Testosterone Therapy for Men with Low Testosterone and Decreased Libido
For men with decreased libido, measure morning total testosterone levels and offer testosterone therapy if levels are below 300 ng/dl (10.4 nmol/liter), as this is the only prescription medication with guideline-supported evidence for improving libido in this population. 1
Diagnostic Approach
Before initiating any treatment, confirm the diagnosis:
- Measure morning total testosterone on two separate occasions to confirm low levels (below 300 ng/dl) 1, 2
- Consider measuring free or bioavailable testosterone if total testosterone is borderline 2
- Evaluate for other causes of decreased libido: hyperprolactinemia, depression, medications (especially antidepressants, antihypertensives), and systemic illness 3
The guidelines are clear that testosterone therapy should only be offered to men with documented low testosterone levels, not as a general treatment for decreased libido in men with normal testosterone 1.
Treatment Recommendations for Men
When Testosterone is Appropriate
Testosterone therapy improves libido in hypogonadal men (those with testosterone <300 ng/dl), with randomized trials showing large improvements despite some inconsistency in results 1, 2. The Endocrine Society provides a moderate-strength recommendation (Grade 2) for this indication 1.
Testosterone Formulations and Dosing
Choose from these evidence-based regimens 1, 4:
- Injectable testosterone enanthate or cypionate: 75-100 mg IM weekly, or 150-200 mg every 2 weeks
- Testosterone gel (1%): 5-10 g applied daily to covered nongenital skin (wash hands after application; cover site with clothing to prevent transfer)
- Testosterone patches: One or two 5-mg patches applied nightly to back, thigh, or upper arm
- Buccal testosterone: 30 mg tablet applied to buccal mucosa every 12 hours
Target testosterone levels during treatment should be in the mid-normal range (400-700 ng/dl) 1.
Mandatory Monitoring and Contraindications
Do not initiate testosterone if the patient has 2, 1:
- Prostate cancer or breast cancer
- PSA >3 ng/ml without urological evaluation
- Palpable prostate nodule or induration
- Hematocrit >50%
- Severe untreated benign prostatic hypertrophy (IPSS >19)
- Untreated obstructive sleep apnea
- Uncontrolled severe heart failure
Required monitoring schedule 1:
- At 3-6 months: Check testosterone levels, hematocrit, PSA (in men ≥40 years with baseline PSA >0.6 ng/ml), assess symptom response
- Annually thereafter: Continue same monitoring
- Obtain urological consultation if: PSA increases >1.4 ng/ml in any 12-month period, PSA velocity >0.4 ng/ml/year, or new prostate abnormality on exam
Treatment Recommendations for Women
For premenopausal women with hypoactive sexual desire disorder, flibanserin is the only FDA-approved medication 5, 6. However, the evidence shows minimal benefit: women experience approximately one additional satisfying sexual event every 2 months 7, with significant side effects including dizziness, somnolence, nausea, and fatigue 7. Flibanserin is completely contraindicated with alcohol 8.
Bremelanotide is another FDA-approved option for premenopausal women with acquired, generalized hypoactive sexual desire disorder 6.
For postmenopausal women with dyspareunia affecting sexual desire:
- Vaginal DHEA (prasterone) can improve sexual desire, arousal, and pain 5
- Ospemifene (a SERM) is approved for dyspareunia in women without breast cancer history 5
Important caveat: The FDA label for prasterone warns that exogenous estrogens are contraindicated in women with a history of breast cancer 5.
Critical Clinical Pitfalls
Do not prescribe testosterone to men with normal testosterone levels and decreased libido - the evidence shows no benefit 1, 2
Do not use testosterone as monotherapy for erectile dysfunction - evaluate and treat underlying causes first; consider PDE5 inhibitors as first-line for ED 1, 9
Testosterone gel transfer risk is real - counsel patients to cover application sites and wash skin before skin-to-skin contact with partners or children 1
Older men require individualized assessment - do not offer testosterone routinely to all older men with low testosterone; weigh risks versus benefits carefully, particularly regarding cardiovascular and prostate risks 1
For women, set realistic expectations - flibanserin shows statistically significant but clinically modest improvements, with women reporting "minimal improvement to no change" on global impression scores 7
The evidence strongly supports that decreased libido requires a hormonal diagnosis before hormonal treatment - measuring testosterone in men is essential, and treatment should only proceed if levels are unequivocally low 1, 2, 1.