Testosterone replacement therapy (TRT) uses several formulations of testosterone, but the most common by far are two injectable esters: testosterone cypionate and testosterone enanthate. Beyond injections, options include topical gels, adhesive patches, implantable pellets, and newer oral capsules. Each delivers the same hormone but differs in how often you use it, how stable your levels stay, and what side effects to watch for.
Injectable Testosterone: Cypionate and Enanthate
Injections are the most widely prescribed form of TRT, largely because they’re effective and inexpensive. The two standard options are testosterone cypionate and testosterone enanthate. They’re nearly interchangeable in practice. Cypionate has a half-life of about eight days, while enanthate’s half-life falls in the seven-to-nine-day range. Both are typically dosed at 50 to 400 mg every two to four weeks, though many prescribers now favor smaller, more frequent injections (weekly or even twice weekly) to keep blood levels steadier.
One practical difference between the two is the carrier oil. Testosterone cypionate is suspended in cottonseed oil, while enanthate uses sesame seed oil. If you have an allergy to either oil, your doctor will prescribe the other ester. Both can be injected into muscle or under the skin (subcutaneously), and many people on TRT learn to self-inject at home.
The main drawback of injectable esters is that testosterone levels rise sharply after the injection, then gradually fall before the next dose. Some people feel these swings as changes in energy, mood, or sex drive in the days before their next shot. Splitting the dose into more frequent, smaller injections helps flatten that curve.
Testosterone Propionate
A third injectable ester, testosterone propionate, has a much shorter duration of action and needs to be injected every two to three days. That frequency makes it impractical for most people on long-term TRT, so it’s rarely used today. You’ll mostly encounter it in older medical literature or in niche clinical situations.
Topical Gels and Patches
Transdermal testosterone, meaning it absorbs through the skin, is the second most popular delivery method. It comes in two main forms: gels and patches. A standard testosterone patch delivers about 5 mg per day and is typically applied at night to mimic the body’s natural rhythm of higher morning testosterone. Gels come in a 1% concentration (and a higher 1.62% version) and are usually applied in the morning.
The biggest advantage of topical testosterone is steady absorption. Instead of the peak-and-valley pattern of injections, gels and patches provide a more consistent daily level. The tradeoff is that you have to apply them every single day, and there’s a real risk of transferring testosterone to other people through skin contact. After applying gel, you should wash your hands thoroughly with soap and water and cover the application site with clothing once it dries. This is especially important around pregnant women and children, who can absorb testosterone through casual skin contact and experience harmful effects.
Some people also find that gels irritate the skin or that patches leave red marks or cause itching at the application site. Absorption can vary depending on body composition and skin type, which sometimes makes it harder to dial in the right dose compared to injections.
Implantable Pellets
Testosterone pellets (sold under the brand name Testopel) are small, rice-grain-sized implants placed under the skin during a brief in-office procedure. The pellets dissolve slowly over two to six months, with most people returning for replacement every three months. The number of pellets implanted per session varies based on your blood levels and individual needs.
Pellets offer the most hands-off experience of any TRT method. Once they’re in, you don’t need to think about daily applications or weekly injections. The downside is that if your dose turns out to be too high or you have side effects, you can’t simply stop or adjust mid-cycle the way you can with other forms. You also need a minor procedure each time, which carries a small risk of infection or pellet extrusion (where a pellet works its way back out through the skin).
Oral Testosterone Capsules
For decades, oral testosterone was considered impractical because older formulations were broken down by the liver before they could reach the bloodstream, which limited effectiveness and raised concerns about liver damage. That changed with the FDA approval of testosterone undecanoate capsules, sold under the brand name Jatenzo. This formulation is absorbed through the lymphatic system rather than passing directly through the liver, which largely avoids those older problems.
Oral testosterone undecanoate must be taken with food to absorb properly. It’s typically dosed twice daily, which some people find convenient compared to injections but less convenient than a once-daily gel. It’s also generally more expensive than injectable testosterone, which limits its use.
How Formulations Compare in Practice
- Cost: Injectable cypionate and enanthate are the least expensive options. Gels, patches, pellets, and oral capsules all cost more, sometimes significantly.
- Level stability: Pellets and daily gels tend to produce the most stable blood levels. Injections cause more fluctuation unless given frequently. Oral capsules fall somewhere in between.
- Convenience: Pellets require the least day-to-day effort (every three months). Injections need weekly or biweekly attention. Gels and oral capsules require daily use.
- Transfer risk: Only topical gels and creams carry a risk of exposing others to testosterone through skin contact. All other methods keep the hormone contained.
Monitoring on TRT
Regardless of which formulation you use, TRT requires regular blood work. The Endocrine Society recommends confirming low testosterone with at least two separate blood draws before starting treatment, and ongoing monitoring once you begin. One key value your doctor will track is hematocrit, a measure of red blood cell concentration. Testosterone stimulates red blood cell production, and if hematocrit rises above 54%, your dose may need to be reduced or you may need a blood draw (therapeutic phlebotomy) to bring it back down. The American Urological Association recommends checking hematocrit every 6 to 12 months.
Your doctor will also monitor your testosterone levels to make sure they’re in the target range and may adjust your dose or switch formulations if one method isn’t working well. Some people try multiple delivery methods before settling on the one that fits their body, schedule, and budget.