrogen) after 12 weeks than the intramuscular cypionate group. That study was not randomized and compared two different testosterone esters, so it does not prove the route alone made the difference.
In the 26-week autoinjector study, hematocrit reached 52% or higher in 10 of 133 men (7.5%). Clinic systolic blood pressure rose by an average of 3.4 mmHg. In the 52-week study, high hematocrit, high blood pressure and rising PSA were the most common side effects, and they led 30 men to stop.
Skin reactions are the trade-off. In the teenage study, mild skin reactions happened in 12% of participants, all in the subcutaneous group. In the clinic review, 9 of 63 had minor, short-lived reactions at the injection site. Bruising and small bleeds at the site were the common injection problems in the 26-week study.
Can You Inject Testosterone Cypionate Subcutaneously?
Yes, and it has been studied. Testosterone cypionate and enanthate are the same hormone attached to slightly different chains, and both are dissolved in oil. The 63-patient clinic review used either one subcutaneously, and the stable-levels study used cypionate.
In the US, the subcutaneous autoinjector of enanthate (Xyosted) is labeled for that route. Using a vial of cypionate under the skin is a common practice, but it falls outside the cypionate label, so it is a decision to make with the prescribing clinician.
| Subcutaneous (subq) | Intramuscular (IM) | |
|---|---|---|
| Needle | Short and thin, into belly or thigh fat | Longer, deep into muscle |
| Testosterone levels | About the same at similar weekly doses | About the same |
| Swings between doses | Small with weekly dosing | Higher peaks in one comparison |
| Pain | Lower in the studies | Higher |
| Skin reactions | More common, mostly mild | Less common |
| Hematocrit | Still rises; lower in one 234-man comparison | Rises |
Dr. Kumar’s Take
The deep muscle shot became the default because it was the first way testosterone was given, not because anyone proved it worked better. When researchers looked, the shot under the skin raised levels about as well and hurt less. For a treatment many people stay on for years, a shot you can give yourself at home in a few seconds is a real advantage.
What subcutaneous injection does not change is the monitoring. Testosterone still raises red blood cell counts, and blood pressure and PSA still need checking. The route makes therapy easier to live with. It does not make it a different drug.
Practical Takeaways
- Subq works. Weekly subcutaneous cypionate or enanthate reached normal levels in the studies, at doses similar to intramuscular.
- Expect less pain. Most people who tried both routes preferred subcutaneous.
- Weekly dosing gives steadier levels than larger, less frequent shots.
- Rotate injection sites on the belly or thigh to limit bruising and redness.
- Keep checking blood work. Hematocrit, blood pressure and PSA still rise on subcutaneous testosterone.
- Undecanoate is different. The long-acting 4 mL shot hurt more under the skin.
- Talk to your prescriber before switching, because dose and timing may need adjusting to your blood levels.
Related Studies and Research
- Podcast: Testosterone Replacement Therapy Explained
- Muscular Responses to Testosterone Therapy Differ by Administration Route
- Defining Normal Testosterone: Harmonized Reference Ranges Across Populations
- Testosterone Therapy Modestly Improves Libido and Erections in Men With Low Testosterone
- Is Testosterone Safe for Men After Prostate Cancer Surgery?
- One Week of Sleep Restriction Reduces Testosterone by 10% to 15% in Young Men
FAQs
Is subq testosterone as effective as IM?
In the studies so far, yes. Similar weekly doses gave similar testosterone levels by either route. The evidence comes mostly from small studies and one 234-man comparison, not a large randomized trial.
Does subcutaneous testosterone need a higher dose?
Not in the research. A systematic review found that doses similar to intramuscular doses gave comparable blood levels. The dose is set by your blood levels either way.
Is subq testosterone easier for beginners who are nervous about needles?
Usually. The needle is shorter and thinner, and people in the studies reported less anxiety and less pain with subcutaneous shots. Most beginners in the teenage study were injecting themselves within 3 months.
Where do you inject subcutaneous testosterone?
The fatty tissue of the belly or thigh is the usual site. Moving the spot each week helps limit bruising and redness.
Does subq testosterone raise hematocrit less?
It still raises hematocrit, like every form of testosterone. One comparison found lower hematocrit with a subcutaneous autoinjector than with intramuscular cypionate, but that study was not randomized and used two different forms of testosterone.
Bottom Line
Subcutaneous testosterone raises levels about as well as intramuscular shots at similar weekly doses, and most people find it less painful and easier to do at home. It causes more minor skin reactions and still raises red blood cell counts, so the same blood work applies. The long-acting undecanoate shot is the exception, where intramuscular was better tolerated.
