How to Inject Testosterone Correctly: The Doctor Technique Step-by-Step Guide

Inject testosterone correctly is critical for men on TRT. For many patients, self-administered testosterone therapy has become an essential part of their health routine, with the convenience of at-home injections being a significant benefit. Others prefer to go into a clinic once a week to have a clinician administer the injection for them. This step-by-step guide will help to outline how patients can safely inject their medications at home!

Proper technique matters! Intramuscular injections deliver medication to the bloodstream quickly, but they typically require specific equipment and careful administration. From selecting the right injection sites to knowing what size needle for testosterone injection to use (usually 22-23 gage and 1-1.5 inches in length), each step must be performed correctly. MOST importantly, safety precautions like thorough handwashing are CRTITICAL to prevent infections (wash those hands! Yes, even if you are gloving).

In this physician-approved guide, we'll walk you through everything you need to know about how to properly inject testosterone. Whether it’s your first time on TRT or you’re looking to refine your technique, here’s what you need to know to help you administer your treatment safely and effectively.

Gathering Supplies and Preparing the Area

Before starting any testosterone injection routine, prepare properly. Setting up correctly in the beginning will set you up for success and also minimizes risks of contamination and infection.

Checklist of materials needed

For successful testosterone self-injection, make sure to gather:

• Testosterone medication (vial) – ensure that the medication hasn't expired and appears clear without foreign particles or discoloration.
• Drawing needle (typically 18-gage, 1½ inch) for extracting medication
• Injection needle (sizes vary by injection method)
  • For intramuscular: 22-23 gage, 1-1½ inch length
  • For subcutaneous: 25-27 gage, ½-⅝ inch length
• Insulin syringe or other syringe with markings
• Alcohol swabs (at least two - one for vial, one for skin)
• Clean paper towels
• Sharps disposal container

Arrange all the supplies on a clean surface before washing your hands, creating an organized workspace that prevents contamination.

Why handwashing and surface cleaning matter

Thorough handwashing represents the single most important step in preventing infection during self-injection. Use soap and water (or disinfectant alcohol) before handling any injection supplies.

For clinical grade preparation, also disinfect the surface where you’ll be placing your supplies. Since testosterone injections bypass the body's natural barriers by piercing the skin, even minor contamination can lead to infection.

How to handle testosterone safely

Testosterone should be stored at room temperature (20-25°C/68-77°F) in a dry place away from moisture, heat, and direct light. The medication vial needs protection from light exposure to maintain potency. This should be a given, although maybe someone reading this needs to hear it, for safety reasons keep all testosterone medication away from children and pets.

When handling multiple-dose vials, clean the rubber stopper with an alcohol swab before inserting any needle. And once finished with the treatment, care must be taken to properly dispose of your sharps and used supplies (all used needles and syringes immediately go into a puncture-proof sharps container). Under no circumstances should you flush medications down the toilet or throw needles in regular trash.

Following these preparation steps creates a foundation for safe and effective testosterone administration, while preventing both personal injury and environmental contamination.

Choosing the Right Injection Site

Selecting the correct injection site is critical for maximizing testosterone absorption while minimizing discomfort. Your choice of location affects both safety and ease of self-administration.

Thigh vs glute: pros and cons

The vastus lateralis (thigh) and gluteus maximus (buttocks) are the two primary testosterone injection sites, each with distinct advantages.

The thigh offers excellent accessibility for self-injection and contains adequate muscle mass for proper absorption. Generally, this site causes less bleeding but may be more painful than other options.

Alternatively, the gluteal site (buttocks) typically provides the most comfortable injection experience with minimal post-injection discomfort from our experience. This area has fewer complaints and less bleeding compared to other sites. The upper outer quadrant contains fewer nerve endings and blood vessels, making it safer for injection.

Some patients prefer to use the shoulder/deltoid muscle due to familiarity with the muscle. This site is safe to use as well although due to being a smaller muscle (compared to the thigh and buttocks) can cause increased pain with higher volumes of medication.

NOTE: Regardless of the site chosen, the medication is absorbed systemically (from the muscles in the blood stream). So, there is no advantage or added benefit to the particular muscle that is being injected as sometimes people wrongly assume that by injecting into a shoulder let say, they will get bigger shoulders.  

How to locate the vastus lateralis muscle

To find the vastus lateralis, I divide my thigh horizontally into three equal sections. The injection goes into the outer middle third of the thigh. Specifically:

1. Sit down and create imaginary lines: one above the knee, another at the uppermost part of the thigh
2. Draw an imaginary line down the outer side and center front of the leg
3. The injection site is within these boundaries, on the outer portion

When to use the gluteus maximus

The gluteus maximus is ideal when someone else can administer the injection. To locate the proper site, divide each buttock into four parts mentally. The injection should go into the upper outer quarter, away from the spine and toward the hip bone. This placement avoids the sciatic nerve that runs through the central portion of the buttock.

Check out our doctor guided TRT protocols for personalized advice on injection techniques that might work best for your specific situation.

Rotating testosterone injection sites

Rotating injection sites is essential to prevent tissue damage and scarring. Each new injection should be about one inch away from previous sites. Essentially, I should use all available sites in one body area before moving to another. This practice prevents hardening of fatty tissue that could interfere with medication absorption.

How to Properly Inject Testosterone

Proper injection technique is the cornerstone of effective testosterone replacement therapy. Once I've selected my injection site and gathered supplies, the next critical steps involve medication preparation and administration.

