Swollen Feet: Common Causes and Red Flags
Swelling in the feet and ankles (oedema) happens when fluid collects in the tissues. It is often harmless and temporary, but in some cases it signals a problem that needs medical attention.
Common harmless causes
Frequent benign causes include long periods of standing or sitting, hot weather, pregnancy, premenstrual fluid retention, a salty meal, a long flight, and minor foot or ankle injuries. Swelling that affects both feet equally and settles overnight is usually mechanical.
Medical causes
Persistent or one-sided swelling can reflect venous insufficiency, a blood clot (deep vein thrombosis), heart, kidney or liver conditions, lymphoedema, certain medications (some blood-pressure drugs, steroids and hormones), or infection. The NHS highlights that swelling in just one leg, or with pain and redness, needs urgent review for a possible clot.
Home relief
Elevate your legs above heart level, move and walk regularly to pump fluid back, reduce dietary salt, stay hydrated, and consider graduated compression socks for standing jobs or travel. Avoid sitting or standing still for long stretches.
Warning signs
When to see a doctor
Book an appointment for swelling that does not settle with elevation, keeps recurring, affects only one side, or comes with skin changes or a wound. Bring a list of your medications, as several can cause oedema.
Frequently asked questions
- Why are my feet swollen at the end of the day?
- Gravity pools fluid in the feet during prolonged standing or sitting; it usually settles overnight with elevation.
- When is swollen feet an emergency?
- Sudden one-sided swelling with pain and redness, or swelling with chest pain or breathlessness, needs immediate medical care.
Sources & further reading
- Foot and ankle health, Mayo Clinic
- Foot problems, NHS
- Patient resources, American Podiatric Medical Association (APMA)