What gauge needle is recommended for intramuscular (IM) testosterone injections?

Needle Gauge for Testosterone Injections

For intramuscular testosterone injections in adults, use a 22-25 gauge needle that is 1-1½ inches in length, administered into the deltoid muscle or anterolateral thigh. 1, 2

Intramuscular (IM) Administration - Traditional Route

The CDC recommends 22-25 gauge needles for all adult intramuscular injections, with needle length of 1-1½ inches to ensure adequate muscle penetration. 1, 2 This gauge range provides sufficient bore diameter for the viscous oil-based testosterone preparations while minimizing tissue trauma.

Key Technical Points:

• Inject at a 90-degree angle into the muscle mass to prevent subcutaneous seepage, which can cause local irritation and granuloma formation with oil-based preparations. 1
• Preferred injection site is the deltoid muscle in adults, with the anterolateral thigh as an acceptable alternative. 1, 2
• Avoid the buttock due to risk of sciatic nerve injury and decreased drug absorption from inadvertent injection into deep fat tissue. 1, 2
• The needle must be long enough to reach muscle but not so long as to involve underlying nerves, blood vessels, or bone. 1

Subcutaneous (SC) Administration - Emerging Alternative

Recent evidence demonstrates that subcutaneous testosterone is equally effective and may be preferred by patients. 3, 4 For SC administration, a 27-gauge needle that is 5/8-inch in length has been successfully used in clinical studies. 5

Advantages of SC Route:

• Easier self-administration with less discomfort compared to IM injections. 3, 4
• Stable serum testosterone levels between weekly injections without supraphysiologic peaks. 6
• All 63 patients in one study achieved therapeutic testosterone levels with SC administration (50-150 mg weekly doses), and 20 out of 22 patients who switched from IM to SC had a marked preference for the SC route. 3
• Effective across wide BMI range (19.0-49.9 kg/m²). 3

SC Technical Considerations:

• Administer at a 45-degree angle into subcutaneous tissue of the abdomen, thighs, or upper arm. 1, 2
• Minor, transient local reactions occurred in only 9 out of 63 patients. 3
• Weekly dosing (rather than every 2 weeks) maintains more stable levels with SC route. 6

Common Pitfalls to Avoid

• Do not use needles that are too short for IM injections, as this risks subcutaneous deposition of the oil-based testosterone, causing local irritation, induration, and granuloma formation. 1
• Avoid injection into areas with lipohypertrophy, scars, or tissue abnormalities if using SC route. 2
• Do not routinely use the gluteal region due to sciatic nerve injury risk and decreased bioavailability. 1, 2

Practical Algorithm

For patients new to testosterone therapy:

• Start with SC administration using 27-gauge, 5/8-inch needle if patient comfort and self-administration are priorities. 3, 5
• Use IM administration with 22-25 gauge, 1-1½ inch needle if following traditional protocols or if patient has very low body fat where SC may not be suitable. 1, 2

For patients currently on IM who experience discomfort:

• Consider switching to SC route with smaller gauge needle (27-gauge), as this consistently shows high patient preference and equivalent efficacy. 3, 4