Testosterone exists in several forms, both naturally in your body and as pharmaceutical preparations used for hormone therapy. In the bloodstream, testosterone circulates in three states: roughly half is bound to a protein called SHBG, another half is loosely bound to albumin, and only 0.5% to 3% floats freely. When prescribed as a medication, testosterone comes in at least seven distinct delivery formats, each with different schedules, absorption rates, and tradeoffs.
Natural Forms in Your Blood
Your body doesn’t just have “testosterone” as a single measurement. The hormone splits into categories based on what it’s attached to, and this matters because binding determines whether testosterone can actually do its job.
Free testosterone makes up the smallest fraction, just 0.5% to 3% of the total. This is the only form that can directly enter cells and activate androgen receptors. Albumin-bound testosterone accounts for roughly half of your circulating supply. Because albumin holds testosterone loosely, the hormone can detach relatively easily and become active, which is why free and albumin-bound testosterone are grouped together as “bioavailable testosterone.” SHBG-bound testosterone makes up the other half. SHBG grips testosterone tightly, making it biologically inactive.
This distinction explains why two people with identical total testosterone levels can feel very different. If one person has high SHBG levels, more of their testosterone is locked up and unavailable. A total testosterone test, the most commonly ordered version, measures all three forms combined. The normal range for healthy, non-obese men aged 19 to 39 is 264 to 916 ng/dL, based on harmonized data from over 6,900 men across U.S. and European cohorts. A free testosterone test, which isolates only the unbound fraction, is less commonly ordered but can reveal a clearer picture when total levels don’t match symptoms.
Injectable Testosterone Esters
Most prescription testosterone is chemically modified by attaching a fatty acid chain (called an ester) to slow absorption after injection. Longer chains mean more time between injections. The body gradually strips the ester off, releasing active testosterone into the bloodstream.
Testosterone Cypionate and Enanthate
These are the two most widely prescribed injectable forms and behave almost identically. Both have a half-life of about 173 hours (roughly seven days), which means they’re typically injected every one to two weeks. Cypionate is sold as Depo-Testosterone, while enanthate is marketed as Delatestryl and Xyosted. They produce a characteristic pattern: levels spike within a few days of injection, then gradually decline toward a trough before the next dose. Some people notice mood or energy fluctuations that follow this curve.
Testosterone Undecanoate (Long-Acting Injectable)
Undecanoate has the longest ester chain of the injectables, which dramatically extends its duration. Sold as Aveed in the U.S. and Nebido internationally, it’s given as a 750 mg injection, followed by a second injection four weeks later, then once every 10 weeks after that. Peak concentrations take an average of seven days to reach but can range anywhere from 4 to 42 days. The much longer interval between shots appeals to people who dislike frequent injections, though each dose must be administered in a clinical setting.
Testosterone Propionate (Short-Acting)
Propionate has the shortest ester chain (just three carbons), which means it’s absorbed and cleared quickly. It was widely used in the past but has largely fallen out of favor for adults because it requires injections every two to three days to maintain stable levels. You’ll still see it referenced in older literature and in some compounding pharmacy formulations.
Topical Gels
Gels are the most common non-injectable option. You apply them once daily, usually in the morning, to specific skin sites where the testosterone absorbs steadily throughout the day. This produces more stable blood levels than injections, avoiding the sharp peaks and troughs.
AndroGel comes in two concentrations: a 1% formulation and a 1.62% formulation. The 1% version is applied to the shoulders, upper arms, or abdomen. The 1.62% version goes on the shoulders or upper arms only, not the abdomen. Testim is another common brand, packaged in tubes that deliver 50 mg per application to the shoulders and upper arms. None of these gels should be applied to the genitals.
The main practical concern with gels is skin-to-skin transfer. After application, the treated area can pass testosterone to partners, children, or pets through direct contact. Washing your hands thoroughly and covering the area with clothing reduces this risk significantly.
Transdermal Patches
Testosterone patches, sold under the brand name Androderm, deliver a controlled dose through the skin over 24 hours. They come in four strengths that release approximately 2 mg, 2.5 mg, 4 mg, or 5 mg of testosterone per day. You apply the patch to clean, dry skin on the back, abdomen, upper arms, or thighs, rotating sites to avoid irritation. The patch should never go on the scrotum, buttocks, or over bony areas that experience prolonged pressure during sleep or sitting.
Patches produce the most physiologically stable testosterone levels of any delivery method, closely mimicking the body’s natural daily rhythm. The tradeoff is skin irritation at the application site, which is common enough that some people switch to gels or injections after trying patches.
Subcutaneous Pellets
Testopel pellets are small, rice-grain-sized implants placed under the skin (usually in the hip or buttock area) during a brief in-office procedure. A standard dose of 800 mg, divided across multiple pellets, releases testosterone at a steady rate of about 1.3 mg per pellet per day for the first three months. The effective duration is roughly six months before symptoms of low testosterone return and re-implantation is needed.
Pellets offer the longest hands-off experience of any testosterone format. Once they’re placed, there’s nothing to remember daily or weekly. The main drawback is pellet extrusion, where one or more pellets work their way out through the skin before fully dissolving. This happened after about 3.6% of procedures in one study of 756 implantations, and when multiple pellets extruded, the effective duration shortened noticeably.
Oral Testosterone
Oral testosterone has historically been limited by poor absorption and liver strain, but a newer formulation called Jatenzo (oral testosterone undecanoate) addresses both problems. It uses a specialized delivery system that routes absorption through the lymphatic system instead of passing directly through the liver. The starting dose is one 158 mg capsule taken twice daily with a normal meal containing 15 to 45 grams of fat. Unlike older oral formulations that required high-fat meals to absorb properly, Jatenzo works with a typical meal.
Nasal Testosterone
Nasal testosterone gel, sold as Natesto, is applied inside the nostrils using a pump dispenser. It’s absorbed through the nasal lining and enters the bloodstream without passing through the digestive system or liver. The practical requirements are specific: after pumping the gel into each nostril, you press your nostrils together and lightly rub them, then avoid blowing your nose or sniffing for one hour. It’s dosed three times daily, which is more frequent than other options but avoids the skin-transfer concerns of topical gels and the discomfort of injections.
Comparing Delivery Methods
The choice between testosterone types usually comes down to lifestyle preferences, how well you tolerate peaks and troughs, and how often you’re willing to think about your treatment.
- Most stable levels: Patches and pellets deliver the steadiest day-to-day testosterone, with gels close behind.
- Least frequent dosing: Pellets (every 6 months) and injectable undecanoate (every 10 weeks) require the fewest doses per year.
- Most flexibility: Gels and nasal formulations can be stopped and cleared from the body quickly if side effects develop, since there’s no depot of testosterone sitting in muscle or under the skin.
- Lowest cost: Generic testosterone cypionate and enanthate injections are typically the least expensive options, which is one reason they remain the most popular choice.
Each format delivers the same hormone. The differences are entirely about how it gets into your bloodstream, how long it stays active, and what fits your routine.