Edema (Fluid Swelling): Types and Causes

How edema forms

Blood vessels constantly leak a small amount of fluid into the tissues, and the lymphatic system drains it back. Edema develops when this balance tips:

• Higher pressure in veins, from heart failure, blood clots or failing vein valves, pushes more fluid out
• Low blood protein (albumin), from kidney, liver or nutritional problems, means less fluid is pulled back into the blood
• Leaky capillaries, from inflammation, infection, burns or allergy
• Blocked lymph drainage, from surgery, radiation, cancer or infection
• Salt and water retention, from kidney problems, hormones or medicines

Types of edema

Doctors grade pitting edema from 1+ (a slight 2 mm dent that disappears quickly) to 4+ (a deep dent of 8 mm or more that lasts over 2 minutes).

Common causes of edema

Everyday causes

• Standing or sitting still for long periods, including long flights
• Hot weather
• A salty meal
• Premenstrual fluid retention
• Pregnancy, especially the third trimester
• Being overweight

Medicines

• Calcium channel blockers (especially amlodipine)
• NSAIDs such as ibuprofen and naproxen
• Steroids and hormones, including estrogen
• Some diabetes medicines (pioglitazone)
• Gabapentin and pregabalin

Medical conditions

• Heart failure: swelling of both ankles and legs, breathlessness, tiredness, waking at night breathless
• Kidney disease and nephrotic syndrome: puffiness around the eyes in the morning, foamy urine, swelling everywhere
• Cirrhosis: fluid in the belly (ascites) and legs, yellow skin
• Chronic venous insufficiency: swollen ankles worse at the end of the day, varicose veins, brownish skin
• Deep vein thrombosis: one swollen, painful, warm calf or leg
• Lymphedema: firm swelling after lymph node removal, radiation or infection
• Underactive thyroid: puffy face and non-pitting swelling of the shins
• Malnutrition: low protein

Edema in the shoulder, wrist and other joints

Swelling in a single joint is usually local, not from heart or kidney problems.

• Shoulder edema: often from rotator cuff injury, bursitis, a dislocation or fracture, arthritis or infection. Swelling around the collarbone and shoulder on one side that worsens through the day can come from a blocked vein in the upper chest or arm (upper limb DVT or thoracic outlet syndrome) and needs prompt assessment.
• Wrist edema: from sprains, fractures, tendon inflammation (tenosynovitis), gout, rheumatoid arthritis or infection. In older adults, a hot, red, swollen wrist is often gout or pseudogout. Swelling spreading from the wrist up the arm in someone with lymphedema needs a doctor to rule out cellulitis.
• Hand edema: from tight rings, heat, pregnancy, arthritis or allergy.

Bone and muscle edema on MRI

Some people first hear the word "edema" on an MRI report.

• Bone marrow edema: extra fluid inside a bone, seen on MRI. It shows the bone is stressed or injured: a bone bruise, a stress fracture, arthritis, avascular necrosis or, rarely, infection or tumor. Bone edema in the shoulder or knee after an injury usually settles over weeks to months with rest and gradual return to activity.
• Muscle edema: fluid within a muscle on MRI. It can follow a strain, intense exercise, nerve damage, or inflammation of the muscle (myositis). It may affect a single muscle or several muscle groups, as in rhabdomyolysis, where muscle breaks down widely after extreme exercise, crush injuries, heat or certain drugs, and releases proteins that can damage the kidneys.

Throat and vocal cord edema

• Throat swelling after an injury, such as a blow to the neck or swallowing something hot or caustic, can worsen over hours and block the airway. Increasing hoarseness, noisy breathing or trouble swallowing needs emergency care. Swelling that does not settle over days needs an ENT examination.
• Reinke's edema is a jelly-like swelling of the vocal cords that causes a deep, husky voice. Smoking is the main cause, with voice overuse and acid reflux contributing. Stopping smoking is essential, and surgery can help.

How doctors find the cause

A doctor will ask when the swelling started, whether it is one-sided or both-sided, about breathlessness, medicines, urine changes and recent travel or surgery. They will press on the swelling, listen to your heart and lungs, and check your belly and neck veins.

Tests may include:

• urine test for protein
• blood tests: kidney and liver function, albumin, thyroid, and BNP (a heart failure marker)
• D-dimer and leg ultrasound if a clot is possible
• chest X-ray and echocardiogram
• MRI or X-ray for joint swelling

Treatment

Treatment targets the cause. General measures that help:

• Raise the swollen limb above heart level for 30 minutes several times a day.
• Move: walking and ankle pumps help the calf muscles pump fluid back.
• Compression stockings for venous swelling, once a doctor has checked circulation is adequate.
• Cut down salt.
• Skin care: keep swollen skin clean and moisturized to prevent cracks and infection.
• Diuretics (water pills): for heart, kidney or liver causes, prescribed by a doctor. They are not a fix for swelling from veins or standing.
• Review medicines that may be causing it. Do not stop a prescribed medicine without advice.

Frequently asked questions

What is edema?

Edema is swelling caused by fluid trapped in the body's tissues. It most often affects the feet, ankles and legs but can occur anywhere, including the lungs and brain. It has many causes, from standing too long to heart, kidney and liver disease.

What is the most common cause of edema?

Swelling of the feet and ankles from standing or sitting for long periods, heat and vein problems is the most common. Among medical causes, heart failure, chronic venous insufficiency, kidney disease and medicines such as amlodipine are frequent.

Why do I have edema in my shoulder?

Shoulder swelling usually comes from a local problem: a rotator cuff or labrum injury, bursitis, arthritis, a fracture or infection. Swelling of the whole arm and shoulder on one side may mean a blocked vein. An MRI may also show bone or soft tissue edema after injury.

What is muscle edema?

Muscle edema is extra fluid within a muscle, usually seen on MRI. It can come from strains, hard exercise, nerve injury, inflammation of the muscle, or rhabdomyolysis. The cause determines the treatment, from rest and physical therapy to urgent hospital care.

Can an elderly man get edema in his wrist?

Yes. In older adults, wrist swelling often comes from arthritis, gout or pseudogout, a fall injury, or swelling from heart failure or medicines. A hot, red, very painful wrist needs prompt assessment to rule out gout or infection.

When is edema an emergency?

Edema is an emergency when it affects the face, lips or throat, or comes with shortness of breath, chest pain, coughing blood, or confusion. Sudden swelling of one leg also needs same-day assessment for a blood clot.