Can testosterone therapy cause low libido?

Can Testosterone Therapy Cause Low Libido?

No, testosterone therapy does not cause low libido—it treats low libido in men with confirmed hypogonadism. In fact, testosterone replacement therapy (TRT) is specifically indicated to improve diminished sexual desire and sexual function in hypogonadal men, with moderate-certainty evidence showing small but clinically meaningful improvements 1.

How Testosterone Therapy Affects Libido

Testosterone therapy improves, not worsens, sexual desire in hypogonadal men. The most recent high-quality evidence from the TRAVERSE Sexual Function Study (2024) demonstrated that TRT significantly improved sexual activity and sexual desire over 24 months in middle-aged and older men with documented hypogonadism and low libido 2. The American College of Physicians' comprehensive evidence review found that testosterone treatment was associated with a standardized mean difference of 0.44 for sexual desire improvement, which represents a clinically meaningful benefit 1.

Expected Benefits on Sexual Function

• Sexual desire increases significantly with testosterone therapy in men with confirmed low testosterone, with effect sizes of 0.44-0.45 in the highest quality trials 1
• Sexual activity improves by approximately 0.47-0.49 acts per day compared to placebo at 6-12 months, with sustained effects at 24 months 2
• Overall sexual function shows small but meaningful improvement with a pooled standardized mean difference of 0.35 across multiple trials 1
• Erectile function may improve modestly (SMD 0.27), though this effect is smaller and less consistent than improvements in libido 1

When Testosterone Might Not Help Libido

The critical caveat: testosterone only improves libido in men with documented hypogonadism. Several scenarios explain why some men may not experience libido improvement despite testosterone therapy:

Wrong Diagnosis

• Testosterone prescribed without confirmed low levels: Approximately 20-30% of men receiving testosterone in the United States do not have documented low testosterone before treatment initiation 3
• Normal testosterone levels (eugonadal men): The European Association of Urology explicitly recommends against testosterone therapy in eugonadal men, as it provides no benefit and may cause harm 3
• Insufficient diagnostic confirmation: Diagnosis requires two separate morning testosterone measurements below 300 ng/dL (8-10 AM), not just symptoms alone 3, 4

Multifactorial Sexual Dysfunction

• Erectile dysfunction from vascular causes: Low libido may be secondary to frustration with erectile problems rather than testosterone deficiency 5
• Psychological factors: Depression, anxiety, relationship issues, and stress can impair sexual desire independent of testosterone levels 5, 6
• Other medical conditions: Diabetes, cardiovascular disease, sleep apnea, and medications can all reduce libido regardless of testosterone status 6

Paradoxical Suppression (Rare but Important)

• Exogenous testosterone suppresses endogenous production: In men who were not truly hypogonadal, testosterone therapy can suppress the hypothalamic-pituitary-gonadal axis, potentially leading to testicular atrophy and reduced endogenous testosterone production after discontinuation 4, 7
• Fertility suppression effects: Testosterone causes azoospermia by suppressing FSH and LH, which is absolutely contraindicated in men seeking fertility 3, 4

Clinical Algorithm for Low Libido on Testosterone Therapy

Step 1: Verify True Hypogonadism

• Confirm pre-treatment testosterone levels: Review whether two morning measurements (8-10 AM) showed levels <300 ng/dL before therapy initiation 3
• Check current testosterone levels: Measure testosterone midway between injections (for injectable) or after steady-state (for transdermal), targeting 500-600 ng/dL 3, 4
• If testosterone was never low: Discontinue therapy, as the patient is eugonadal and will not benefit 3

Step 2: Assess for Other Sexual Dysfunction Causes

• Evaluate erectile function separately: Consider adding PDE5 inhibitors if erectile dysfunction is the primary issue, as testosterone has minimal effect on erectile function (SMD 0.27) 1
• Screen for depression and relationship issues: Testosterone has minimal effect on mood (SMD -0.19) and will not address psychological causes of low libido 3
• Review medications: Antidepressants (especially SSRIs), antihypertensives, and other drugs commonly impair libido 6
• Assess cardiovascular health: Vascular disease affects both erectile function and overall sexual function 1, 5

Step 3: Optimize Testosterone Delivery

• Consider formulation switch: Transdermal preparations provide more stable day-to-day levels than intramuscular injections, which may improve symptom control 3
• Adjust dosing: Ensure testosterone levels are in the mid-normal range (500-600 ng/dL), not supraphysiologic or subtherapeutic 3, 4
• Monitor for adverse effects: Erythrocytosis (hematocrit >54%) can cause fatigue and indirectly affect sexual function 3, 4

Step 4: Set Realistic Expectations and Timeline

• Reassess at 12 months: If no improvement in sexual function after one year of adequate testosterone replacement, discontinue therapy 3
• Explain limited benefits: Testosterone improves libido and sexual desire but has little effect on energy, vitality, physical function, or cognition 1, 3
• Consider combination therapy: For men with both low testosterone and erectile dysfunction, combining testosterone with PDE5 inhibitors may be more effective than either alone 1

Common Pitfalls to Avoid

Never diagnose hypogonadism based on symptoms alone—the European Association of Urology explicitly warns that screening questionnaires lack specificity, and biochemical confirmation with two morning testosterone measurements is mandatory 3.

Never assume testosterone will fix all sexual problems—the relationship between testosterone and sexual function is complex and influenced by vascular, psychological, and relational factors that testosterone cannot address 5, 6.

Never continue testosterone indefinitely without reassessment—if sexual function has not improved after 12 months of adequate replacement, the patient likely has other causes of sexual dysfunction that require different interventions 3.

Never prescribe testosterone to men actively seeking fertility—exogenous testosterone causes azoospermia and is absolutely contraindicated in this population; gonadotropin therapy (hCG plus FSH) should be used instead 3, 4.