Testosterone injections go into either muscle tissue or the fat layer just beneath the skin, depending on the method your provider prescribes. The most common intramuscular sites are the outer thigh and the hip, while subcutaneous injections typically go into the belly fat or the fatty tissue on the front of the thigh. Each site has distinct advantages, and knowing exactly where to place the needle matters for both safety and comfort.
Intramuscular Injection Sites
Intramuscular (IM) injections deliver testosterone deep into muscle, where it absorbs into the bloodstream over days. Two sites are used most often for self-injection.
Outer Thigh (Vastus Lateralis)
The outer thigh is the most popular site for people injecting themselves because it’s easy to see and reach. The safe zone is the middle third of the outer thigh, roughly halfway between the bony prominence at the top of your hip (the greater trochanter) and your knee. A cross-sectional study on adults and cadavers published in Human Vaccines & Immunotherapeutics confirmed that this midpoint is free of major blood vessels and nerves, making it the lowest-risk location on the thigh.
To find it, sit down and look at the outer surface of your thigh. Mentally divide the distance from hip to knee into three equal sections. Your target is the middle section, on the outer side of the leg, not the top or the inner surface. Injecting too far forward or too close to the knee increases the chance of hitting a nerve branch or a deeper artery that runs along the border between the front and outer thigh muscles.
Hip (Ventrogluteal)
The ventrogluteal site sits on the side of the hip, over the gluteus medius muscle. It’s the site most nursing guidelines now recommend over the traditional upper-outer buttock (dorsogluteal). The American Academy of Ambulatory Care Nursing notes that, unlike the dorsogluteal area, the ventrogluteal site is free from major nerves and blood vessels, has a thinner layer of fat, and tends to be less painful.
To locate it, place the heel of your opposite hand on the bony prominence at the front of the hip (the greater trochanter). Point your index finger toward the front of the hip bone and spread your middle finger back toward the curve of the buttock. The triangle formed between those two fingers is your injection zone. This site works well but is harder to reach on your own, so some people prefer having a partner help or simply default to the thigh.
Deltoid (Shoulder)
The deltoid muscle on the upper arm is sometimes used for smaller-volume IM injections, but it holds less fluid than the thigh or hip. For testosterone doses of 1 mL or more, the thigh and hip are better choices because the deltoid can only comfortably absorb about 1 mL at a time. The deltoid also requires a shorter needle and more precise placement to avoid the nerve that wraps around the upper arm bone.
Subcutaneous Injection Sites
Subcutaneous (SubQ) injections place testosterone into the fat layer just below the skin rather than deep in muscle. A review in The Journal of Clinical Endocrinology and Metabolism described subcutaneous testosterone as a safe, practical, and reasonable option, and many clinics now prescribe it as a standard method.
The two recommended subcutaneous sites are the abdomen and the thigh. For the abdomen, inject about 3 to 5 centimeters (roughly 1.5 to 2 inches) to the side of the navel, into the pinchable fat on either side. Avoid the area directly around the belly button and stay below the ribcage. For the thigh, pinch a fold of fat on the front or outer surface and inject at a shallow angle.
Subcutaneous injections use a much smaller needle, typically a 25-gauge, 5/8-inch needle with a 1-mL syringe. The smaller needle makes the injection nearly painless for most people and is a major reason some prefer this method, especially on a frequent injection schedule.
How IM and SubQ Injections Compare
The practical differences between these two methods come down to needle size, comfort, and injection frequency. IM injections typically use a 23-gauge, 1-inch needle (or 25-gauge, 5/8-inch for smaller patients), while SubQ injections use a thinner 25-gauge, 5/8-inch needle. The thinner needle and shallower depth make subcutaneous shots less intimidating for people new to self-injection.
Because subcutaneous tissue releases testosterone more slowly than muscle, some providers prescribe smaller, more frequent subcutaneous doses (such as twice weekly) rather than larger weekly or biweekly intramuscular doses. This can smooth out the peaks and valleys in testosterone levels that some people notice with less frequent IM injections. Both methods effectively raise testosterone into the target range when dosed correctly.
Why Rotating Sites Matters
Injecting in the same exact spot repeatedly can cause scar tissue buildup in muscle or lumps of hardened fat (lipohypertrophy) under the skin. Either problem can slow absorption and make future injections more painful. Rotating between sites gives tissue time to heal between injections.
A simple rotation for IM injections is alternating between the left and right thigh each week. If you also use the ventrogluteal site, you have four locations to cycle through. For subcutaneous injections, you can alternate between the left and right sides of the abdomen and both thighs, giving you four or more spots. Within each general area, shift the exact needle placement by an inch or so each time rather than hitting the identical point.
Injection Technique Tips
Clean the skin with an alcohol swab and let it dry before inserting the needle. For IM injections, insert the needle at a 90-degree angle straight into the muscle. For SubQ injections, pinch a fold of skin and insert at roughly a 45-degree angle, or 90 degrees if the fat layer is thick enough.
You may have learned to pull back on the plunger (aspirate) before injecting to check for blood. The World Health Organization and the Centers for Disease Control and Prevention no longer recommend aspiration for intramuscular injections at standard sites, since the recommended locations are far from large blood vessels and aspiration can increase pain and bruising.
For intramuscular injections, many providers teach the Z-track method: before inserting the needle, use your free hand to pull the skin about 1 to 1.5 inches to one side. Hold it there while you inject, then release after withdrawing the needle. The displaced skin layers slide back and seal the needle track, preventing the oil-based testosterone from leaking back through the tissue. This reduces soreness and the small welts that sometimes form at injection sites.
What To Expect After Injecting
Mild soreness at the injection site is normal, especially with intramuscular shots, and usually fades within a day or two. A small amount of bleeding or bruising is also common and not a concern. Applying gentle pressure with a clean gauze pad for a few seconds after withdrawing the needle helps minimize both.
If you notice a firm lump that doesn’t go away after a week, increasing redness that spreads outward from the site, warmth and swelling that worsens over several days, or signs of infection like fever, those warrant a call to your provider. These complications are uncommon when injection sites are properly cleaned and rotated, but they’re worth recognizing early.