What are the recommended injection sites for testosterone injections?

Recommended Injection Sites for Testosterone

Testosterone injections should be administered intramuscularly into the gluteal muscle as the primary site, with the anterolateral thigh as an acceptable alternative for self-administration, using either traditional IM or the increasingly preferred subcutaneous route. 1, 2

Primary Injection Sites

Gluteal (Buttocks) Region

• The gluteal muscle is the FDA-approved and most traditional site for testosterone cypionate and enanthate injections, requiring deep intramuscular administration. 2
• The American College of Gastroenterology recommends gluteal injections when administered by another person (healthcare provider or trained family member). 1
• For gluteal IM injections, use 21-23 gauge needles that are 1.5 inches long to ensure proper muscle penetration. 1
• The gluteal site historically shows fewer overall complaints compared to other sites, though it may be more prone to pain than deltoid or thigh injections. 3

Anterolateral Thigh

• The upper third of the anterolateral thigh is the recommended site for self-administration of testosterone injections. 1
• For thigh injections in leaner patients, 1-inch needles may suffice, while larger individuals may require longer needles. 1
• This site allows patients to visualize the injection area and perform self-administration more easily than gluteal injections. 1

Intramuscular vs Subcutaneous Administration

Subcutaneous Route (Emerging Preference)

• Subcutaneous administration is increasingly preferred over traditional IM injections due to easier self-administration, less discomfort, and comparable efficacy. 1, 4, 5
• SC injections achieve therapeutic testosterone levels equivalent to IM administration using doses of 50-150 mg weekly, effective across a wide BMI range (19.0 to 49.9 kg/m²). 1, 4
• In a study of 22 patients who switched from IM to SC, all patients preferred SC injections (20 marked preference, 2 mild preference), with none preferring IM. 4
• Minor and transient local reactions occur in approximately 14% (9 out of 63) of patients using SC administration. 4

Traditional Intramuscular Route

• The FDA label specifically states testosterone cypionate is "for intramuscular use only" and "should not be given intravenously," requiring deep gluteal muscle injection. 2
• IM injections cause relatively frequent minor side-effects: approximately 29.4% of injections result in complaints, mostly pain and bleeding. 3
• Rare but notable: sudden-onset non-productive cough with faintness occurs in approximately 1.5% of injections, possibly due to pulmonary oil microembolism. 3

Special Considerations for Testosterone Undecanoate

• Testosterone undecanoate must be administered as gluteal intramuscular injection only—no other sites are acceptable for this formulation. 1
• This long-acting formulation requires 750 mg initially, 750 mg at 4 weeks, then 750 mg every 10 weeks. 1

Sites to Avoid

Deltoid (Upper Arm)

• While the deltoid was studied in older research for testosterone injections, it is not mentioned in current guidelines as a recommended site. 3
• The middle third posterior aspect of the upper arm is reserved for insulin and other subcutaneous medications, not testosterone. 6

Abdomen

• The abdomen is not a recommended site for testosterone injections, despite being appropriate for insulin and GLP-1 agonists. 6

Common Pitfalls and How to Avoid Them

Inadequate Needle Length

• Failed IM injections often result from subcutaneous deposition rather than true intramuscular delivery. 7
• In obese individuals and those with endomorph body types, standard needle lengths frequently result in subcutaneous rather than intramuscular injection. 8
• Females have significantly thicker subcutaneous fat at gluteal sites (success rate only 36% at baseline vs 66% in males), requiring longer needles or preferential use of the ventrogluteal approach. 7, 8

Improper Injection Technique

• Quick needle insertion (rather than slow advancement) is associated with successful delivery. 7
• Using the non-syringe hand to compress the injection site improves success rates. 7
• Proper landmark identification is critical—nurses who used anatomical landmarks had significantly better success rates. 7

Site Selection in Special Populations

• Both gluteal injection sites should be avoided in obese individuals (BMI >30) and endomorph body types due to excessive subcutaneous fat thickness. 8
• For obese patients, consider switching to subcutaneous administration or transdermal formulations rather than attempting IM gluteal injections. 1, 8

Practical Needle and Supply Recommendations

• Drawing needle: 18-gauge for withdrawing testosterone from the vial. 1
• Injection needle for IM: 21-23 gauge, 1-1.5 inches (1.5 inches for gluteal, 1 inch may suffice for thigh in lean patients). 1
• Syringe size: 1-3 mL syringes, with 3 mL most common for typical 100-200 mg doses. 1
• Always prescribe alcohol prep pads, gauze, adhesive bandages, and a sharps container. 1