Subcutaneous Testosterone for Women: Recommendation
For women requiring low-dose testosterone therapy, subcutaneous injection is strongly preferred over intramuscular injection due to superior safety, ease of self-administration, and more stable pharmacokinetics—though transdermal formulations remain the gold standard when available.
Route Selection: Subcutaneous vs Intramuscular
Subcutaneous Administration is Preferred for Injectable Therapy
Subcutaneous testosterone achieves therapeutic levels equivalent to intramuscular administration across a wide BMI range (19.0–49.9 kg/m²), with doses of 50–150 mg weekly in transgender patients demonstrating stable serum concentrations between injections 1, 2.
Patient preference overwhelmingly favors subcutaneous over intramuscular: among 22 patients who switched from IM to SC, 20 had a marked preference and 2 had a mild preference for SC, with zero preferring IM 2.
Subcutaneous injections are relatively painless and easy to self-administer, eliminating the need for clinic visits or assistance from others, which is a significant practical advantage over IM injections that often require administration by healthcare providers 3, 2.
Serum testosterone levels remain stable between weekly subcutaneous injections, with mean total testosterone of 627 ± 206 ng/dL and free testosterone of 146 ± 51 pg/mL maintained throughout the dosing interval in FTM patients 3.
Critical Safety Considerations for Women
Why Standard Male Doses Are Dangerous for Women
Male-designed injectable testosterone products (100–200 mg every 2 weeks) deliver doses 30–60 times higher than the proven effective female dose of 300 µg/day, making accurate female dosing virtually impossible with standard formulations 4.
Female physiologic testosterone targets (20–70 ng/dL total testosterone) cannot be achieved with male-oriented injectable formulations, which aim for 500–600 ng/dL to treat male hypogonadism 4.
Injectable testosterone carries a 43.8% risk of erythrocytosis in men compared with 15.4% for transdermal therapy; because women have lower baseline hemoglobin, the relative risk of polycythemia-related complications would be amplified if the same formulation were used 4.
The cardiovascular-event risk linked to injectable testosterone—attributable to time spent in both supratherapeutic and sub-therapeutic serum concentrations—is considered unacceptable for postmenopausal women who already have elevated baseline cardiovascular risk 4.
Practical Dosing Algorithm for Women
Starting Dose and Titration
Begin with extremely low doses: For women, start with 5–10 mg subcutaneously weekly (not the 50–100 mg used in male hypogonadism), as this approximates the 300 µg/day transdermal dose when accounting for pharmacokinetic differences 4.
Weekly dosing is strongly preferred over biweekly because it reduces the problematic peaks and troughs inherent to testosterone esters, which may contribute to cardiovascular risk 1.
Monitor testosterone levels midway between injections 2–3 months after initiation, targeting female physiologic range of 20–70 ng/dL total testosterone (not the 500–600 ng/dL male target) 1, 4.
Adjust dose based on both serum levels and clinical response (improvement in sexual desire, energy, mood), with typical adjustments in 2.5–5 mg increments 1.
Monitoring Protocol
Essential Safety Surveillance
Measure total and free testosterone at 2–3 months after initiation or dose change, then every 6–12 months once stable 1.
Monitor hematocrit/hemoglobin at each visit due to erythrocytosis risk, though this risk is lower with weekly dosing and appropriate female-range targets 5, 4.
Assess for androgenic side effects including acne, hirsutism, voice deepening, and clitoral enlargement at each visit 6, 7.
Monitor lipid profiles every 3 months initially, as supraphysiologic testosterone can reduce HDL cholesterol 5, 6.
Liver function tests are not routinely required for injectable testosterone, as non-alkylated esters do not cause hepatotoxicity 5.
Transdermal Remains the Gold Standard
Why Transdermal is Preferred When Available
Transdermal testosterone provides controlled, steady release avoiding hepatic first-pass metabolism and reproducing physiologic diurnal rhythm, eliminating the mood, energy, and sexual-function fluctuations seen with injectable formulations 4.
Transdermal formulations have markedly lower erythrocytosis risk (15.4% vs 43.8% for IM injections in men), making them inherently safer for women 5, 4.
Local testosterone application (1% gel 5 g twice weekly) has been successfully used in women with hypoactive sexual desire disorder, with dramatic improvement in libido and sexual function within 3 weeks 6.
The main disadvantage of transdermal preparations is cost ($2,135 annually vs $156 for IM) and potential for transfer to partners or children through skin contact 5.
Common Pitfalls to Avoid
Never use standard male dosing protocols in women—this will result in supraphysiologic levels, virilization, and increased cardiovascular/hematologic risk 4.
Do not target male testosterone ranges (500–600 ng/dL); women require levels in the 20–70 ng/dL range to avoid adverse effects while achieving therapeutic benefit 4.
Avoid biweekly dosing schedules as they create dramatic peaks (days 2–5) and troughs (days 10–14) that amplify cardiovascular risk and symptom fluctuation 1, 4.
Do not assume subcutaneous and intramuscular are interchangeable without dose adjustment—absorption kinetics differ, requiring individualized titration based on serum levels 1.
Monitor for mild androgenic effects (facial acne, mild hirsutism) which may resolve after dose reduction or discontinuation, as demonstrated in the case report where acne resolved 2 months after completing treatment 6.