Why does an injection sting or burn?

Research on injected medicines points to several things that make a shot hurt: how acidic the liquid is, its temperature, how fast it goes in, and preservatives such as the benzyl alcohol in bacteriostatic water, which is mildly acidic at roughly pH 5.7. Injecting through rubbing alcohol that has not dried is another known cause of extra stinging. None of this has been tested on the compounds this site tracks, only on injected medicines in general. So treat it as the best explanation we have, not a proven finding for any one peptide. Full detail at /injecting.

Full injecting guide: sites, needles, rotation, safety

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of injecting: sites, needles and safety. Subcutaneous vs intramuscular, site rotation, lipohypertrophy, needle length and gauge, vial hygiene at injection time, travel syringes, scar tissue, and when to stop and see a clinician. Full walkthrough at /injecting.