Most men on testosterone cypionate inject once a week or once every two weeks. The FDA-approved label recommends a dose of 50 to 400 mg every two to four weeks, but current clinical practice has shifted toward more frequent, smaller injections to keep blood levels stable. The Endocrine Society guidelines recommend either 75 to 100 mg weekly or 150 to 200 mg every two weeks as the standard approach.
Which schedule works best depends on how your body responds, but the trend in testosterone replacement therapy is clearly toward more frequent dosing. Here’s why that matters and what to expect from each approach.
Why Injection Frequency Matters
Testosterone cypionate has a half-life of about eight days. That means roughly half the testosterone from a single injection is gone after one week. If you inject a large dose every two weeks, your levels peak sharply in the first few days, then steadily drop. By the end of the second week, many men fall below the therapeutic range and start feeling it.
This pattern creates what’s often called the “roller coaster” effect: alternating periods of feeling good and a return to baseline symptoms like low energy, reduced libido, and mood changes that correspond directly to the rise and fall of testosterone in your blood. The larger the dose and the longer the gap between injections, the more dramatic these swings become.
Beyond how you feel day to day, those high peaks carry physiological consequences. Supraphysiological spikes in testosterone stimulate your body to produce more red blood cells in a dose-dependent way, raising your hematocrit (the percentage of red blood cells in your blood). Injectable testosterone is already associated with a greater risk of elevated hematocrit compared to other formulations, and that risk is driven specifically by the transient peaks that large, infrequent doses create. Testosterone also converts to estradiol through an enzyme called aromatase, and men on injectable therapy see more significant increases in estradiol than men on topical formulations, likely because of those same concentration spikes.
Every Two Weeks vs. Weekly Injections
The every-two-week schedule (typically 150 to 200 mg per injection) remains common because it’s convenient and matches the FDA label. For some men, it works fine. But clinically, the Endocrine Society recommends checking your testosterone level midway between injections. If that mid-interval reading falls below 350 ng/dL or rises above 600 ng/dL, your dose or frequency needs adjusting. Many men on a biweekly schedule find their trough levels dip too low.
Weekly injections of 75 to 100 mg produce more physiological and predictable testosterone levels. You still get a small peak and trough, but the difference between them is much narrower. Most men on a weekly schedule report more consistent energy, mood, and libido throughout the week compared to the biweekly approach. This is now the preferred schedule in most TRT-focused clinical practices.
Twice-Weekly and More Frequent Protocols
Some men split their weekly dose into two injections, typically every 3.5 days. If your weekly dose is 100 mg, you’d inject 50 mg on Monday morning and 50 mg on Thursday evening, for example. This flattens the curve even further, producing the most stable blood levels possible with cypionate. Men who are sensitive to estrogen-related side effects (water retention, mood changes, nipple sensitivity) or who tend to run high hematocrit levels often do better on this schedule because peak concentrations stay lower.
There’s no strong clinical trial comparing twice-weekly to weekly head to head, but the pharmacokinetic logic is straightforward: smaller, more frequent doses mean smaller peaks and higher troughs. For most men, though, once a week provides a good balance between stability and convenience.
Subcutaneous vs. Intramuscular Injection
Testosterone cypionate is FDA-approved for deep intramuscular injection into the glute muscle, but subcutaneous injection (into the fat layer just under the skin, usually in the abdomen or thigh) has become widely used in clinical practice. Subcutaneous injections use a smaller needle, are less painful, and are easier to self-administer.
Research in transgender men found that weekly subcutaneous doses of 50 to 100 mg reliably achieved therapeutic testosterone levels between 348 and 1,197 ng/dL. A suggested starting dose for subcutaneous injection is 75 mg per week, which tends to be slightly lower than a typical intramuscular dose because absorption characteristics differ somewhat. The subcutaneous route pairs especially well with more frequent injection schedules since the smaller needle makes twice-weekly or even every-other-day dosing much more practical.
How to Find Your Ideal Schedule
Your optimal frequency is something you and your prescriber dial in over time using blood work and symptoms. The standard process looks like this: start at a typical dose and frequency (often 100 mg weekly intramuscular, or 75 mg weekly subcutaneous), then check your testosterone level midway between injections after four to six weeks. If your mid-interval level sits between 350 and 600 ng/dL and you feel good, you’re likely in the right spot.
If your trough is too low and you’re dragging in the days before your next injection, increasing the frequency (going from weekly to twice weekly, for instance) is often a better first step than increasing the total weekly dose. A higher dose raises the peak without doing much for the trough and amplifies the side effects tied to those peaks.
Body size plays a role in how quickly you metabolize testosterone. Larger men (measured by body surface area) tend to clear it faster and may need slightly higher doses or more frequent injections. Age also matters: the effect of testosterone on red blood cell production is more pronounced in older men, which is another reason to favor smaller, more frequent doses as you get older. Interestingly, SHBG levels, which many online forums emphasize as a key factor in choosing injection frequency, did not significantly predict the optimal interval between injections in clinical research.
Common Schedules at a Glance
- Every two weeks: 150 to 200 mg per injection. Convenient but produces the widest swings in blood levels. Most likely to cause roller-coaster symptoms.
- Once weekly: 75 to 100 mg per injection. The most common schedule in current clinical practice. Good balance of stability and simplicity.
- Twice weekly (every 3.5 days): Total weekly dose split in half. Flattest blood levels, lowest peaks. Preferred for men prone to elevated hematocrit or estrogen-related side effects.
Regardless of which schedule you start with, the frequency is always something that can be adjusted. Blood work taken at the right time point (midway between injections) gives you and your provider the clearest picture of whether your current protocol is working or needs a change.