Subcutaneous Testosterone Injection: Step-by-Step Instructions

How do I give myself a subcutaneous testosterone injection?

Subcutaneous (SC) testosterone goes into the loose fat layer of the abdomen or outer thigh, through a pinched-up skinfold, using a short and fine needle. You use two needles for one injection: a 20G x 1" needle to draw the thick oil out of the vial, then you swap it for a fresh 25G x 1/2" needle to inject. Push slowly, rotate sites every week, and drop the syringe straight into a sharps container. Blood levels come out comparable to intramuscular injection, with less pain and no trip to the office.

In more than two decades of practicing medicine, I have watched the subcutaneous route quietly take over from the old gluteal shot. Not because it is trendy, but because patients actually do it. An injection you dread once a week is an injection you eventually skip. Here is the technique, exactly as we teach it in the office.

Written by Dr. Ty Tallman, NMD, Integrative Medical Partners, Mesa, AZ. Updated September 17, 2026.

What you will need

Item	What it is for
1 cc (1 mL) syringe	Holds the volume. Subcutaneous oil injections are generally 1 mL or less.
20G x 1" needle	Drawing needle. Wide bore pulls the viscous oil out of the vial quickly.
25G x 1/2" needle	Injection needle. Thin and short, so it lands in fat and not muscle.
Alcohol pads	The vial stopper and the skin. Two separate pads.
Gauze or cotton ball	Light pressure afterward.
Sharps container	Disposal. Never household trash.
Your medication vial	Dispensed from our office, labeled with your name and your amount.

Your amount is individualized and set by our office. We mark your syringe line for you at your teaching visit. Never adjust it on your own, and never borrow someone else’s vial or instructions.

Why two different needles

This is the single most useful thing to understand about testosterone injections, and it is the step most people get wrong at home. Testosterone is suspended in oil, and oil is thick. Here is why the pair works:

Drawing through a 25G takes forever and dulls the very needle you are about to put in your skin. A dull tip is what makes an injection hurt.
Injecting through a 20G is unnecessarily wide for a fat-layer injection. It is a bigger hole for no benefit.
The 20G x 1" never touches you. It only ever goes through the rubber stopper. That is its whole job.
Pushing oil through a 25G is slow, and that is fine. Slow delivery into subcutaneous tissue is more comfortable, not less.

Step by step: drawing up

Wash your hands. Lay out the syringe, both needles, two alcohol pads, gauze, and the sharps container.
Inspect the vial. The oil should be clear and free of floating particles. Check the expiration date and that the seal is intact. If it looks cloudy or has visible specks, do not use it — call us.
Flip off the plastic cap on a new vial. Wipe the rubber stopper with alcohol and let it dry.
Attach the 20G x 1" needle to the 1 cc syringe.
Pull the plunger back to your marked line, drawing in that much air.
Push the needle through the center of the stopper and inject the air into the vial. This equalizes pressure so the oil comes out instead of fighting you.
Turn the vial upside down, keep the needle tip in the oil, and pull slowly to your line.
Tap the barrel so bubbles rise, push them back into the vial, and recheck your line. Oil holds bubbles more stubbornly than water, so be patient here.
Withdraw the needle, remove the 20G, and attach a fresh 25G x 1/2". Do not squirt oil out to prime it — that is your medication.

Step by step: giving the injection

Choose your site. The abdomen, roughly two inches out from the navel, is the workhorse. The front or outer thigh is the alternate.
Rotate. Move to a different spot every week and stay away from skin that is bruised, tender, red, hard, or scarred. Repeated hits in one place build up lumpy tissue that absorbs poorly.
Clean the skin with the second alcohol pad and let it dry completely. Wet alcohol stings.
Pinch up a fold of skin. This lifts the fat away from the muscle underneath and is what makes this a subcutaneous injection rather than an accidental intramuscular one.
Insert straight into the fold at 90 degrees. The 1/2" needle is short by design; it goes all the way in.
Push slowly and steadily. Ten to twenty seconds is normal for oil. No aspirating, no pulling back to check for blood — that is an intramuscular habit and it is not needed here.
Withdraw, release the pinch, and press lightly with gauze. Do not rub or massage the site.
Drop the whole syringe into the sharps container. Do not recap, do not reuse, one needle per injection.

