There is no single best testosterone formulation. There is a best formulation for a particular man, and choosing it well is one of the highest-value decisions in this entire course. The variables that should drive the choice are fertility intent, baseline hematocrit, household exposure risk, adherence pattern, injection tolerance, insurance coverage, and how much peak-to-trough variability the patient will tolerate.
Formulation Comparison
| Formulation | Typical adult dosing | Level timing | Key advantages | Key drawbacks |
|---|---|---|---|---|
| Testosterone cypionate (Depo-Testosterone) — IM or SC | 50–100 mg weekly, or 100–200 mg every 2 weeks | Midway between doses for every-2-week dosing; trough (just before next dose) for weekly | Inexpensive, widely covered, reliable absorption, no transference risk | Highest erythrocytosis risk of the common options; peak-and-trough symptom fluctuation on every-2-week dosing |
| Testosterone enanthate (Xyosted, auto-injector SC) | 50–100 mg SC weekly | Trough, before the next weekly dose | Weekly SC dosing smooths peaks; patient-administered auto-injector | Boxed warning for blood pressure increase; cost |
| Testosterone gel 1% or 1.62% (AndroGel, Testim, Vogelxo) | 1.62%: 20.25–81 mg daily applied to shoulders/upper arms | Any time 2–8 hours after application, after ~2 weeks of steady use | Steady daily levels, easy dose titration, lower erythrocytosis risk than injectables | Secondary exposure risk to women and children (boxed warning); daily adherence; variable absorption |
| Testosterone solution 2% (Axiron, axillary) | 30–120 mg daily to the axilla | 2–8 hours after application at steady state | Axillary application reduces some transference scenarios | Transference risk persists; skin irritation |
| Testosterone transdermal patch (Androderm) | 2–6 mg daily, applied nightly | Morning, after overnight wear | Steady levels; no gel transference | High rate of application-site skin reactions |
| Testosterone undecanoate injection (Aveed) | 750 mg IM at baseline, 4 weeks, then every 10 weeks | Just before the next injection | Very infrequent dosing | REMS program required; risk of pulmonary oil microembolism and anaphylaxis; 30-minute post-injection observation |
| Testosterone undecanoate oral (Jatenzo, Tlando, Kyzatrex) | Product-specific; taken twice daily with food | Product-specific, generally a few hours post-dose | Oral route without the hepatotoxicity of methyltestosterone; no transference | Boxed warning for blood pressure increase; must be taken with food; cost |
| Testosterone pellets (Testopel), subcutaneous implant | Typically 6–12 pellets every 3–6 months | End of the dosing interval | Excellent adherence; very stable levels | Minor office procedure; extrusion and infection risk; dose cannot be withdrawn once implanted |
| Testosterone nasal gel (Natesto) | 11 mg per nostril three times daily | Product-specific | Short-acting kinetics may partially spare LH/FSH suppression | Three-times-daily dosing; nasal irritation; limited long-term data |
Subcutaneous administration of testosterone cypionate using a small-gauge needle is widely used in practice, is generally better tolerated than intramuscular injection, and produces comparable or slightly smoother pharmacokinetics. For most products this route is off-label; document the discussion. Weekly SC dosing at half the every-2-week dose is a common and reasonable starting approach.
If a patient describes feeling excellent for five days and then crashing, the problem is usually the dosing interval, not the dose. Splitting an every-2-week injection into weekly halves fixes more symptom complaints than raising the total dose does.
Choosing the Formulation
- 1Fertility desired? → Do not use testosterone monotherapy; refer
- 2Young children or a pregnant partner in the household? → Avoid gels, or use patch/injection
- 3Baseline hematocrit 50–54%? → Prefer transdermal over injectable; monitor early
- 4Poor adherence or needle aversion? → Consider pellets or gel
- 5Cost is the dominant constraint? → Cypionate is by far the least expensive
- 6Wants the fewest possible touches? → Pellets or undecanoate injection
Targets and Titration
The therapeutic target is a total testosterone in the mid-normal range for healthy young men, commonly cited as roughly 400 to 700 ng/dL, measured at the correct time point for the formulation. Higher is not better: supraphysiologic levels increase erythrocytosis, acne, and estradiol-mediated effects without improving symptom outcomes. Reassess symptoms alongside the level; a man at 520 ng/dL who still has low libido has a symptom problem to investigate, not a dose problem to escalate.
- Check the level and symptoms at 3 to 6 months after initiation, then annually once stable.
- Adjust in modest increments; for cypionate, changes of 20 to 25 mg per week are usually sufficient.
- If the level is at target but symptoms persist, revisit the differential from Part II before increasing the dose.
- If the level is supraphysiologic, reduce the dose regardless of how the patient feels.
- If peaks and troughs are the problem, shorten the interval before raising the dose.
The right dose, the wrong schedule
A 49-year-old man has been on testosterone cypionate 200 mg IM every two weeks for four months. He reports feeling 'great for about a week, then flat, irritable, and exhausted for the second week.' A trough level drawn just before his next injection is 265 ng/dL. Hematocrit is 51 percent. He asks whether he needs a higher dose.
What would you change?