Where to Inject Testosterone? Common & Safe Sites

Testosterone is most commonly injected into large muscles of the thigh or glute for intramuscular delivery, or into the fat layer of the abdomen or outer thigh for subcutaneous delivery. Both routes produce comparable blood levels of testosterone, and the choice between them often comes down to needle comfort, injection volume, and what your prescriber recommends. The specifics of each site, and the practical differences between them, matter more than most people realize when they first start injections.

Intramuscular Sites

Intramuscular injections deposit testosterone deep into muscle tissue, where the oil-based solution forms a small depot that absorbs gradually into the bloodstream. The most widely used intramuscular sites for testosterone are the vastus lateralis (the outer middle portion of your thigh), the ventrogluteal site (the upper-outer hip area), and the dorsogluteal site (the upper-outer quadrant of the buttock). The deltoid muscle of the upper arm is sometimes used for smaller-volume injections, but it is generally less practical for the typical testosterone dose volume.

The thigh is popular for self-injection because you can see and reach it easily while sitting. You inject into the outer middle third of the thigh, roughly a hand’s width above the knee and a hand’s width below the hip, staying on the outer or slightly front side of the leg. The muscle there is large enough to absorb a standard injection without much discomfort.

The ventrogluteal site, on the side of the hip, has gained favor among clinicians over the traditional dorsogluteal (upper buttock) site. A study comparing the two in older adults found that while both sites met safety thresholds for intramuscular injection, the ventrogluteal site had greater muscle thickness and thinner subcutaneous tissue, which means the needle is more likely to reach muscle and less likely to accidentally deposit medication into fat or contact bone.¹ The ventrogluteal site also avoids the sciatic nerve and major blood vessels that run through the buttock, making it the safer bet for most people. The trade-off is that it can be harder to locate on your own body without practice, and self-injecting there requires some flexibility.

The dorsogluteal site remains in wide use, particularly for larger-volume injections like testosterone undecanoate, which requires a full 4 mL. Guidelines for that formulation call for slow, deep injection into the gluteal muscle, ideally with the patient lying face down.² The prone position relaxes the muscle and helps ensure the needle reaches deep enough. Because the dorsogluteal site is hard to reach on your own, it is usually administered by a healthcare provider or a trained helper.

Subcutaneous Sites

Subcutaneous injection places testosterone into the layer of fat just below the skin rather than into muscle. The two standard subcutaneous sites are the abdomen and the outer thigh. For abdominal injections, you inject roughly two to three finger-widths to the side of the belly button, pinching a fold of skin and inserting the needle at about a 45-degree angle.³ For the thigh, you pinch a fold of fat on the front or outer surface of the upper leg and inject at the same angle.

One reason the subcutaneous route has grown in popularity is the needle. Where intramuscular injections use needles that are typically 1 to 1.5 inches long, subcutaneous injections use a much shorter needle, usually five-eighths of an inch, with a finer gauge.³ That difference is immediately noticeable to anyone who has dreaded the longer intramuscular needle. The smaller needle also makes the injection easier to learn and perform at home.

Subcutaneous sites are not appropriate for all testosterone formulations, though. Testosterone cypionate and testosterone enanthate, the two most commonly prescribed esters, work well subcutaneously at standard weekly or biweekly doses. Testosterone undecanoate, which comes in a much larger volume, has limited published data for the subcutaneous route, though some clinicians have administered it into abdominal fat using a slightly larger needle and a slower injection speed.³ If you are on testosterone undecanoate, your provider will likely stick with intramuscular administration unless they have specific experience doing otherwise.

How Subcutaneous Compares to Intramuscular

The question most people have when they first hear about subcutaneous testosterone is whether it actually works as well. The short answer is yes, for the standard esters. A pilot study comparing the two routes found that total testosterone exposure was comparable between subcutaneous and intramuscular injection, with no statistically significant difference.⁴ A broader review of the available evidence reached the same conclusion: subcutaneous doses similar to those used intramuscularly produce comparable average serum testosterone levels.³ There is some variability from person to person and injection to injection, but that is true of intramuscular delivery too.

Patient preference leans heavily toward subcutaneous. In the pilot study, self-reported scores for anxiety before injection, pain during injection, and pain afterward were all lower with the subcutaneous route.⁴ A separate study surveyed patients who had switched from intramuscular to subcutaneous injections and found that every single participant preferred the subcutaneous route, with the vast majority expressing a strong preference rather than a mild one.⁵ None preferred going back to intramuscular.

The subcutaneous route is not without downsides. Some patients in that same study reported small nodules at the injection site that came and went over a day or two, and a couple experienced mild hives near the injection site that lasted a few days.⁵ One patient had a single episode of local skin infection that resolved on its own. These reactions were infrequent and generally mild, but they are worth knowing about so you do not panic if a small bump appears after an injection.

