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Sock marks on your legs are very common. Most socks contain elastic to keep them from slipping down. Pressure from the elastic leaves a mark.
The marks may be more noticeable if the soft tissue in your legs is swollen with fluid. This is called peripheral edema.
Most of the time, peripheral edema develops because you’re retaining fluid. Often the swelling is mild, goes away on its own, and isn’t associated with other symptoms.
Sometimes peripheral edema is more severe, however. This may indicate it’s caused by an underlying medical condition. When it is, there are usually other symptoms, and the edema doesn’t improve without treatment.
When peripheral edema is more serious
When other symptoms occur with peripheral edema, you might have a serious medical condition that requires urgent medical attention. Worrisome symptoms and their possible causes include:
- chest pain: heart failure
- dizziness or fainting: heart failure
- shortness of breath, especially when lying flat: heart failure
- swelling in only one leg: deep venous thrombosis (DVT), caused by a blood clot in a vein, or cellulitis
- sudden onset of painful swelling in your calf: DVT
- little urine production: kidney disease
- abdominal swelling: liver disease
- abdominal pain: tumor
- sudden high blood pressure during pregnancy: preeclampsia
Peripheral edema that’s moderate to severe, getting worse, or doesn’t improve with rest is more serious. It should be evaluated by your doctor, especially if you have other symptoms or a history of heart, liver, or kidney disease.
Peripheral edema is divided into two types based on what happens when you press on the swollen area:
- pitting edema, in which a dimple or “pit” persists when you stop pressing
- nonpitting edema, in which the dimple immediately disappears when you stop pressing
Sock marks are more likely if you have pitting edema.
Other symptoms of peripheral edema include:
- tight, shiny skin
- fluid oozing from the skin (if severe)
Most often, peripheral edema is the result of fluid retention rather than an underlying condition. The swelling is usually mild and temporary.
When you stand or sit for long periods throughout the day, gravity pulls blood into your legs. The increased pressure pushes fluid from the blood vessel into the soft tissue, causing mild swelling.
Swelling related to gravity is called dependent edema. It’s more pronounced at the end of the day, which is why sock marks are typically worse in the evening. They are usually gone by morning.
Eating lots of salt makes your body retain water. This leads to peripheral edema, which may cause more noticeable sock marks the next evening.
Hormone levels change throughout a woman’s menstrual cycle. This can cause water retention and leg swelling the week before menstruation.
As it enlarges, a pregnant woman’s uterus can push on the blood vessels leading to her legs. This slows the movement of blood from her legs up to her heart, which can lead to peripheral edema.
Most pregnant women get peripheral edema, but it can also be a sign of a serious condition called preeclampsia. Other symptoms are the sudden onset of high blood pressure and protein in your urine (proteinuria). It requires urgent medical attention.
Peripheral edema often occurs in hot weather. Heat causes your blood vessels to open wider, so more blood pools in your legs. If fluid leaks into the tissue, edema develops.
Being obese can cause excess fat in your abdomen and pelvis to push on blood vessels, slowing blood flow out of your legs. It accumulates in your leg veins, and the increased pressure pushes fluid into the soft tissue.
Peripheral edema caused by an underlying medical condition is generally more severe and doesn’t go away without treatment.
One-way valves in your veins keep blood from backing up into your legs instead of moving toward your heart.
These valves can get weak and start to fail with age. Blood then backs up in your leg veins and leads to peripheral edema. This condition is called venous insufficiency. It can make your legs cramp or ache.
Congestive heart failure
Other symptoms include rapid weight gain and shortness of breath.
Some medications can cause peripheral edema, including drugs for:
- contraception: estrogen-containing birth control pills
- diabetes: rosiglitazone (Avandia), pioglitazone (Actos)
- high blood pressure: calcium channel blockers, such as amlodipine (Norvasc) and nifedipine (Adalat CC, Afeditab CR, and Procardia XL)
- inflammation: nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil)
- Parkinson’s disease: pramipexole (Mirapex)
- seizures: gabapentin (Neurontin)
Peripheral edema in only one leg is never normal and requires urgent medical attention. Causes include:
A blood clot in your leg vein is called a deep vein thrombosis, or DVT. It causes sudden pain and swelling, usually in your calf.
