Hand hygiene, skin prep, needle selection, IM vs SubQ, sharps disposal, and infection warning signs — the fundamentals of safe self-injection.
The fundamentals of aseptic injection technique are well established in nursing and harm-reduction literature. This page summarises those fundamentals for educational reference. It is not a clinical training resource, not a recommendation to self-inject anything, and not a substitute for instruction from a qualified clinician.
Wash your hands with soap and warm water for 20 seconds before you touch anything in your injection setup. Alcohol hand gel is a second-best fallback when soap isn't available. Dry on a clean towel or air-dry — wet hands re-contaminate quickly.
If you're handling vials, ampoules, or syringes that came out of sterile packaging, your hands are the most likely source of contamination. Treat them accordingly.
Single-use wipes only. Re-using a wipe defeats its purpose.
Two needles per injection is standard practice: a larger-gauge draw needle for pulling the dose out of the vial (fast, less effort), and a smaller-gauge inject needle for the actual shot (less tissue trauma).
Rough guide:
| Purpose | Gauge | Length | Notes |
|---|---|---|---|
| Drawing from a vial | 18–21 G | 1–1.5" | Speed matters, sharpness doesn't |
| Intramuscular (glute, ventroglute, thigh) | 22–25 G | 1–1.5" | Length depends on body fat at site |
| Intramuscular (deltoid) | 23–25 G | 1" | Smaller muscle, shorter needle |
| Subcutaneous | 27–31 G | 5/16–1/2" | Insulin-style pin into fatty tissue |
Always swap to a fresh inject needle after drawing. The draw needle is blunted by passing through the rubber stopper and will hurt more going in.
Intramuscular (IM) deposits the oil into muscle tissue. The depot releases over days. This is the traditional route for testosterone esters and most oil-based compounds.
Subcutaneous (SubQ) deposits into the fatty layer just under the skin. Release is slower and steadier, peaks are lower, and many people find injections less painful. Most modern testosterone protocols can be run SubQ effectively, and many peptides are SubQ by default.
Neither is universally "better." SubQ produces flatter curves at the cost of more frequent, smaller injections; IM tolerates larger, less frequent doses.
Aspiration — pulling back on the plunger before injecting to check for blood — was standard teaching for decades. Modern guidelines have largely dropped the requirement for routine IM injections at recommended sites, on the grounds that the major vasculature in those sites is small enough that intravascular hits are clinically insignificant, and aspiration increases pain and time.
The exception is dorsogluteal injections, where larger vessels and the sciatic nerve are nearby — aspirating remains a reasonable precaution if you use that site. Ventroglute, vastus lateralis and deltoid are generally aspiration-optional.
If aspirating gives you peace of mind, do it. It is not dangerous, just usually unnecessary.
Used needles go into a rigid, puncture-proof sharps container. Not a plastic bottle, not the household bin, not a bag. Pharmacies in most jurisdictions exchange full containers for empty ones. Some councils run dedicated collection programmes.
Never recap a needle by holding the cap in one hand and the syringe in the other — this is how needlestick injuries happen. If you must recap, use the one-handed scoop technique (rest the cap on a flat surface and slide the needle into it).
The vast majority of injections produce nothing more than a small, fading sore spot. Watch for:
Any combination of these warrants a medical review. Cellulitis caught early is a course of oral antibiotics. Cellulitis caught late is a hospital admission.
Wash. Wipe. Two needles. Right site, right depth. Sharps box. Pay attention to anything that doesn't heal normally. That's the whole curriculum.
DoseCurve is an educational tool. Nothing on this site is medical advice. Always consult a qualified clinician before starting, changing or stopping any protocol.