Lipohypertrophy is a rubbery, hardened thickening of the fat under the skin from injecting the same spot repeatedly. Not medical advice.
Key points
- 01What lipohypertrophy feels like. A rubbery, firm lump or a flat thickening under the skin, sometimes with a sunken surface. It is usually painless and easier to feel than to see. It typically appears at frequently used spots, like the same point on the abdomen or thigh.
- 02How it differs from a bruise. A bruise is discoloured (blue, green, yellow), superficial, and fades over one to two weeks. Lipohypertrophy is a change in the deeper fat tissue, usually skin-coloured, firm to the touch, and persists for weeks to months.
- 03Why it disrupts absorption. Scarred, hardened fat has a poorer blood supply. Injecting into it leads to variable and often reduced uptake of the medication, per diabetes-care guidance, which can cause unpredictable blood-glucose readings with insulin.
- 04Preventing it by rotating sites. Rotate systematically both between areas (abdomen, thigh) and within an area. Place each injection at least 1 inch (2 to 3 cm) from the last, and use a fresh needle for every injection.
- 05If lipohypertrophy is already present. Stop injecting into the affected spot and switch to unaffected tissue. Many hardened areas resolve over weeks to months once consistently rested. Ask your prescriber whether the dose needs adjusting when you move to healthy tissue.
Pre-injection checklist
- ✓Feel over every site you have used about once a week, ideally lying down with the abdomen relaxed.
- ✓Look for a rubbery, slightly raised or sunken patch that feels firmer than the surrounding tissue. Lipohypertrophy is often easier to feel than to see.
- ✓Compare a suspicious area with unused tissue on the opposite side to register the difference by touch.
- ✓Do not inject into a hardened area. Medication absorbs unreliably from damaged tissue.
- ✓Keep a simple dosing log so rotation across areas follows a plan rather than memory.
After the injection
- Use a new, sterile needle for every injection. Reused, blunted needles damage tissue more and promote lipohypertrophy.
- Record the date and exact site after each dose so the next injection lands on fresh tissue.
- Check used sites regularly by feeling, not just looking.
Common mistakes
- A hardened area that is warm, red, tender, or progressively swollen, possible infection rather than lipohypertrophy.
- Unexplained swings in blood-glucose readings with insulin, a clue to impaired absorption from damaged tissue.
- A new or rapidly growing lump that remains unclear, have it assessed by a clinician.
- Difficulty breathing, swelling of the face, throat, or tongue, or hives, signs of serious allergic reaction.
Frequently asked questions
What is lipohypertrophy?+
Lipohypertrophy is a rubbery thickening of the subcutaneous fat caused by repeated injections into the same spot and by reusing needles. It is usually painless, firm to the touch, and can make absorption of insulin or GLP-1 medications unreliable.
How do I tell lipohypertrophy apart from a bruise?+
A bruise is discoloured, superficial, and clears within one to two weeks. Lipohypertrophy is a firm, skin-coloured hardening in the deeper fat that lasts weeks to months and is often easier to feel than to see. See our injection-site-bruising post as well.
Does lipohypertrophy go away?+
Often, yes. When the affected spot is consistently rested, hardened tissue frequently resolves over several weeks to months. The key is to stop injecting there and rotate systematically.
How do I prevent lipohypertrophy?+
Rotate sites systematically between and within areas, keep each injection at least 1 inch (2 to 3 cm) from the last, and use a fresh needle for every injection. See our rotating-injection-sites post for a labeled diagram.
Can I inject into a hardened spot if it does not hurt?+
No. Medication absorbs unreliably from lipohypertrophic tissue, which causes swings especially with insulin. Rest the area and switch to unaffected tissue. Discuss any dose adjustment with your prescriber.
Sources
- Frid AH et al. 2016. New Insulin Delivery Recommendations. Mayo Clinic Proceedings 91(9):1231-1255.
- Forum for Injection Technique (FIT). The UK Injection and Infusion Technique Recommendations.
- Gentile S et al. 2016. Lipohypertrophy and insulin: an update. Diabetes Therapy.
- American Diabetes Association. Standards of Care, insulin injection technique.