Edema is fluid build-up with many causes, such as sitting still for long periods, salty food, pregnancy, some medicines, or heart, kidney and liver problems, and it often improves when the cause is treated.[1] Lymphedema happens when the lymphatic system does not work properly, most often after cancer treatment, and is long-term: it cannot be cured, but symptoms can usually be controlled.[2] A doctor needs to find the cause.
Side by side
| Edema (oedema) | Lymphedema | Lipedema | |
|---|---|---|---|
| What it is | Fluid build-up in tissues[1] | Swelling because lymph does not drain properly[2] | Abnormal build-up of fat, mainly in legs[3] |
| Common causes | Sitting or standing still, salt, pregnancy, medicines, vein, heart, kidney or liver problems[1] | Cancer surgery or radiotherapy, infection, injury, immobility; rarely genetic[2] | Not fully understood; more common in women[3] |
| Usual pattern | Often both legs; may come and go | Often one limb or one area; may start soft and come and go, later firmer[2] | Both sides equally; feet usually spared[3] |
| Skin | Usually normal | Can thicken, form folds or leak fluid over time; infections more likely[2] | Often tender, bruises easily |
| Treatment | Treat the cause; raise legs, move, reduce salt[1] | Compression, skin care, exercise, specialist massage[2] | Healthy eating, activity, compression; specialist care[3] |
More about edema
Most swollen ankles are edema caused by everyday factors such as long periods of sitting or standing, hot weather, salty food, being overweight or pregnant, or medicines such as some blood pressure tablets, contraceptive pills and steroids.[1] Less often, it reflects a blood clot, infection, or a heart, kidney or liver problem, which is why persistent swelling should be checked.[1]
More about lymphedema
Secondary lymphedema follows damage to lymph nodes or vessels. After breast cancer, about 1 in 5 people develop it, with a higher rate after full underarm node removal than after sentinel node biopsy (about 20% vs 6%).[4] Early lymphedema can be soft, leave a dent when pressed and come and go; later it may become firmer.[2] Cellulitis, a skin infection, is its most common complication.[2]
How the cause is found
A GP will ask about your history (for example cancer treatment, new medicines, travel), examine the swelling and may arrange blood tests or scans to check the heart, kidneys, liver or veins, or to rule out a blood clot. If lymphedema is likely, they may refer you to a specialist lymphoedema service.[2]
When to get help
Get medical help first if…
- Call 999 (or your local emergency number) if swelling comes with chest pain or tightness, breathlessness, coughing up blood, or feeling faint. These can be signs of a blood clot in the lungs.[1]
- Get an urgent GP appointment or call 111 if swelling is in one leg only with no clear cause, is sudden, painful or getting worse, the skin is red or hot, or you have a high temperature.[1]
- See a GP if swelling in both legs has not improved after a few days, or you have a heart, kidney or vein condition.[1]
Common questions
Can edema turn into lymphedema?
Long-standing swelling can put extra strain on the lymphatic system, but the two usually have different causes. A doctor can assess which you have.
Keep reading
Sources
We checked each source on 12 October 2026. Numbers in the text link to this list.
This guide is general information, not medical advice. It has not been reviewed by a doctor. Read our medical disclaimer.