How to Inject Testosterone: Subcutaneous vs. Intramuscular

If your TRT protocol uses testosterone cypionate or enanthate (the two most common esters), you'll be injecting it. The good news: it's easier than you think. Millions of men do it at home safely. The technique takes about 10 minutes to learn and less than 2 minutes to perform once you're comfortable.

This guide walks through both subcutaneous and intramuscular methods, and why the field has shifted toward subcutaneous.

Subcutaneous vs. intramuscular, which is better?

Historically, testosterone was always injected intramuscularly (IM). That's what the vial labels say. But modern research, and a decade of real-world clinical experience, show subcutaneous (SubQ) injections work equally well, with real advantages:

Research comparing the two consistently shows equivalent total and free testosterone levels with either method, at equal doses. Most modern telehealth TRT protocols (including OPTML's) default to subcutaneous.

Supplies you need

• Testosterone cypionate or enanthate vial
• Drawing needle, 18g or 20g, 1 inch (larger gauge to draw oil quickly)
• Injection needle, for SubQ: 29-31g, 1/2 inch. For IM: 25g, 1 inch.
• 1 mL or 3 mL syringe
• Alcohol prep pads
• Sharps container
• Gauze / bandage (optional)

If OPTML is your provider, these ship to you directly, no pharmacy runs required.

Step-by-step: subcutaneous injection

Step 1, Wash hands

Soap and water, 30 seconds. Non-negotiable.

Step 2, Prepare your supplies

Lay out: syringe, drawing needle, injection needle, alcohol pads, your T vial. Open the vial's plastic cap if new.

Step 3, Attach the drawing needle

Screw the drawing needle onto your syringe. Keep cap on until you're drawing.

Step 4, Wipe the vial top

Alcohol pad, one pass across the rubber stopper.

Step 5, Draw air into the syringe

Pull the plunger back to the amount you plan to draw (e.g., 0.5 mL if your dose is 70 mg and concentration is 200 mg/mL, so 70/200 = 0.35 mL).

Step 6, Inject the air into the vial

Flip the vial upside down. Insert needle, push air in. This equalizes pressure and makes drawing easier.

Step 7, Draw your dose

With the vial still inverted and needle submerged in the oil, pull the plunger to your target volume. Tap out any air bubbles.

Step 8, Swap to the injection needle

Remove the drawing needle. Attach the tiny injection needle (29-31g for SubQ).

Step 9, Pick your injection site

Best SubQ sites:

• Lower abdomen, 2+ inches from navel
• Upper outer thigh
• Love handle / flank area

Rotate sites each injection.

Step 10, Clean the site

Alcohol pad. Let dry 10 seconds.

Step 11, Pinch and inject

Pinch about 1-2 inches of skin/fat. Insert the needle straight in (90°) or at 45°, either works for SubQ. Push the plunger slowly (about 10 seconds for the full dose).

Step 12, Withdraw and dispose

Pull the needle straight out. Apply gentle pressure with gauze if needed. Drop the needle in your sharps container immediately, don't recap.

Step-by-step: intramuscular injection

Similar process, but:

• Use a 25g, 1-inch needle for injection (thicker + longer)
• Best sites: ventrogluteal, quadriceps (vastus lateralis), deltoid
• Insert needle at 90° to the muscle
• Inject slowly (30-60 seconds for full dose to minimize PIP, post-injection pain)
• Some providers recommend an "aspiration check", pulling back slightly to ensure you're not in a blood vessel, though modern consensus is this isn't strictly necessary at standard sites

Injection frequency

Modern protocols favor twice-weekly injections (e.g., Monday and Thursday) over once-weekly. Benefits:

• Smaller per-injection volume (less discomfort)
• Steadier testosterone levels (smaller peaks and valleys)
• Reduced estradiol fluctuations
• Better symptom control

Some men do even better with three-times-weekly micro-injections. Talk to your provider.

What about HCG injections?

If your protocol includes HCG (most modern protocols do), it's also subcutaneous with a tiny insulin needle. Same technique, smaller volume. See our HCG on TRT guide.

Common issues and solutions

Injection site soreness

Common for first few weeks. Rotate sites. If using IM, slow the injection speed. Warm compress after can help.

Small lump at injection site

Usually benign, oil absorbs over hours to days. Rub gently after injection. If it persists or becomes red/hot, check with your provider.

Blood after withdrawing needle

Normal occasionally. Apply gentle pressure for 30 seconds. Bruising occasionally occurs and is fine.

Fear of needles

Very common. For most men it disappears after 3-4 injections. A 31g insulin needle is painless for most people, you'll barely feel it.

Safety and disposal

• Never reuse needles, even if they "look clean"
• Never share needles, ever
• Use a sharps container, available at most pharmacies for a few dollars
• Dispose of full sharps containers properly, most pharmacies take them back

The bottom line

Testosterone injection is simple once you've done it a few times. Subcutaneous with a tiny insulin needle is the modern default, equivalent effectiveness, far less pain, and easier technique. Twice-weekly dosing produces better results than once-weekly. Rotate sites, take your time, and don't rush the process.