What are the side effects of testosterone injections?

Side Effects of Testosterone Injections

Testosterone injections can cause numerous side effects including local injection site reactions, erythrocytosis, fluid retention, sleep apnea exacerbation, fertility suppression, and potential cardiovascular effects, requiring careful monitoring and appropriate patient selection. 1, 2, 3

Common Side Effects

Local Injection Site Reactions

• Pain, soreness, bruising, erythema, swelling, nodules, or furuncles at the injection site 1
• Approximately 29.4% of injections cause minor local side effects, primarily pain and bleeding 4
• Gluteal injection sites have fewer overall complaints but more pain compared to deltoid or thigh sites 4

Hematologic Effects

• Erythrocytosis (increased red blood cell count) is dose-dependent, occurring in 2.8-17.9% of patients 2
• Regular monitoring of hemoglobin and hematocrit levels is essential to detect polycythemia 1, 3

Reproductive and Sexual Effects

• Testicular size and consistency often diminish 1
• Fertility is greatly compromised due to gonadotropin suppression 1, 2
• Oligospermia may occur after prolonged administration or excessive dosage 3
• Priapism or excessive sexual stimulation may develop 3

Dermatologic Effects

• Acne, oily skin, increased body hair, and flushing (generally minor inconveniences) 1
• Dermatitis (rare but reported) 5

Serious Side Effects

Cardiovascular Effects

• Fluid retention (uncommon and generally mild) 1
• Caution needed in men with congestive heart failure or renal insufficiency 1
• Hypertension (rarely reported) 1
• Potential for pulmonary oil microembolism (rare - 1.5% of injections) presenting as sudden-onset cough with faintness 4

Prostatic Effects

• May exacerbate benign prostatic hypertrophy, potentially leading to acute urethral obstruction 3
• Potential risk of unmasking previously occult prostate cancer 1
• Regular PSA monitoring and digital rectal examinations are required 1, 2

Sleep Apnea

• Exacerbation or development of sleep apnea, particularly with higher doses and in patients with pre-existing risk factors 1
• Occurs through central mechanisms rather than anatomical airway changes 1

Hepatic Effects

• Intramuscular injections do not appear to cause hepatic dysfunction 1
• Routine liver function monitoring is unnecessary for injectable testosterone 1

Metabolic Effects

• May decrease blood glucose levels in diabetic patients, potentially requiring insulin adjustment 3
• May increase serum cholesterol levels 3

Psychological Effects

• Most doses show minimal effects on mood and behavior 6
• At high doses (500mg/week), a minority of men may experience significant adverse psychological effects including agitation and irritability 6

Monitoring Recommendations

Baseline Assessment

• PSA measurement and digital rectal examination 1, 2
• Hematocrit or hemoglobin level 1, 2
• Assessment of voiding symptoms and sleep apnea history 1
• Optional lipid evaluation 1

Follow-up Monitoring

• First follow-up at 1-2 months to assess efficacy 1
• Subsequent visits at 3-6 month intervals for the first year, then yearly 1
• Monitor testosterone levels 2-3 months after treatment initiation and after dose changes, then every 6-12 months once stable 2
• Regular assessment of symptomatic response, voiding symptoms, and sleep apnea 1
• Blood tests for testosterone levels, PSA, and hematocrit/hemoglobin 1, 2

Contraindications

• Prostate cancer 2
• Breast cancer 2
• Desire for near-term fertility 2
• Severe sleep apnea 2
• Uncontrolled heart failure 2
• Recent cardiovascular events 2

Clinical Pearls

• Target testosterone levels should be in the mid-normal range (approximately 450-600 ng/dL) 2
• Treatment to raise levels above the physiologic range is discouraged 1
• Peak serum testosterone levels may transiently rise above the upper limit of normal with standard injection dosages 1
• Testosterone cypionate should not be used interchangeably with testosterone propionate due to differences in duration of action 3
• Testosterone injections are not for intravenous use 3
• Patients should report any nausea, vomiting, changes in skin color, ankle swelling, or persistent erections 3