Drawing the correct dose from the vial

Initially, you need to prepare the testosterone for injection:

1. Clean the vial's rubber stopper with an alcohol swab and let it dry
2. Pull the plunger back to draw air equal to your prescribed dose
3. Insert the drawing needle (18-20 gage) into the vial and push the air in
4. Slowly pull back the plunger to my exact dose
5. Tap the syringe gently to remove air bubbles

What size needle for testosterone injection

The correct needle size ensures proper delivery with minimal discomfort. For testosterone injections, 23-gage, 1-inch and 25-gage, 1-inch needles are standard. Smaller gage needles (higher numbers) reduce tissue scarring after years of therapy but may take longer to withdraw the solution.

Switching from drawing needle to your injection needle

After drawing medication, you must replace the needle:

1. Recap the drawing needle
2. Remove it from the syringe without touching the syringe tip
3. Attach a new, sterile injection needle
4. This prevents injection with a dulled needle, reducing pain and tissue damage

How to give testosterone shot at a 90-degree angle

1. Hold the syringe like a dart with my dominant hand
2. Stretch the skin taut with my other hand
3. Insert the needle completely at a 90-degree angle in one quick, firm motion
4. Release the stretched skin after insertion
5. Slowly depress the plunger to inject the medication
6. Wait 3-5 seconds and withdraw the needle straight out

Tips to reduce pain and discomfort during injection

• Allow testosterone vial to reach room temperature before injecting
• Apply ice to numb the skin area 15 minutes before injection=
• Let your skin dry after alcohol cleaning
• Try to relax the target muscle completely during injection (injecting in tense muscles causes fiber pain)
• Inject slowly and steadily—letting your muscle expand easily to take in the medication.

Check out our doctor guided TRT protocols for personalized TRT treatements tailored to your specific needs!

What to do immediately after injection

Once you have withdrawn the needle from your skin, dispose of the needle and syringe and then apply direct pressure to the injection site with a clean cotton ball or gauze. The pressure will help to reduce any bleeding at the site. Afterwards apply a bandage if needed.

To minimize bruising, avoid rubbing the injection site. Instead, apply gentle “press and hold” technique like you are pressing down on a button. Minor redness and tenderness are common at injection sites, these typically resolve within a few days.

How to dispose of needles and syringes

Never throw used needles into a regular trash can or flush them down any toilets. Always immediately place the entire needle and syringe (without recapping) into a proper sharps disposal container.

For my sharps container, I use either:

• An FDA-cleared container purchased from a pharmacy or medical supply store
• A heavy-duty plastic household container (like a laundry detergent bottle) as an alternative

Never fill containers more than three-quarters full as you don’t want to have any needles sticking out. Once ¾ full, seal the container and dispose of it as per your local regulations, which may include drop-off at collection sites, mail-back programs, or special waste pickup service.

Signs of infection or complications to watch for

• Fever above 100.4°F (38°C)
• Increasing redness, pain, warmth, or swelling at the injection site
• Red streaks spreading from the area
• Pus or discharge from the site
• Muscle aches or unusual fatigue

For severe reactions such as trouble breathing, facial swelling, or hives, seek emergency care immediately as these may indicate a life-threatening allergic reaction.

TL;DR Final Thoughts

Testosterone injection for TRT requires an attention to detail throughout the entire process. Following proper techniques ensures both safety and effectiveness of this important treatment. Undoubtedly, the benefits of self-administered testosterone therapy make learning these procedures worthwhile.

Preparation is KEY for safety. Clean supplies, proper handwashing, and organization significantly reduce infection risks. Selecting the right injection site—whether thigh or gluteal muscle (some do shoulders/deltoid)—affects both comfort and absorption. Most importantly, consistent rotation of sites prevents tissue damage while ensuring optimal medication delivery.

Proper needle selection plays a crucial role in successful administration. The correct gage and length minimize discomfort while maximizing therapeutic benefit. Before each injection, carefully prepare the medication dose, followed by meticulous cleaning and injecting technique at the appropriate angle. Always monitor for potential complications and intervene early if problems arise.

Remember, effective testosterone therapy depends on consistency and precision. Though the process may seem daunting at first, these steps will become routine with practice. Your commitment to mastering proper injection technique ultimately will support your overall health and wellbeing. If you have any questions during self-administration, pause and make sure to consult with your healthcare provider about your TRT.

 

FAQs

What supplies do I need for testosterone injection? 

You'll need testosterone medication, drawing and injection needles, a syringe, alcohol swabs, clean paper towels, and a sharps disposal container. Always check that your medication hasn't expired and appears clear before use.

How do I choose the right injection site?

The two primary sites are the vastus lateralis (thigh) and gluteus maximus (buttocks). The thigh is easier for self-injection, while the buttocks may be more comfortable but often require assistance. Rotate sites to prevent tissue damage. Regardless of the site chosen, the medication is absorbed systemically (from the muscles in the blood stream). So, there is no advantage or added benefit to the particular muscle that is being injected as sometimes people wrongly assume that by injecting into a shoulder let say, they will get bigger shoulders.  

What's the correct needle size for testosterone injections?

For intramuscular injections, 23-gage, 1-inch needles are commonly used. For subcutaneous injections, 25-27 gage, ½-⅝ inch needles are recommended. Always consult your healthcare provider for the most appropriate size for your specific needs.

How can I reduce pain during testosterone injection?

Allow the testosterone to reach room temperature before injecting, ensure the injection site is completely dry after cleaning, apply ice to numb the area beforehand, relax the target muscle, and inject slowly and steadily.

What signs of infection should I watch for after injection?

Monitor for fever above 100.4°F (38°C), increasing pain, warmth, or swelling at the injection site, red streaks spreading from the area, pus or discharge, and unusual generalized muscle aches or fatigue. Seek medical care if you notice these symptoms.