Swelling is due to excess fluid in the tissues. The fluid is predominantly water.

Swelling may be widespread or confined to a single limb or part of a limb. Swelling is often in the feet and lower legs. However, people who are required to remain in bed for extended periods (bed rest) sometimes develop swelling in the buttocks, genitals, and back of the thighs. Women who lie on only one side may develop swelling in the breast they lie on. Rarely, a hand or an arm swells.

Sometimes a limb suddenly swells. More often, swelling develops slowly, beginning with weight gain, puffy eyes upon awakening in the morning, and tight shoes at the end of the day. Swelling may develop so gradually that people do not notice until the swelling is considerable. Sometimes people have a feeling of tightness or fullness. Other symptoms may be present depending on the cause of the swelling and may include shortness of breath or pain in the affected limb.

Swelling is sometimes described as pitting. When pressure is applied to the swollen area, an indentation that persists for some time is left after the pressure is released. Any form of pressure (for example, a finger or the elastic in socks) can cause pitting. Edema is described as nonpitting if no indentation is left.

Causes

Swelling that occurs throughout the body has different causes than swelling that is confined to a single limb or part of a limb.

Widespread swelling is most commonly caused by

• Heart failure
• Liver failure
• Kidney disorders (especially nephrotic syndrome)

These disorders all cause fluid retention, which is the cause of the swelling.

Another cause of swelling of the lower legs is pooling of blood in the legs. Many obese, middle-aged or older people normally have a small amount of swelling at the end of the day due to blood pooling. This swelling typically goes away by morning. Blood can also pool in the legs if the valves in the veins are widened or damaged (chronic venous insufficiency) such as may occur in people who previously had blood clots in the legs. In such people, the swelling usually does not go away overnight.

Many women normally have some swelling during the later stages of pregnancy. However, women who have a large amount of swelling, particularly if swelling also involves hands and face and is accompanied by high blood pressure, may have preeclampsia (see Complications of Pregnancy: Preeclampsia), which can be dangerous.

Swelling that is confined to a single limb or part of a limb is most commonly caused by

• A blood clot in a deep-lying vein in a limb (deep vein thrombosis)
• Skin infection (cellulitis)
• Blockage of a lymph vessel

Many disorders increase risk of blood clots in a vein (see Venous Disorders: Causes). Most often, these clots develop in a leg vein but sometimes they occur in an arm vein. Blood clots in a vein can be dangerous if the clot breaks off and travels to the lungs, blocking an artery there (called pulmonary embolism).

Cellulitis typically causes swelling of the skin over only part of a limb. Much less often, an infection deep under the skin or in the muscles can cause the whole limb to swell.

Lymph vessels occur throughout the body help drain fluid from tissues (see Lymphatic Disorders: Overview of the Lymphatic System). If a tumor pushes on the lymph vessels or surgery removes some of the lymph vessels (for example, when women with breast cancer have lymph nodes removed from the armpit), a limb can swell. In many tropical countries, certain parasites can block lymph vessels and cause swelling (lymphatic filariasis).

Sometimes, an allergic reaction causes swelling around the mouth (angioedema). Angioedema can also be a hereditary disorder in which swelling comes and goes at irregular intervals.

Evaluation

Although swelling may seem like a minor irritation, especially if it does not cause discomfort and goes away while a person is sleeping, it can be a symptom of a serious disorder. The following information can help people decide when a doctor's examination is needed and know what to expect during the evaluation.

Warning signs: In people with swelling, certain symptoms and characteristics are cause for concern. They include

• Sudden onset
• Swelling of only one leg
• Significant pain or tenderness
• Shortness of breath
• Coughing up blood

When to see a doctor: People who have warning signs should see a doctor right away. People without warning signs who have a history of heart, lung, or kidney disease or who are pregnant should see a doctor within a few days. Other people without warning signs should schedule a doctor's appointment when convenient. Typically a delay of a week or so is not harmful.

What the doctor does: Doctors first ask questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the swelling and the tests that may need to be done.

Doctors ask about the location and duration of the swelling and presence and degree of pain or discomfort. Women are usually asked whether they are pregnant and whether swelling seems related to menstrual periods. Doctors also ask whether the person has any disorders (for example, heart, liver, or kidney disorders) or takes any drugs (for example, minoxidil, nonsteroidal anti-inflammatory drugs, or amlodipine and other calcium channel blockers) that are known to cause swelling. Doctors also ask about the amount of salt used in cooking and at the table because excess salt can make swelling worse, particularly in people with heart or kidney disorders.

Doctors look for symptoms that may indicate the cause of swelling. For example, people with heart failure may have shortness of breath during exertion or may wake a night with shortness of breath. People with swelling and easy bruising may have a liver disorder, and people who have recently had surgery or a cast on their leg may have deep vein thrombosis.

