Skin Edema: Types of Cutaneous Swelling Explained

How skin edema develops

Blood in the tiny capillaries is under pressure, which pushes a small amount of fluid into the surrounding tissue all the time. Proteins in the blood, mainly albumin, pull fluid back in. The lymphatic vessels collect whatever is left and return it to the bloodstream.

Edema appears when this balance tips:

• Higher pressure in the veins: heart failure, a blood clot, varicose veins, standing for hours.
• Low protein in the blood: kidney disease that leaks protein (nephrotic syndrome), liver cirrhosis, severe malnutrition.
• Leaky vessels: inflammation, burns, allergy, infection.
• Blocked lymph drainage: lymph node removal, radiotherapy, infection or inherited lymphatic problems.

The skin is where edema becomes visible, especially in the lower legs because of gravity, and around the eyes where the skin is loose. For help working out what a swollen area on your body might be, see the skin swelling symptom guide.

Types of skin edema

Pitting edema grading

Doctors sometimes grade pitting by depth or how long the dent lasts, from 1+ (barely visible, rebounds quickly) to 4+ (deep pit lasting more than half a minute). This helps track response to treatment.

Angioedema

Angioedema is swelling of the deeper layers of skin and the lining of the mouth, throat and gut. Allergic angioedema comes with hives and responds to antihistamines and epinephrine. Angioedema from ACE inhibitor blood pressure medicines and hereditary angioedema are caused by a chemical called bradykinin. They do not respond to antihistamines or epinephrine, and need specific treatment.

Lymphedema

Lymphedema starts as soft swelling but gradually becomes firm as fat and scar tissue build up in the skin. It raises the risk of repeated cellulitis. Early treatment keeps it from progressing.

Causes and risk factors

• Heart: heart failure causes swelling of both legs with breathlessness and tiredness.
• Kidneys: nephrotic syndrome causes puffy eyes and legs with foamy urine. Chronic kidney disease causes fluid overload.
• Liver: cirrhosis causes leg swelling and fluid in the abdomen.
• Veins: chronic venous insufficiency causes ankle swelling, brown staining and itchy skin.
• Medicines: calcium channel blockers, steroids, NSAIDs, pioglitazone, estrogen, gabapentin and pregabalin.
• Pregnancy and hormones: mild ankle edema is common late in pregnancy and before periods.
• Thyroid: low thyroid causes puffy, non-pitting facial swelling.

Diagnosis

Diagnosis starts with the pattern: one area or both sides, pitting or not, fast or slow. A doctor will examine the heart, lungs, abdomen and skin, and press over the shins to check for pitting.

Common tests include:

• urine dipstick for protein, and blood tests for kidney and liver function, albumin, thyroid hormones and BNP (a heart strain marker)
• Doppler ultrasound for clots or vein reflux
• echocardiogram if heart failure is suspected
• C4 and C1-inhibitor levels for recurrent angioedema without hives
• lymphoscintigraphy in uncertain lymphedema

Treatment

Treat the cause

Diuretics for heart failure and kidney fluid overload, anticoagulants for blood clots, thyroid hormone for hypothyroidism, antibiotics for cellulitis, and switching a medicine that causes swelling.

Measures that help most types

• Elevation: raise swollen legs above heart level for 30 minutes several times a day.
• Compression: graduated stockings or wraps reduce venous edema and lymphedema. Check with a doctor first if you have poor circulation or diabetes.
• Movement: walking and calf exercises pump fluid back toward the heart.
• Lower salt intake reduces fluid retention.
• Skin care: moisturize daily and treat small cuts promptly, because swollen skin breaks down and gets infected easily.

Specific treatments

• Lymphedema: complete decongestive therapy, which combines manual lymph drainage massage, multilayer bandaging, exercise and skin care, followed by fitted compression garments.
• Allergic angioedema: antihistamines, and epinephrine for throat swelling.
• Hereditary or ACE inhibitor angioedema: stopping the ACE inhibitor, and C1-inhibitor replacement or bradykinin-blocking drugs prescribed by a specialist.

Complications

Untreated skin edema can lead to stretched, fragile skin, leg ulcers, weeping fluid, cellulitis, reduced mobility and, in lymphedema, permanent thickening of the skin.

Frequently asked questions

What is skin edema?

Skin edema is swelling caused by fluid that has leaked out of small blood vessels and collected in the skin and the tissue beneath it. It is most common in the lower legs and around the eyes. It is a sign of an underlying problem rather than a disease by itself.

What is the difference between pitting and non-pitting edema?

Pitting edema leaves a dent for a few seconds after you press it, because the fluid is free to move. It is typical of heart, kidney, liver and vein problems. Non-pitting edema is firm and does not dent, as in lymphedema, thyroid disease and angioedema.

Can drinking more water reduce edema?

Not usually. Drinking enough water is fine and does not cause edema in healthy people, but it does not remove fluid either. Reducing salt, raising your legs, moving more and treating the cause help more. People with heart or kidney failure may be told to limit fluids.

Is skin edema dangerous?

It depends on the cause. Mild swelling from heat or long sitting is harmless. Edema from heart, kidney or liver disease needs treatment, and swelling of the throat or a swollen, painful leg can be an emergency.