Fluid Retention (Edema)

What fluid retention is

Fluid constantly moves out of small blood vessels into the tissues and is drained back by veins and the lymph system. Fluid retention happens when more leaks out than is drained away. The causes fall into a few groups:

• Higher pressure in the veins: from standing still, heart failure, vein valve problems or a blood clot
• Less protein in the blood: albumin holds fluid inside vessels, and levels fall in liver disease, kidney disease that leaks protein and severe malnutrition
• Salt and water retention by the kidneys: in kidney disease, heart failure, and with some medicines and hormones
• Leaky vessels: in inflammation, allergy, burns and infection
• Blocked lymph drainage: lymphedema after cancer surgery or radiation

Signs and symptoms of fluid retention

• Swelling of the feet, ankles and lower legs, often worse in the evening
• Pitting: pressing the swollen skin with a thumb for 5 seconds leaves a dent
• Tight shoes, rings or watch straps, and sock marks on the legs
• Puffy face or eyes, especially on waking
• Stretched, shiny or heavy-feeling skin
• Weight that goes up by several pounds within days
• Stiff, achy joints in swollen areas
• A swollen, tight belly (ascites) in liver disease
• Breathlessness and a cough when fluid collects in the lungs (pulmonary edema)

Common, harmless causes of water retention

• Standing or sitting for long periods, including long flights, as gravity pools fluid in the legs
• Hot weather, which widens blood vessels
• Salty food, because the body holds water to balance the sodium
• The menstrual cycle: hormone changes cause bloating, breast tenderness and puffiness in the week before a period
• Pregnancy: mild swelling of the feet and ankles is very common in the third trimester
• Being less mobile, because calf muscles normally pump fluid up the legs

These causes usually affect both sides, are mild, and improve overnight or with raising the legs.

Fluid retention as a sign of serious underlying conditions

Medicines that cause fluid retention

• Calcium channel blockers for blood pressure, such as amlodipine
• NSAIDs such as ibuprofen and naproxen
• Steroids such as prednisone
• Some diabetes medicines (pioglitazone)
• Estrogen, including some birth control pills and HRT
• Some medicines for nerve pain (gabapentin, pregabalin)

Do not stop a prescribed medicine without asking your doctor. There is often an alternative.

Fluid in one area: wrist, knee or one limb

Fluid that collects in one spot, such as a wrist or knee, is usually local rather than general fluid retention. Common reasons include a ganglion cyst, an injury or sprain, arthritis, gout, infection or tenosynovitis (inflamed tendon sheath). A hot, red, swollen joint needs same-day care to rule out infection.

How doctors find the cause of fluid retention

Your doctor will ask when the swelling started, whether it affects one side or both, whether it pits, and about breathlessness, urine changes, alcohol, pregnancy and medicines. They will check your weight, blood pressure, heart, lungs, abdomen, neck veins and legs.

Common tests:

• Urine test for protein
• Blood tests: kidney and liver function, albumin, blood count, thyroid function, and BNP or NT-proBNP (a marker of heart strain)
• ECG and echocardiogram (heart ultrasound) if heart failure is suspected
• Doppler ultrasound of the leg if a blood clot or vein problem is possible
• Chest X-ray for fluid in or around the lungs

Treatment for fluid retention

Treatment depends on the cause. For mild swelling and alongside medical treatment:

• Raise your legs above heart level for 30 minutes, 3 or 4 times a day, and when sleeping if possible
• Keep moving: walking and calf exercises pump fluid out of the legs. On long journeys, get up or flex your ankles every hour
• Cut salt: aim for less than 2,300 mg sodium a day, and less if you have heart or kidney disease. Most salt comes from processed and restaurant food
• Compression stockings for venous insufficiency, after checking your circulation is good enough
• Look after the skin on swollen legs with moisturizer, as it breaks down and gets infected easily

Medical treatments:

• Diuretics (water pills) remove excess fluid in heart, kidney and liver disease. They are not a fix for mild or cosmetic water retention and can cause dehydration and low potassium if misused.
• Treating the underlying condition: heart failure medicines, controlling blood pressure, thyroid hormone, anticoagulants for a blood clot
• Changing a medicine that is causing swelling

Frequently asked questions

What are the signs and symptoms of fluid retention?

Swollen feet, ankles, legs or hands, skin that stays dented after you press it, tight rings or shoes, puffy eyes, and weight going up by several pounds over a few days. Fluid in the lungs causes breathlessness, and fluid in the belly causes swelling and tightness.

Can fluid retention be a sign of something serious?

Yes. Although most mild swelling is harmless, fluid retention may be a symptom of heart failure, kidney disease, liver cirrhosis, a blood clot or preeclampsia. Swelling that is new, one-sided, or comes with breathlessness, chest pain, rapid weight gain or reduced urine needs medical review.

How do I get rid of water retention quickly?

For mild water retention, raise your legs, walk regularly, cut down on salty and processed foods, and avoid standing still for long periods. Compression socks help leg swelling. Do not take diuretics unless prescribed, and see a doctor if swelling does not settle within a few days.

Why do my ankles swell at the end of the day?

Gravity pulls fluid into the lower legs when you stand or sit for hours, especially in heat. Swelling that is gone by morning is usually harmless. Swelling that persists overnight, is getting worse or comes with breathlessness can point to heart, kidney or vein problems.

Does drinking more water help fluid retention?

Staying normally hydrated does not cause fluid retention and may help your kidneys clear excess salt. Cutting back on water will not reduce swelling. People with advanced heart or kidney failure are sometimes told to limit fluids, and should follow that advice.