Starting testosterone therapy involves getting the right blood tests, receiving a clinical diagnosis of low testosterone, choosing a delivery method with your provider, and then following a monitoring schedule to stay safe. The process typically takes a few weeks from first appointment to first dose, and most people notice initial effects within three to six weeks of starting treatment.
Getting Diagnosed With Low Testosterone
The American Urological Association defines low testosterone as a total testosterone level below 300 ng/dL, measured from a morning blood draw. You need at least two separate morning readings below that threshold, because testosterone levels fluctuate throughout the day and peak in the early hours. Other medical societies use cutoffs ranging from 230 to 350 ng/dL, but 300 ng/dL is the most widely applied standard in the U.S.
Low numbers alone aren’t enough. You also need symptoms: low sex drive, fatigue, depressed mood, difficulty building muscle, increased body fat, or problems with erections. A provider will want to rule out other causes for those symptoms first, including thyroid problems, sleep apnea, or medication side effects, before attributing them to testosterone.
Baseline Blood Work Before Treatment
Before you get a prescription, your provider will order a panel of blood tests beyond just testosterone. AUA guidelines recommend checking your hematocrit level (a measure of red blood cell concentration), since testosterone can push this dangerously high. If you’re over 40, you’ll also need a baseline PSA test to screen for prostate issues. Your provider will likely check for signs of breast tissue changes and ask about your family history of prostate cancer, since men with first-degree relatives who had prostate cancer or African American men with a PSA above 3 ng/mL are considered higher risk.
Expect the provider to also ask about your interest in having children. This matters because testosterone therapy suppresses sperm production, sometimes severely, and that conversation needs to happen before you start.
Choosing a Delivery Method
Testosterone comes in several forms, and each involves real tradeoffs in convenience, consistency, and side effects.
- Injections (cypionate or enanthate): The most common starting method. A typical starting dose is 75 mg injected subcutaneously once a week, adjusted based on your blood work. Injections produce the highest peak testosterone levels and are inexpensive, but they create more fluctuation. Some people feel great the day after injecting and sluggish by the end of the week. Injection site soreness and occasional hematomas are common.
- Topical gels: Applied daily to the shoulders, upper arms, or abdomen. About 74 to 87% of men reach normal testosterone levels with gels. They mimic the body’s natural daily rhythm more closely than injections. The main drawback is transference risk: women and children who touch the application site can absorb testosterone through their skin, which can cause hormonal disruption. You need to wash your hands thoroughly and keep the area covered.
- Patches: Applied every 24 to 48 hours, patches bring 77 to 100% of users into the normal range. They’re effective but notorious for causing skin irritation at the application site.
- Subcutaneous pellets: Small pellets implanted under the skin every few months in an office procedure. They provide steady levels and high adherence since you don’t have to remember daily or weekly dosing, but the insertion requires a minor procedure each time.
- Nasal gels and oral capsules: Newer options that require multiple doses per day. They have the lightest impact on the hormonal feedback loop that controls sperm production, making them potentially better for fertility preservation, but the dosing frequency is a dealbreaker for many people.
Short-acting methods (gels, patches, nasal, oral) more closely mimic how your body naturally produces testosterone and tend to suppress fertility less. Long-acting methods (injections, pellets) are more convenient but more likely to push levels above the normal range and shut down natural production more completely.
Fertility: What You Need to Know First
Testosterone therapy can dramatically reduce your sperm count. In men who start standard therapy without any protective measure, the testosterone levels inside the testicles, where sperm are actually made, drop by about 94%. This often leads to temporary infertility and testicular shrinkage.
If you want to have children now or in the future, your provider can prescribe a hormone called hCG alongside testosterone. hCG mimics the natural signal your brain sends to your testicles to produce testosterone locally. At a low dose given every other day alongside therapy, it kept testicular testosterone within 7% of baseline in one study, and at a higher dose it actually increased it by 26%. Research has shown that this approach preserves sperm production at one year of follow-up. Some providers also use hCG in cycles, periodically swapping it in for testosterone to give the reproductive system a chance to recover.
If fertility is important to you, bring this up at your very first appointment. It’s much easier to preserve sperm production from the start than to try to recover it after months of suppression.
Who Should Not Start Testosterone
Testosterone therapy is not safe for everyone. It is contraindicated in men with untreated prostate cancer or breast cancer, since testosterone can fuel the growth of these tumors. Men with poorly controlled heart failure also need careful evaluation, because testosterone increases red blood cell production and fluid retention, which can strain an already weakened heart. High-risk individuals, including African American men and those with a family history of prostate cancer, need thorough screening and closer monitoring if they proceed.
Getting a Prescription: In Person and Online
You can get a testosterone prescription through a primary care doctor, an endocrinologist, or a urologist. Many men start with their regular doctor, who can order the initial blood work and refer to a specialist if needed.
Telehealth is also a legitimate option. The DEA has extended telemedicine prescribing flexibilities through December 31, 2026, allowing practitioners to prescribe controlled substances like testosterone (a Schedule III medication) through video visits without ever requiring an in-person evaluation. Several online clinics specialize in hormone therapy and can coordinate blood work at a local lab, review results over video, and ship medication directly. The same diagnostic criteria apply regardless of whether your visit is in person or virtual: two confirmed low readings plus symptoms.
What to Expect in the First Months
Testosterone doesn’t work overnight, but some effects show up surprisingly fast. Changes in sexual desire and sexual thoughts typically appear within three weeks and plateau around six weeks. Improvements in mood and general quality of life begin in the same three-to-four-week window, though depressive symptoms may take six weeks to start lifting and up to 30 weeks to fully improve. Insulin sensitivity can begin shifting within days.
Body composition changes take longer. Reductions in abdominal fat typically become measurable after about three months and continue improving for up to two years. Muscle strength gains appear between 12 and 20 weeks, stabilize around 6 to 12 months, and can continue marginally beyond that. Changes in erectile function and ejaculation may take up to six months.
The takeaway: give it time. Many people feel a noticeable difference in energy and drive within the first month, but the physical changes that show up in the mirror take three months or more to become apparent.
Ongoing Monitoring and Safety
Starting testosterone is not a one-time event. It requires regular blood work to keep levels in a safe range and catch problems early. The standard schedule looks like this:
- 3 to 6 months after starting: Your first follow-up blood draw to check testosterone levels and hematocrit. For injections, the blood draw should happen midway between doses. If your mid-interval testosterone is above 600 ng/dL or below 350 ng/dL, your provider will adjust the dose. For gels, blood is drawn 2 to 8 hours after application.
- Annually after that: Ongoing checks of testosterone, hematocrit, and (if applicable) PSA to monitor for prostate changes.
The most common lab abnormality on testosterone therapy is a rising hematocrit. A hematocrit above 50% warrants investigation. If it reaches 54%, guidelines call for pausing therapy until levels normalize, then restarting at a lower dose. Your provider may also recommend therapeutic phlebotomy (essentially a blood donation) to bring levels down. This is why skipping follow-up blood work is risky: elevated hematocrit increases the chance of blood clots, and you won’t feel it happening until it’s a problem.
Other side effects to watch for include acne, oily skin, worsening sleep apnea, and breast tenderness. Most of these are dose-dependent, meaning they improve when the dose is dialed back. Testosterone therapy is a process of ongoing adjustment, not a fixed prescription you forget about.