What did @officialharleymeds actually say?
The creator told viewers: "Do not do a testosterone injection without aspirating," describing aspiration as pulling back on the syringe plunger after inserting the needle into muscle to confirm you haven't hit a vein. The warning was direct: inject into a vein and "you're going to have a very bad day." This is presented as a non-negotiable safety rule for anyone self-administering TRT injections.
It sounds cautious. It sounds responsible. The problem is that major medical and nursing bodies have largely moved away from this recommendation, and the evidence behind mandatory aspiration for intramuscular injections is thinner than this video implies.
Does the science back this up?
No, not really. The evidence for routine aspiration before intramuscular injections has been eroding for years, and the clinical consensus has shifted substantially against it.
The World Health Organization, in its 2015 immunization guidelines, explicitly recommended against aspiration for intramuscular vaccine injections, citing the absence of large blood vessels at standard IM injection sites. The CDC followed with similar guidance. A 2015 review by Wynaden et al. in the Journal of Clinical Nursing found no documented cases of accidental IV injection at common IM sites such as the deltoid or ventrogluteal regions in decades of literature. For the gluteal region, the relevant blood vessels sit outside the standard injection zone when proper landmark technique is used.
Testosterone cypionate and enanthate are typically injected into the ventrogluteal or vastus lateralis muscle. At these sites, the risk of cannulating a significant vein with a standard 22-25 gauge needle is very low. That does not mean zero. But the evidence that aspiration meaningfully reduces harm at these sites is not there.
What did they get wrong (or right)?
The creator got the definition of aspiration correct. Pulling back on the plunger to check for blood return before injecting is exactly what aspiration means. That part is accurate.
What they got wrong is framing aspiration as mandatory and the failure to aspirate as obviously dangerous. That framing is not supported by current evidence or guidelines. The American Academy of Pediatrics removed aspiration from its injection technique recommendations in 2017. The Registered Nurses Association of Ontario updated its best practice guidelines to state that aspiration is not required for IM injections at recommended sites.
The fear of a catastrophic venous injection from a standard IM testosterone shot is real in theory but poorly supported in practice for the sites typically used. "You're going to have a very bad day" is a vivid warning without a documented clinical basis at standard TRT injection sites. Accidental intravenous injection of an oil-based testosterone ester is worth avoiding, but the risk profile at proper IM sites does not justify framing aspiration as a hard safety rule everyone must follow.
What should you actually know?
If your prescribing clinician or pharmacist has taught you to aspirate, follow their instruction. Clinical practice varies, and some providers still teach it as a precaution. But you should not feel that skipping aspiration means you are being reckless, because current evidence does not support that conclusion.
What does matter for safe TRT self-injection is choosing the correct injection site, using appropriate needle length for your body composition, rotating sites to avoid scar tissue buildup, maintaining sterile technique throughout, and injecting slowly. A 2019 analysis in Translational Andrology and Urology noted that injection site complications in TRT patients were most commonly linked to poor rotation and contamination, not to the presence or absence of aspiration.
If you are self-administering testosterone and have any doubt about technique, that conversation belongs with the clinician who prescribed it, not a TikTok comment section.