What an injection-site granuloma is, how it differs from a bruise or lipohypertrophy, and when a persistent lump needs a clinician. Not medical advice.
Key points
- 01A granuloma is the body walling something off. A granuloma is a small firm nodule the immune system forms around a substance it treats as a persistent irritant. At an injection site it can appear as a lump that lingers longer than an ordinary reaction.
- 02It is different from a routine post-injection lump. Most lumps after a shot are transient swelling or a bruise that fades within days. A granuloma is firmer and more persistent; our hard-lump guide covers the common short-lived lumps for comparison.
- 03It is not the same as lipohypertrophy. Lipohypertrophy is soft, rubbery fatty thickening from repeatedly injecting the same spot. A granuloma is a distinct firm nodule from an immune response. Our lipohypertrophy guide explains that separate problem.
- 04Poor rotation and technique raise the odds. Repeatedly hitting the same area, or irritation from a substance or additive, can drive nodule formation. Consistent site rotation, covered in our rotation guide, is the main preventive lever you control.
- 05Do not squeeze, dig at, or inject into it. Manipulating a nodule can worsen inflammation, and injecting into altered tissue changes absorption. Choose a clean, unaffected site in your rotation and leave the lump alone.
- 06Persistent, growing, or painful lumps need review. A firm lump that lasts weeks, grows, becomes painful, or shows redness, warmth, or drainage should be assessed by a clinician to distinguish a granuloma from infection or other causes. See our infection red flags guide.
Frequently asked questions
What is an injection-site granuloma?+
A small firm nodule the immune system forms around something it treats as a persistent irritant at the injection site. It tends to last longer and feel firmer than an ordinary post-injection lump. Not medical advice.
How is a granuloma different from lipohypertrophy?+
Lipohypertrophy is soft, rubbery fatty thickening from repeated injections in one spot, while a granuloma is a distinct firm nodule from an immune response. See our lipohypertrophy guide for that condition.
Should I inject into or squeeze a granuloma?+
No. Squeezing can worsen inflammation and injecting into altered tissue changes absorption. Pick a clean, unaffected site in your rotation and leave the nodule alone.
When should a lump be checked by a clinician?+
If it lasts weeks, grows, becomes painful, or shows redness, warmth, or drainage, have it assessed to tell a granuloma from infection or other causes. See our infection red flags guide.