Testosterone injection methods compared: what TikTok gets right and wrong

What did @trtclinic1 actually say?

The video is short on words. The creator holds up two syringes and says: "This is the modern method. This is the old school method." That's essentially the entire claim. Without labeling the syringes on screen or naming injection routes, the video implies one delivery method is superior to the other based on its age classification alone. No clinical rationale is offered, no dosing context, no patient profile. The argument is entirely framed around novelty versus tradition, which is a weak basis for any medical comparison.

The most reasonable interpretation, based on standard TRT clinic content, is that the "modern method" refers to subcutaneous (subQ) injection using a short, fine-gauge needle, and the "old school method" refers to intramuscular (IM) injection using a longer needle. That reading shapes the rest of this analysis, though the video itself never confirms it.

Does the science back this up?

Subcutaneous testosterone injection is not fringe science, but calling it definitively "modern" or superior is an oversimplification that the evidence does not fully support. Both routes produce therapeutic testosterone levels in most patients. The real differences are more nuanced than a generational label suggests.

A 2017 study by Olsson et al. in the Journal of Clinical Endocrinology and Metabolism found that subcutaneous testosterone cypionate produced stable serum levels with less peak-and-trough variation compared to standard IM dosing schedules. That is a legitimate advantage. However, a 2021 review by Giltay and colleagues in Andrology noted that IM injection remains the best-studied delivery route for TRT, with decades of pharmacokinetic data, and that subQ absorption can vary more between individuals, particularly in patients with higher body fat percentages. Calling IM "old school" implies it is obsolete. The pharmacology does not support that conclusion.

What did they get wrong (or right)?

Here is what they got right: subcutaneous injection has genuine clinical advantages for many patients. Smaller needle gauge, less injection site discomfort, and more frequent low-dose scheduling that can reduce hormonal swings are all real benefits documented in the literature. Clinicians at TRT-focused practices have increasingly adopted subQ protocols for these reasons, and patient preference data supports it.

Here is what they got wrong: framing this as "modern versus old school" implies IM injection is outdated or inferior by default. That is misleading. IM remains appropriate for certain testosterone esters, specific patient populations, and clinical contexts where absorption consistency is a priority. A 2020 paper by Spratt et al. in Sexual Medicine Reviews specifically cautioned against blanket subQ recommendations without individualized assessment.

The bigger problem is what the video does not say. No information about needle sizes, testosterone ester type, injection frequency, or patient suitability is provided. A viewer who takes "this is the modern method" at face value and attempts to change their own injection technique without clinical guidance could run into real problems, including inconsistent absorption or improper technique.

What should you actually know?

Both intramuscular and subcutaneous testosterone injections are legitimate, clinically used delivery routes with real trade-offs. Neither is universally superior. The right method depends on the specific testosterone formulation being used, the patient's body composition, injection frequency, and personal tolerance for the procedure.

Subcutaneous injection works well with testosterone cypionate and enanthate on frequent low-dose schedules, typically two to three times per week, because the slower subQ absorption complements smaller volumes. Intramuscular injection is still preferred in many clinical protocols, particularly for longer dosing intervals where predictable peak levels matter.

If you are on a TRT program and considering switching injection methods, that conversation belongs with your prescribing clinician, not a TikTok video. Changing your injection route without adjusting dose timing or volume can shift your hormone levels in ways that affect how you feel and your lab results. No 15-second video is sufficient guidance for that decision.