Doctors may ask people with swelling that is long lasting to keep a record of their daily weight so that increases in swelling are detected quickly.

During the physical examination, doctors pay particular attention to the area of swelling, but they also carefully examine the person for other signs. Doctors listen to the heart and lungs with the stethoscope because swelling may be a sign of a heart disorder.

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Some Causes and Features of Swelling Cause Common Features* Tests† Angioedema (allergic, idiopathic, or hereditary) Painless swelling of the face, lips, and sometimes tongue Sometimes itching or tight sensation Swelling that does not remain indented after being pressed (nonpitting swelling) Only a doctor's examination A blood clot in a deep-lying vein in a leg (typically), an arm, or the pelvis (deep vein thrombosis) Sudden, nonpitting swelling Usually pain, redness, warmth, and/or tenderness in the affected area If the clot travels to and blocks an artery to the lung (pulmonary embolism), usually shortness of breath and sometimes coughing up blood Sometimes in people who have risk factors for blood clots, such as recent surgery, an injury, bed rest, a cast on a leg, hormone therapy, or cancer Ultrasonography Chronic venous insufficiency (causing blood to pool in the legs) Swelling in one or both ankles or legs Chronic mild discomfort, aching, or cramps in the or legs but no pain Sometimes reddish brown, leathery areas on the skin and shallow sores on the lower legs Often varicose veins Only a doctor's examination Drugs (such as minoxidil, nonsteroidal anti-inflammatory drugs, estrogens, fludrocortisone, and some calcium channel blockers) Painless swelling that remains slightly indented after being pressed (slight pitting) in both legs and feet Only a doctor's examination Heart failure Painless swelling that remains indented after being pressed (pitting) in both legs and feet Often shortness of breath during exertion or while lying down and during sleep Often in people known to have heart disease and/or high blood pressure Chest x-ray ECG Usually echocardiography Infection of the skin (cellulitis) An irregular area of redness, warmth, and tenderness on part of one limb Nonpitting swelling Sometimes fever Only a doctor's examination Infection deep under the skin or in the muscles (rare) Deep, constant pain in one limb Redness, warmth, tenderness, and nonpitting swelling that feels tight Signs of severe illness (such as fever, confusion, and a rapid heart rate) Sometimes a foul discharge, blisters, or areas of blackened, dead skin Blood and tissue cultures X-rays Sometimes MRI Kidney disease (mainly nephrotic syndrome) Widespread, painless, pitting swelling Often fluid within the abdomen (ascites) Sometimes puffiness around the eyes or frothy urine Measurement of protein in a urine specimen Liver disease if chronic Widespread, painless, pitting swelling Often fluid within the abdomen (ascites) Causes that are often apparent based on history (such as alcohol abuse or hepatitis) Sometimes small spiderlike blood vessels that are visible in the skin (spider angiomas), reddening of the palms and, in men, breast enlargement and a decrease in the size of the testes Measurement of albumin in the blood Other blood tests to evaluate liver function Lymphatic vessel obstruction due to surgery or radiation therapy for cancer Painless, nonpitting swelling of one limb A cause (surgery or radiation therapy) that is apparent based on history Only a doctor's examination Lymphatic filariasis (a lymph vessel infection due to certain parasitic worms) Painless, nonpitting swelling of one limb and sometimes the genitals In people who have been in a developing country where filariasis is common Examination of a blood sample under a microscope Normal swelling A small amount of pitting swelling of both feet and/or ankles that occurs at the end of the day and resolves by morning No pain, redness, or other symptoms Only a doctor's examination Pregnancy or a normal premenstrual symptom Painless, pitting swelling in both legs and feet Usually relieved to some extent by rest and leg elevation In women known to be pregnant or about to have a menstrual period Only a doctor's examination Pregnancy, with preeclampsia Painless, pitting swelling in both legs and feet High blood pressure (often new) Occurring during the 3rd trimester of pregnancy Measurement of protein in urine Pressure on a vein (for example, by a tumor, pregnancy, or extreme abdominal obesity) Painless swelling that develops slowly Ultrasonography or CT if a tumor is suspected *Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. †In most people with swelling, doctors do a complete blood count, other blood tests, and urinalysis (to check for protein in the urine). CT = computed tomography; ECG = electrocardiography; MRI = magnetic resonance imaging. Some Causes and Features of Swelling Cause Common Features* Tests† Angioedema (allergic, idiopathic, or hereditary) Painless swelling of the face, lips, and sometimes tongue Sometimes itching or tight sensation Swelling that does not remain indented after being pressed (nonpitting swelling) Only a doctor's examination A blood clot in a deep-lying vein in a leg (typically), an arm, or the pelvis (deep vein thrombosis) Sudden, nonpitting swelling Usually pain, redness, warmth, and/or