Why does the same injection spot get a lump?

The lump is a buildup of fatty tissue (lipohypertrophy) from hitting the same small patch of skin again and again. A 2026 review that pooled 51 studies of people using insulin found that not rotating spots properly was the biggest measured risk. It came with roughly nine times the odds of a lump compared with proper rotation, a bigger risk than reusing the same needle. The lump itself soaks up medicine more slowly and less evenly than normal skin. 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.