Needles and Equipment

The needle you use depends entirely on whether you are injecting into muscle or into fat. For subcutaneous injection of testosterone cypionate or enanthate, the standard setup is a 1 mL Luer-Lok syringe with a 25-gauge, five-eighths-inch needle.³ The Luer-Lok design means the needle screws onto the syringe rather than just pressing on, which prevents it from popping off when you push the plunger against the thick, viscous oil. Some clinicians use a 23-gauge needle without difficulty for both short-acting and long-acting testosterone esters.³ An autoinjector device designed for subcutaneous testosterone enanthate uses an even finer 27-gauge needle, though that device is not universally available.⁶

For intramuscular injections, needles are longer and slightly thicker. A 22- or 23-gauge needle of 1 to 1.5 inches is typical for the thigh or glute. Many people use a two-needle technique: draw the testosterone out of the vial with a larger-gauge needle (18 or 20 gauge) to speed up the process, then swap to a fresh, thinner needle for the actual injection. This keeps the injection needle sharp, since pushing it through a rubber vial stopper dulls the tip slightly. Using a fresh needle for injection also reduces the amount of oil that leaks along the needle track.

For testosterone undecanoate, which comes in a large 4 mL ampoule, a 21-gauge needle is typically used. The injection should be given slowly, over at least one to two minutes, to reduce local irritation.²

Technique Tips for Less Pain

Good technique makes a real difference in how comfortable your injections feel. For intramuscular injections, the Z-track method is a widely taught approach. You use your non-dominant hand to pull the skin at the injection site a couple of centimeters to one side, insert the needle, inject, then release the skin after withdrawing. The displaced tissue layers close off the needle track, which reduces leakage of the medication back out through the skin. A study testing this technique found that it reduced the amount of drug leakage compared to standard injection, though it did not significantly reduce pain during the injection itself.⁷ A systematic review confirmed this pattern: the Z-track method helps with leakage but its benefit for pain is not clearly established.⁸

Other practical tips that help across both routes: relax the muscle before injecting by finding a comfortable, supported position. If you are injecting your thigh intramuscularly, sit with your leg relaxed and slightly bent. Warm the testosterone vial in your hands or under warm water for a minute before drawing it up, as slightly warmer oil flows more easily through the needle and deposits into tissue more smoothly. Inject at a steady, moderate pace rather than pushing the plunger quickly. And do not recap the needle with two hands after use, which is a common source of accidental needle sticks.

Why Site Rotation Matters

If you inject in the same spot every time, the tissue can develop lumps, scar tissue, or chronic irritation. This is true for both intramuscular and subcutaneous injections. With subcutaneous delivery, repeated injections in the same spot can cause small nodules or areas of hardened fat. With intramuscular delivery, the muscle can develop fibrotic areas that make future injections more painful and less effective at absorbing the drug.

People experienced with long-term injectable therapy have developed their own rotation systems, alternating between left and right sides and cycling through multiple sites to give each area time to recover between injections.⁹ A simple rotation for someone injecting weekly might be: right thigh, left thigh, right abdomen, left abdomen, then repeat. For intramuscular injectors, alternating between the right and left vastus lateralis, or cycling between a thigh and a glute, works well. The key principle is to avoid hitting the same patch of tissue within at least a couple of weeks.

Complications Worth Knowing About

Most testosterone injections are uneventful, but a few complications come up often enough to be aware of. Local site reactions are the most common: soreness, a small bump, mild redness, or a bruise at the injection site. These typically resolve within a few days and are more of an annoyance than a medical concern. Injecting too quickly or using a dull needle tends to make local irritation worse.

Pulmonary oil microembolism, often shortened to POME, is a rare complication specific to oil-based intramuscular injections, particularly testosterone undecanoate. It happens when a small amount of the oily solution enters a blood vessel and travels to the lungs, causing symptoms like coughing, chest tightness, or shortness of breath. A literature review covering nearly 8,000 patients across 29 studies found that POME cases were uncommon, and a post-market analysis reported roughly 223 cases out of over three million injections.¹⁰ When POME does happen, it almost always resolves on its own within about an hour. A post-marketing safety analysis found that in the majority of serious POME cases, problems with injection technique or dosing were identified as contributing factors.¹¹ This is one reason testosterone undecanoate is typically administered in a clinical setting rather than at home.

In extremely rare cases, accidental injection directly into a blood vessel can cause acute respiratory distress. A case report described a bodybuilder who accidentally injected an oil-steroid solution intravenously and developed immediate breathing difficulty and low oxygen levels. Chest imaging showed widespread opacities in both lungs, but the symptoms improved over 48 hours and the imaging was normal a week later.¹² This kind of event is vanishingly rare with proper technique and site selection. Choosing sites with fewer large blood vessels (like the ventrogluteal area or the outer thigh rather than the inner thigh) reduces the risk further.

