TRT Delivery Methods: Patches vs Gels vs Injections

How transdermal TRT works

Transdermal delivery bypasses first-pass hepatic metabolism by moving testosterone across the stratum corneum into the dermal capillary bed. Because the skin is a deliberate barrier, only a small fraction of the applied dose — roughly ten percent for both patches and gels — reaches circulation. The rest is lost to the surface, clothing, or washing.

That inefficiency is the reason transdermal doses look large on paper. It also explains why absorption is sensitive to variables injections never face: application site, skin thickness, hydration, sweating, showering too soon, and body composition. The benefit in exchange is a daily delivery rhythm that keeps serum testosterone in a narrow band rather than sending it up and back down over a week or two.

Transdermal routes also increase conversion to dihydrotestosterone, because skin is rich in 5-alpha reductase. Gels raise DHT more than injections do at comparable serum testosterone. Whether that matters depends on your goals and your risk profile for hair loss and prostate symptoms.

Patches deliver a metered dose over roughly 24 hours and are usually applied at night so peak levels arrive in the early morning, echoing natural secretion. Dosing consistency is their strongest feature: the delivery rate is engineered into the matrix rather than left to how much gel you rubbed in and where.

The costs are practical. Skin irritation at the application site is the most common reason for discontinuation, ranging from mild redness to blistering. Adhesion fails with heavy sweating or swimming. Patches are visible. And they are typically the most expensive of the three routes per month, with fewer generic options than gels or injectable esters.

Patches suit someone who wants a stable daily curve, cannot risk transfer to a partner or child, and tolerates adhesive well.

Gels are applied once daily to clean, dry skin on the shoulders, upper arms, or abdomen depending on the product. They are painless, easy to titrate in small increments, and produce a flat daily plateau similar to patches without the adhesive problem.

Their defining drawback is transfer. Testosterone can move to anyone who contacts the application site before it dries and is covered, and secondary exposure in women and children has documented consequences. The application protocol is therefore not optional: apply after showering, let it dry completely, wash hands, cover the site with a shirt, and avoid skin-to-skin contact at that site.

Gels also drive the highest DHT conversion of the three routes. For most men this is clinically unremarkable; for men with androgenetic alopecia or prostate symptoms it is worth discussing before starting.

Injectable esters — most commonly cypionate and enanthate — are the least expensive and most reliably absorbed route. Delivery does not depend on skin, so inter-individual variability drops sharply and dose changes translate predictably into serum changes.

The tradeoff is the shape of the curve. A single large dose every two weeks produces a supraphysiologic peak in the first days and a symptomatic trough before the next dose, often felt as swings in energy, libido, and mood. Splitting the same weekly total into twice-weekly or daily subcutaneous doses substantially flattens that curve and is now the more common protocol.

Injections also carry the clearest association with erythrocytosis, which is why hematocrit monitoring belongs in every injection protocol. See the injection protocol guide for frequency and technique detail.

What to discuss with your prescribing physician

Bring the decision to your clinician as a set of constraints rather than a product request. The questions that actually change the recommendation are: who lives in your household and could be exposed to a gel; whether you tolerate adhesives; whether you are willing to self-inject and how often; what your baseline hematocrit, PSA, and estradiol look like; whether fertility preservation matters; and what your insurance covers, since cost differences between routes are large.

Ask specifically when trough labs will be drawn, what target range you are aiming for, and what would trigger a route change. A protocol without a monitoring schedule is incomplete regardless of which delivery method you choose.