Why subcutaneous instead of the old gluteal shot

The evidence here is genuinely good, and it is worth knowing why we moved:

It hurts less. In a 52-week auto-injector study, more than 95% of patients reported no injection-related pain. In a separate 26-week safety study, only 1 of 965 injections caused mild pain.
Levels are comparable. Weekly subcutaneous testosterone cypionate or enanthate achieves serum levels, pharmacokinetics, safety, and tolerability comparable to intramuscular delivery, with steady concentrations between doses.
The curve may be smoother. In a comparative study, subcutaneous enanthate was independently associated with lower post-therapy estradiol and hematocrit than intramuscular cypionate, with no difference in achieved total testosterone or PSA. Smaller peak-to-trough swings may translate into fewer mood, energy, and libido roller coasters.
Patients prefer it. In one study of patients switched from intramuscular to subcutaneous, all 22 preferred the subcutaneous route and none wanted to go back.

The honest caveats. Head-to-head safety trials comparing the two routes are still limited. Subcutaneous use of standard testosterone cypionate or enanthate vials is off-label; only the proprietary auto-injector product carries an FDA-approved subcutaneous indication. And a standard syringe and needle produces more variation in serum levels than that auto-injector does — which matters when we interpret your trough labs. Modestly better is still better, but it is not magic.

When to call us

A hard lump, spreading redness, warmth, or pain that worsens over days rather than improving.
You are not sure you got the full amount in, or you think you hit muscle. Do not repeat the injection. Text us.
Any of the class-wide effects we monitor for: a rising hematocrit, a bump in blood pressure, or new swelling.
Your labs are due. Testosterone therapy is a measured therapy, not a set-and-forget one. Trough timing matters for interpretation, so keep your draw on schedule.

Common questions

Do I need to aspirate before injecting?

No. Pulling back on the plunger to check for blood is an intramuscular technique. There are no large vessels in the pinched fat layer you are targeting.

Is the oil supposed to be this hard to push?

Yes. Testosterone esters are viscous, and a 25 gauge needle is narrow. Slow and steady is correct. If it will not move at all, stop and check that the needle is fully seated on the syringe.

Can I inject into the same spot every week?

No. Rotate. Repeated injections in one area can build up lumpy fatty tissue that absorbs medication unpredictably, which shows up later as confusing labs.

Abdomen or thigh?

Either works. The abdomen usually has more forgiving subcutaneous tissue and is easier to reach one-handed. Lean patients often find the thigh harder to pinch.

What if I think I hit muscle?

It is not an emergency. It generally means absorption for that dose was faster and less predictable. Tell us, so we read your next labs in context, and we will review your pinch technique.

Can I use an insulin syringe instead?

For thick oil preparations, usually not — the needle is too fine to move the oil reasonably. Insulin syringes are the right tool for water-based medications like GLP-1s and many peptides. Ask us before substituting anything.

Related reading: intramuscular testosterone injection, step by step, why testosterone raises your hematocrit and what we do about it, whether donating blood is the right fix, how to read and use an insulin syringe, and how pellets compare if you would rather not inject at all. Your first injection should never be a guess. We teach the technique in the office, mark your syringe, and follow up on how it is going.

Text us at 480-219-2624 to schedule, or call. Quick response, real scheduling, no phone tree. 1910 S Stapley Dr #120, Mesa, AZ 85204.

To Health and Wellness, Dr. Ty Tallman

References

The Journal of Clinical Endocrinology and Metabolism, 2022 — subcutaneous testosterone injection as a safe, practical, and reasonable option
The Journal of Clinical Endocrinology and Metabolism, 2017 — subcutaneous injection as an effective and preferred alternative to intramuscular
The Journal of Urology, 2019 — 52-week study of dose-adjusted subcutaneous testosterone enanthate by auto-injector
The Journal of Sexual Medicine, 2019 — 26-week safety study of a subcutaneous testosterone enanthate auto-injector
The Journal of Urology, 2022 — outcomes with intramuscular cypionate versus subcutaneous enanthate in hypogonadal men
Clinical Endocrinology, 2022 — Society for Endocrinology guidelines for testosterone replacement therapy in male hypogonadism
Advances in Therapy, 2019 — factors influencing pain sensation at the subcutaneous injection site
JAMA, 2026 — adult male hypogonadism review