Infection at the injection site is possible but uncommon with good hygiene. Cleaning the skin with an alcohol swab, using a sterile needle each time, and washing your hands thoroughly before handling supplies are the non-negotiable basics. If a site becomes increasingly red, swollen, warm, or painful over the days after an injection, or if you develop a fever, see a provider. Caught early, a local infection is straightforward to treat.

Learning to Self-Inject

Starting testosterone injections can feel intimidating, and the learning curve is real but short. Training matters. A usability study of a subcutaneous autoinjector found that participants who received training beforehand had an injection success rate above 90%, compared to about 80% for untrained participants.¹³ Untrained participants made about twice as many errors on their first attempt. Interestingly, the study also found that patients, caregivers, and people with no injection experience at all had broadly similar success rates once they had basic instruction, with success hovering around 85% for everyone.¹³ So if you are a complete beginner, you are not at a meaningful disadvantage compared to someone who has injected other medications before. What matters is that you get proper instruction first.

That instruction does not necessarily have to happen in a clinic. A study comparing telehealth injection teaching to in-person training for people starting gender-affirming testosterone therapy found no significant difference in testosterone levels at three and six months between the two groups.¹⁴ The telehealth group contacted their clinic slightly more often afterward, but the number of injection-specific questions was similarly low in both groups. If getting to an in-person appointment is a barrier, a video training session with your provider can work just as well for learning technique.

Choosing Between Sites in Practice

Your prescriber will likely recommend a specific route and site based on your formulation, dose volume, and comfort level, but here is a practical way to think about the trade-offs. If you are on testosterone cypionate or enanthate at a standard weekly or biweekly dose, you have the most flexibility. The subcutaneous route into the abdomen or thigh is the easiest to learn, uses the smallest needle, and is overwhelmingly preferred by patients who have tried both. If you have very little body fat, subcutaneous injection can be trickier because there is less tissue to pinch, and your provider may suggest intramuscular instead.

For intramuscular self-injection, the outer thigh is the most practical starting point because you can see what you are doing and reach it comfortably. The ventrogluteal site is a strong alternative once you or your provider identify the landmarks, and it has a better safety profile than the traditional upper-buttock injection. The dorsogluteal site is best reserved for situations where someone else is administering the injection, since reaching your own upper buttock while also controlling the needle is awkward and increases the chance of poor placement.

If you are on testosterone undecanoate, the decision is mostly made for you. The large injection volume and the POME risk associated with intramuscular oil depots mean this is administered by a healthcare provider, usually into the gluteal muscle, with a monitoring period afterward. The local discomfort from the 4 mL volume is mild for most people and typically fades within a few days when the injection is given slowly.²

Whatever site and route you start with, expect the first few injections to be the hardest psychologically. The actual physical discomfort is usually less than people fear, and it diminishes as you get more practiced. Keeping a simple log of which site you used and which side of the body you injected can help you maintain a good rotation pattern without having to remember from week to week.

1
PubMed. Examining the Safety of Dorsogluteal and Ventrogluteal Sites for Intramuscular Injection in Older Adults
2
Clinical Interventions in Aging. Testosterone depot injection in male hypogonadism: a critical appraisal
3
PubMed Central. Testosterone Therapy With Subcutaneous Injections: A Safe, Practical, and Reasonable Option
4
American Journal of Health-System Pharmacy. Pharmacokinetics, safety, and patient acceptability of subcutaneous versus intramuscular testosterone injection for gender-affirming therapy
5
The Journal of Clinical Endocrinology & Metabolism. Subcutaneous Injection of Testosterone Is an Effective and Preferred Alternative to Intramuscular Injection
6
Sexual Medicine. Pharmacokinetic Profile of Subcutaneous Testosterone Enanthate Delivered via a Novel, Prefilled Single‐Use Autoinjector
7
PubMed. The Effect of the Z-Track Technique on Pain and Drug Leakage in Intramuscular Injections
8
PLOS ONE. The effect of intramuscular injection technique on injection associated pain; a systematic review and meta-analysis
9
PubMed Central. Creating Safer Injecting Practices Through Community-Led Harm Reduction
10
International Journal of Impotence Research. Occurrence of pulmonary oil microembolism (POME) with intramuscular testosterone undecanoate injection
11
PubMed Central. Occurrence of Pulmonary Oil Microembolism After Testosterone Undecanoate Injection
12
PubMed Central. Acute respiratory distress following intravenous injection of an oil-steroid solution
13
The Journal of Sexual Medicine. Summative Usability Evaluation of the SCTE-AI Device
14
PubMed Central. Telehealth Versus In-Person Injection Instruction for Adolescents and Young Adults Initiating Gender-Affirming Testosterone Therapy