TikTok needle advice for TRT shots needs more context

What did @harleymeds.com actually say?

The creator recommended a "25 gauge, 5-8 inch needle" for intramuscular TRT injections into the upper outer glute or ventroglute, and a "half inch, 29 or 31 gauge needle" for subcutaneous injections. They framed this as personal experience over five years, not a clinical directive. That framing matters, and it's worth acknowledging upfront.

The video is practical, not alarmist. It covers two common injection routes, names specific anatomical sites, and invites community discussion. But there is a significant error buried in the recommendation that could cause real harm if someone follows it literally, and that needs to be addressed directly.

Does the science back this up?

Partly, yes. The subcutaneous recommendation is solid. A 29 or 31 gauge, half-inch needle for subcutaneous testosterone injections is well-supported in clinical literature. Spratt et al. (2017, Journal of Clinical Endocrinology and Metabolism) confirmed that subcutaneous testosterone cypionate produces stable serum levels comparable to intramuscular delivery, and fine-gauge, short needles are standard for that route.

For intramuscular injections, the 25 gauge recommendation is reasonable. Studies like Malkin et al. (2004, Heart) and standard pharmacy guidance suggest 23-25 gauge needles for IM testosterone to balance ease of injection with manageable draw time. The ventroglute as a preferred IM site also has clinical backing. Nicoll and Hesby (2002, Journal of Advanced Nursing) identified the ventroglute as the safest IM injection site due to muscle mass and distance from major nerves.

The gauge advice is defensible. The length advice, however, is not.

What did they get wrong (or right)?

The creator says "5-8 inch needle" for intramuscular injection. This is almost certainly a spoken error. They likely meant 5/8 of an inch, written as 0.625 inches, which is a real needle length used for IM injections in leaner individuals. A literal 5 to 8 inch needle does not exist in clinical practice for this purpose, and injecting one would be catastrophically dangerous.

This is a speech artifact, not malicious misinformation, but it illustrates why casual TikTok advice on injection technique is risky. A viewer new to TRT who mishears or misreads that fraction could be genuinely confused. Standard IM needle lengths for glute injections range from 1 inch to 1.5 inches depending on body composition, per the CDC's injection safety guidelines. For heavier patients, 1.5 inches is often necessary to reach muscle tissue. A 5/8-inch needle in a glute with significant adipose tissue may not reach muscle at all, which can cause oil embolism risk or sterile abscess formation.

They got the injection sites right. Upper outer glute and ventroglute are both appropriate, clinically accepted sites. That part deserves credit.

What should you actually know?

Needle selection for TRT injections is not one-size-fits-all, and that is the most important thing missing from this video. Body composition directly affects whether a given needle length reaches muscle tissue. The CDC's 2007 injection technique guidelines and updated recommendations from the World Health Organization specify that needle length for IM injections should be chosen based on patient weight and site-specific tissue depth.

For a lean individual, a 1-inch, 25-gauge needle into the ventroglute is reasonable. For someone with higher body fat, 1.5 inches may be necessary. Subcutaneous injections are genuinely gaining traction in clinical settings because they reduce injection anxiety, allow for finer needles, and Spratt et al. (2017) showed comparable pharmacokinetics for cypionate. Some practitioners now prefer the subcutaneous route specifically because it is more forgiving of minor technique variation.

The bottom line: verify needle length with your prescribing provider based on your specific anatomy. Do not crowdsource this from TikTok comments, including this one.

Our verdict

The creator gets credit for knowing their injection sites and for correctly recommending subcutaneous needle specs. The 25-gauge gauge recommendation for IM is also reasonable. But the "5-8 inch" phrasing is a genuine error that could confuse new TRT users, and there is no acknowledgment that needle length must be individualized by body composition. This is a 60% accurate video with one potentially consequential mistake. Treat it as a starting point for a conversation with your doctor, not a protocol.