tenderness in the affected area If the clot travels to and blocks an artery to the lung (pulmonary embolism), usually shortness of breath and sometimes coughing up blood Sometimes in people who have risk factors for blood clots, such as recent surgery, an injury, bed rest, a cast on a leg, hormone therapy, or cancer Ultrasonography Chronic venous insufficiency (causing blood to pool in the legs) Swelling in one or both ankles or legs Chronic mild discomfort, aching, or cramps in the or legs but no pain Sometimes reddish brown, leathery areas on the skin and shallow sores on the lower legs Often varicose veins Only a doctor's examination Drugs (such as minoxidil, nonsteroidal anti-inflammatory drugs, estrogens, fludrocortisone, and some calcium channel blockers) Painless swelling that remains slightly indented after being pressed (slight pitting) in both legs and feet Only a doctor's examination Heart failure Painless swelling that remains indented after being pressed (pitting) in both legs and feet Often shortness of breath during exertion or while lying down and during sleep Often in people known to have heart disease and/or high blood pressure Chest x-ray ECG Usually echocardiography Infection of the skin (cellulitis) An irregular area of redness, warmth, and tenderness on part of one limb Nonpitting swelling Sometimes fever Only a doctor's examination Infection deep under the skin or in the muscles (rare) Deep, constant pain in one limb Redness, warmth, tenderness, and nonpitting swelling that feels tight Signs of severe illness (such as fever, confusion, and a rapid heart rate) Sometimes a foul discharge, blisters, or areas of blackened, dead skin Blood and tissue cultures X-rays Sometimes MRI Kidney disease (mainly nephrotic syndrome) Widespread, painless, pitting swelling Often fluid within the abdomen (ascites) Sometimes puffiness around the eyes or frothy urine Measurement of protein in a urine specimen Liver disease if chronic Widespread, painless, pitting swelling Often fluid within the abdomen (ascites) Causes that are often apparent based on history (such as alcohol abuse or hepatitis) Sometimes small spiderlike blood vessels that are visible in the skin (spider angiomas), reddening of the palms and, in men, breast enlargement and a decrease in the size of the testes Measurement of albumin in the blood Other blood tests to evaluate liver function Lymphatic vessel obstruction due to surgery or radiation therapy for cancer Painless, nonpitting swelling of one limb A cause (surgery or radiation therapy) that is apparent based on history Only a doctor's examination Lymphatic filariasis (a lymph vessel infection due to certain parasitic worms) Painless, nonpitting swelling of one limb and sometimes the genitals In people who have been in a developing country where filariasis is common Examination of a blood sample under a microscope Normal swelling A small amount of pitting swelling of both feet and/or ankles that occurs at the end of the day and resolves by morning No pain, redness, or other symptoms Only a doctor's examination Pregnancy or a normal premenstrual symptom Painless, pitting swelling in both legs and feet Usually relieved to some extent by rest and leg elevation In women known to be pregnant or about to have a menstrual period Only a doctor's examination Pregnancy, with preeclampsia Painless, pitting swelling in both legs and feet High blood pressure (often new) Occurring during the 3rd trimester of pregnancy Measurement of protein in urine Pressure on a vein (for example, by a tumor, pregnancy, or extreme abdominal obesity) Painless swelling that develops slowly Ultrasonography or CT if a tumor is suspected *Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. †In most people with swelling, doctors do a complete blood count, other blood tests, and urinalysis (to check for protein in the urine). CT = computed tomography; ECG = electrocardiography; MRI = magnetic resonance imaging.

Testing: For most people with widespread swelling, blood tests are done to evaluate the function of the heart, kidneys, and liver. Urinalysis is usually also done to check for large amounts of protein, which can indicate nephrotic syndrome, or in pregnant women, preeclampsia. Other tests are done based on the suspected cause. For example, in people with isolated leg swelling, doctors may do ultrasonography to look for blockage of a vein in the leg.

Treatment

Specific causes are treated (for example, anticoagulants [blood thinners] are given to people with blood clots in the legs). Any drugs that caused the swelling are stopped or changed if possible.

Because swelling itself is not harmful, doctors do not give water pills (diuretics) to people unless they are needed to treat the cause of the swelling (such as heart failure). However, some simple general measures, such as sitting with the legs elevated or limiting the amount of salt in the diet, sometimes help relieve swelling.

Key Points

• Swelling may be widespread or confined to a single area.
• Not all swelling is harmful.
• The main causes of widespread swelling are heart, liver, and kidney disorders.
• The main causes of swelling of a single limb are blood clots in a vein and an infection.
• Sudden onset of swelling may indicate a serious disorder, so people should see a doctor right away.

Last full review/revision October 2012 by Lyall A. J. Higginson, MD