Without prompt treatment, the clot can break off and travel to your lungs. This is called a pulmonary embolism and can be life-threatening.
Infected skin or soft tissue (cellulitis) is usually swollen. It may also be red, warm, and tender. Prompt treatment is necessary to prevent the infection from spreading to your bloodstream or bone.
Lymph, fluid containing white blood cells, flows through your lymph nodes and special channels throughout your body.
Lymphedema develops when a tumor or other mass pushes on and blocks lymph channels, or when lymph nodes are surgically removed or damaged by radiation therapy. Your leg swells when the nodes or channels in your pelvis are involved.
Your health history and a physical exam will give your doctor clues about the cause of your leg swelling, but tests are often needed for the diagnosis.
The test is chosen based on the organ being evaluated.
- blood tests, which evaluate the function of most organs, including your heart, liver and kidneys, and albumin level
- urinalysis, which assesses kidney function
- chest X-ray, an imaging test that assesses your lungs and heart
- electrocardiogram, another test to evaluate your heart’s function
- echocardiogram, an imaging test that helps your doctor assess your heart
- ultrasound, an imaging test to help diagnose DVT and abdominal mass (ascites)
- abdominal CT, an imaging test that helps your doctor check for an abdominal mass
There are general things you can do to help reduce mild peripheral edema. You can also try these alongside specific treatment for the medical condition causing your edema.
Ways to reduce the swelling
- Reduce your salt intake.
- Lose weight.
- Elevate your feet above the level of your heart while sitting or lying down so that gravity pushes the fluid out of your legs instead of into them.
- Take frequent breaks and elevate your legs whenever possible if you’re standing or sitting for a long time.
- Wear compression stockings to apply pressure that keeps fluid out of your legs. Shop for nonprescription compression stockings online.
- Exercise your calf muscles. Contractions help push blood through your veins so it can’t pool in your leg and move into the soft tissue.
Diuretics (water pills) remove excess fluid from your body. They’re only used when peripheral edema is caused by an underlying condition.
Treatments for specific underlying causes
Treatments may depend on what’s causing peripheral edema. Here are some of the possible treatment options for specific causes of peripheral edema:
- venous insufficiency: compression stockings, removing the vein (vein stripping), or surgical repair
- congestive heart failure: diuretics or medications that help your heart work more efficiently
- kidney disease: medications that increase urine production, dialysis, or a kidney transplant
- liver disease: antiviral medication for hepatitis, limiting alcohol, or a liver transplant
- malnutrition: a nutritious diet that contains an adequate amount of protein
- lymphedema: compression stockings or lymphatic drainage massage
- DVT: blood-thinning medication
- cellulitis: antibiotics
Sock marks themselves aren’t harmful, but very noticeable ones could mean you have peripheral edema.
The outlook of peripheral edema depends on the cause. Temporary edema that’s mild and doesn’t occur with other symptoms shouldn’t be worrisome.
Peripheral edema that’s more severe and persistent may be due to a serious medical condition. The outlook depends on the cause, but it improves with prompt diagnosis and treatment.
Sock marks are caused by pressure from the elastic in them. Peripheral edema can make sock marks more noticeable.
Most often, peripheral edema develops when excess fluid in your body is pulled into your legs by gravity. The edema is usually mild, temporary, and harmless.
However, peripheral edema can be a symptom of an underlying medical condition. If so, the edema is more severe and persistent, and there are usually other symptoms.
If your sock marks are more noticeable, look at your legs. If there’s new or increased swelling or pitting edema, see your doctor right away. You may have a medical condition that requires prompt treatment.