TRT on TikTok: separating real therapy from bro-science

What did @daviddemesquita actually say?

The creator laid out a pros-and-cons case for subcutaneous (SQ) versus intramuscular (IM) testosterone injections. On the plus side, he said SQ produces "a little bit less scar tissue" and is "technically more stable" because "the half life is slightly longer." He described IM injections as peaking higher and dropping faster. On the downside, he flagged volume as the key limitation, noting that 1-2mL of oil injected subcutaneously risks "severe irritation." He closed by saying he personally prefers IM using an insulin needle. This is practical, experience-based advice, not a clinical recommendation, which matters when evaluating it.

The framing is mostly reasonable, but the half-life explanation deserves closer scrutiny because it conflates absorption rate with half-life in a way that could mislead viewers trying to plan injection frequency.

Does the science back this up?

Partially, yes. The absorption-rate difference is real. The half-life framing is where things get slippery.

A 2017 study by Olsson et al. in the Journal of Clinical Endocrinology and Metabolism compared SQ and IM testosterone undecanoate and found measurable pharmacokinetic differences between routes, with SQ producing a slower absorption curve. For testosterone cypionate and enanthate, the evidence base is thinner. A 2012 study by Kaminetsky et al. in Journal of Sexual Medicine found SQ testosterone cypionate produced stable serum levels with lower peak concentrations, which supports the "more stable" claim.

However, the term "half-life" refers specifically to the time it takes the body to eliminate half the drug after absorption, and that is determined by the ester, not the injection route. What changes with SQ is the absorption rate, not the elimination half-life. These are related but not the same thing, and mixing them up can cause real confusion about how often someone needs to inject.

On scar tissue, frequent IM injections are well-documented to cause local tissue changes over time. SQ injections into adipose tissue do distribute mechanical stress differently, so the claim has biological plausibility, though direct comparative scar tissue data in TRT populations is sparse.

What did they get wrong (or right)?

Credit where it is due: the volume-irritation point is accurate and underappreciated. Subcutaneous tissue has limited capacity for oil-based vehicles. A 2020 review by Spratt et al. in Andrology noted that SQ injection of oil-based testosterone is generally well-tolerated at low volumes but that larger volumes increase the risk of local reactions including induration and granuloma formation. Flagging this is genuinely useful for a TRT audience.

The scar tissue claim is reasonable but probably overstated as a clean "advantage." IM injection technique, specifically using appropriately sized needles and rotating sites, largely mitigates scar tissue risk. Presenting reduced scar tissue as an inherent SQ benefit without that caveat is a bit one-sided.

The half-life explanation is the weakest part. He says IM "reduces down the half life essentially," but this is imprecise. Testosterone cypionate has a half-life of roughly 8 days regardless of route. What IM changes is the absorption peak. This distinction matters practically: someone hearing "longer half-life" from SQ might wrongly conclude they can inject less frequently, which is not supported by the pharmacokinetic data for standard TRT esters.

What should you actually know?

If you are on TRT and curious about injection route, here is what the evidence actually supports. First, SQ testosterone cypionate at low volumes (typically under 0.5mL) produces flatter serum testosterone curves with lower peak-to-trough variation compared to IM, which some patients find improves mood and energy consistency. This is backed by real data, not just anecdote.

Second, the ester determines elimination half-life. Testosterone cypionate is testosterone cypionate whether you inject it in your glute or your belly fat. What differs is how fast it gets into circulation, not how fast your body clears it once it is there.

Third, volume limits are real. Daily low-dose SQ works because the volumes stay small. Trying to push a standard weekly 1mL dose subcutaneously is where problems start, and the creator is right to flag this from personal experience.

Finally, neither route is universally superior. Route choice should factor in injection volume, individual tissue tolerance, injection frequency, and personal preference. A prescribing clinician is the right person to help you decide, not a TikTok comment section.