Pulmonary embolism, a blood clot in your lungs, isn't the only serious complication that can result from a blood clot deep in your veins. Although many people with deep vein thrombosis (DVT) recover completely, some go on to experience symptoms in their arms or legs for years after their initial diagnosis.

Known collectively as post-thrombotic syndrome or post-phlebitic syndrome, the symptoms can be painful and debilitating.

Post-Thrombotic Syndrome Symptoms

In a healthy person, small valves inside the veins ensure that blood flows in the right direction toward the heart.

“But when the veins are damaged from the blood clots, it may result in unwanted blood flow away from the heart while standing or walking,” says Scott Sundick, MD, the chief of vascular surgery at Overlook Medical Center in Summit, New Jersey. This allows fluid to pool in the arms and legs, which can lead to a number of unpleasant symptoms.

Post-thrombotic syndrome symptoms include:

Pain or aching
Leg or arm swelling
Heaviness
Cramping
Redness
Skin discoloration or dark pigmentation
Bluish fingers or toes
Dry skin or eczema
Varicose veins

Approximately one-third to one-half of people with DVT will go on to have post-thrombotic syndrome, according to the Centers for Disease Control and Prevention (CDC).

Post-Thrombotic Syndrome Complications

If a vein is completely blocked, smaller veins nearby may enlarge to move blood past the blockage. If these smaller veins get large enough to serve this way, symptoms are usually mild. But for some people, the smaller veins do not get big enough to help blood bypass a blockage and drain all the blood that has pooled in the arms or legs. Then, symptoms worsen.

Severe post-thrombotic syndrome can lead to sores or ulcers, which can be chronic and tough to treat. According to research published in June 2022 in the Journal of Vascular Surgery Cases, Innovations, and Techniques, up to 5 percent of people with the condition will develop ulcers.

Post-thrombotic syndrome is a lifelong condition. Symptoms may come and go over time. They also may not develop right away.

According to the National Blood Clot Alliance, symptoms typically appear six months after DVT diagnosis but may occur up to two years after the blood clot. After two years, it’s unlikely post-thrombotic syndrome will develop.

Easing Pain and Other Symptoms

When it comes to reducing complications associated with DVT, including post-thrombotic syndrome, prevention is key.

“Those most at risk for post-phlebitic syndrome are patients with recurrent or extensive deep vein thrombosis,” Dr. Sundick says.

These individuals will need to take more precautions, which may include going on anticoagulants, or blood thinners, sometimes for life.

Aside from medication, if you experience swelling after DVT, it's important to wear fitted compression stockings to improve blood flow throughout the day while you're sitting or standing. This can reduce the incidence of post-thrombotic syndrome, says Christopher J. Agrusa, MD, a vascular surgeon at NewYork-Presbyterian and Weill Cornell Medicine in New York City.

While the data regarding how long to use compression stockings is not clear, “most physicians recommend the use of compression stockings immediately after the diagnosis of a DVT and continuing compression therapy based on the signs and symptoms of post-thrombotic syndrome,” Dr. Agrusa says.

Various types of compression stockings exist, including above-the-knee stockings for swelling in the thigh, and sleeves (known as gauntlets), for arm swelling or pain. Your doctor can tell you what would be best for you.

If compression stockings are not effective, your doctor may recommend that you use a device called a compression pump to improve blood flow.

According to Agrusa, other ways to ease symptoms of post-thrombotic syndrome include:

Elevating your arm or leg above your heart while lying down or sleeping
Losing excess weight
Exercising to strengthen the muscles in your arms and legs

Certain over-the-counter and prescription medications can also help ease pain associated with post-thrombotic syndrome. But, if you're taking a blood-thinning medication, you should not take drugs that contain aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, because NSAIDs increase bleeding risk. Pain-relieving medications that could be considered include acetaminophen, tramadol, and oxycodone.

Finally, remember that if you notice something’s off, it’s important to talk to your doctor. “The best way to avoid post-phlebitic syndrome is to seek immediate consultation if you develop severe leg swelling,” Sundick says. If an extensive deep vein thrombosis is diagnosed, your doctor can perform a procedure to rapidly remove the blood clots.

“This may prevent damage to the valves and thus prevent the occurrence of post phlebitic syndrome,” Sundick says.

Additional reporting by Ashley Welch.