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Sever’s Disease: Heel Pain in Growing Kids and Young Athletes
Your child comes off the field limping, holding the back of one heel. Yesterday’s practice was fine. Today, every step hurts. For many parents,
Medically Reviewed by
Dr. Paul Hanna, DO, RPVI
Board Certified Vascular Surgeon
If you have been told you have a blood clot in your leg, or you have a swollen calf that worries you, one question tends to come up fast. How quickly could that clot reach the lungs? It is a fair thing to ask, and the honest answer may feel unsatisfying. Nobody can predict it for a particular person.
What we can do is explain how a leg clot becomes a lung clot, which warning signs matter, and what to do right away. If you have chest pain, trouble breathing, or you are coughing up blood, stop reading and call 911.
There is no reliable timeline. A clot that forms in a deep leg vein can stay in place for days, and it may never move. Another can break loose without warning. Once a piece breaks away, it is carried by the bloodstream, and the trip itself is not something doctors can measure or forecast in advance.
That is why we avoid giving numbers. A promise like “hours” or “days” would not be accurate, and it could keep someone from seeking care. The safer rule is simple. If you suspect a clot, treat it as urgent and get evaluated instead of waiting to see what happens.
The Centers for Disease Control and Prevention explains that deep vein thrombosis, or DVT, happens when a blood clot develops in a deep vein, most commonly in the lower leg, thigh, or pelvis. A pulmonary embolism, or PE, occurs when part of that clot breaks off and travels to the lungs.
Think of the clot as a plug that has come loose from where it formed. It moves with the blood through larger and larger veins, passes through the heart, and then gets stuck in a narrower artery in the lung. There, it can block blood flow and strain the heart.
Several things are unknown at the moment a clot forms. How large is it? How firmly is it attached to the vein wall? Is the vein moving a lot, as when a person walks? Is the clot still growing? Each factor changes the odds that a piece will break off, and none of them can be seen from the outside.
Doctors can estimate risk using your history, symptoms, and tests, but they cannot say when, or whether, a particular clot will move. Because of that uncertainty, treatment for a DVT is aimed at preventing problems early, not at guessing a deadline.
The National Heart, Lung, and Blood Institute notes that a pulmonary embolism may cause no symptoms at all. Other times symptoms come on within seconds to minutes. In some people they build more slowly over days to weeks, starting mild and becoming more serious as time passes.
This matters because a mild breathing change should not be brushed off, especially if you have a swollen or painful leg. Some people feel a little short of breath on stairs and assume they are out of shape. Do not assume. Mention it to a doctor.
Mayo Clinic describes three common symptoms of a pulmonary embolism. The first is shortness of breath, which usually appears suddenly and happens even at rest. The second is chest pain, often sharp and felt when you breathe in deeply. The third is fainting, which can happen if heart rate or blood pressure drops suddenly.
It adds that other symptoms can include a cough that brings up blood or blood-streaked mucus, a rapid or irregular heartbeat, lightheadedness, heavy sweating, fever, and clammy or discolored skin. Symptoms vary based on how much of the lung is affected and the size of the clots.
Call 911 right away if you have chest pain, trouble breathing that came on suddenly, fainting or near fainting, or you are coughing up blood. Do not drive yourself, and do not wait for the symptoms to pass. These can be signs of a pulmonary embolism, which is a medical emergency.
If someone near you collapses or cannot catch their breath, call for emergency help and stay with them. Tell the dispatcher about any recent surgery, long travel, or known clot. This is not a situation for an online appointment request or a message to our office.
As noted earlier, a person can have a pulmonary embolism without any symptoms of DVT. That can feel confusing, because the leg looks normal. The clot may have been small or silent, or it may have already left the leg.
It also means a normal-looking leg does not rule out a clot problem if you have breathing symptoms. Doctors look at the whole picture, including your risk factors, your medical history, and any recent triggers such as surgery or a long period of bed rest.
Cleveland Clinic says the symptoms of a clot waiting to dislodge and travel to the lungs may include leg pain, swelling, and warmth, and that these signs should be taken just as seriously. For a full description of what to look for, read our guide to DVT symptoms in the leg.
The same clinic lists many risk factors that make blood more likely to clot. Examples include major surgery, a hospital stay, long periods of sitting, pregnancy, hormone-based medicines, cancer, and clotting disorders. Having a risk factor does not mean you will get a clot, but it is a reason to stay alert.
When your legs stay still for hours, blood moves more slowly through the leg veins. That can raise the chance that a clot forms, especially if you have other risk factors. It applies to long flights and car rides, and also to long days at a desk.
Simple habits can help. Stand and walk when you can, flex your ankles while seated, and drink water on long trips. If you have a history of clots, talk with your doctor before a long flight, since some people need a personal plan.
A leg that is suddenly larger than the other, especially with pain or warmth, is a reason to get checked. It does not always mean a clot, since injuries and other vein or lymph problems can cause swelling too.
Still, one-sided swelling is a pattern we want evaluated quickly. Our post on why one leg may be bigger than the other explains what a vascular surgeon looks for. If you also have trouble breathing or chest pain, call 911 first.
In an emergency room, doctors look at your symptoms, risk factors, and exam, then choose tests. These commonly include blood tests, a check of your oxygen level, and imaging of the lungs, such as a CT scan that uses contrast dye to show blockages.
The exact tests depend on your situation. Some people are tested for clotting in the legs with ultrasound at the same time. The goal is to confirm or rule out a clot quickly, so treatment can start without delay if one is found.
For a suspected DVT, a duplex ultrasound is often the first step. It uses sound waves to show blood flow in the veins and can show whether a vein is blocked. It does not involve radiation, and it is typically done in a short visit.
Our guide to vascular imaging with ultrasound, CTA, and MRA explains how each test works and when each one is used. We also explain how DVT is evaluated and managed on our deep vein thrombosis page.
World Thrombosis Day, a global awareness campaign, says early treatment of deep vein thrombosis can help prevent clots from traveling to the lungs and causing a potentially life-threatening pulmonary embolism. That one idea explains why we encourage prompt evaluation of leg swelling.
Waiting does not make a clot safer. If a clot is found early, a doctor can start treatment while the problem is still in the leg. Early care also gives your team time to look for the cause and plan follow-up in a calmer way.
Blood thinners, also called anticoagulants, are the usual first treatment for a clot. They help keep the clot from growing and lower the chance of new clots. Some people take them by mouth, while others need injections or hospital care at first.
In more serious situations, doctors may use clot-dissolving medicine or a procedure to remove a clot. The right plan depends on the size and location of the clot and your overall health, so it is decided case by case after an exam and testing.
An inferior vena cava filter, or IVC filter, is a small device placed in the large vein that carries blood from the legs to the heart. It is designed to catch clots before they reach the lungs, and it is generally considered for people who cannot take blood thinners.
It is not meant for everyone, and it is often intended as a temporary device. Your doctor weighs the benefits against the risks of leaving any device in place. Our detailed guide to IVC filters explains who may need one, how it works, and when removal is discussed.
Leg swelling has many causes. Injuries, standing for long hours, heart or kidney problems, vein valve trouble, and some medicines can all make the ankles and calves puffy. A clot is only one possibility, and it is the one that needs the fastest answer.
That is why a quick exam matters. Our post on common causes of swollen ankles lists many of the other reasons. Our guide to arterial vs. venous disease explains how vein and artery problems differ.
As mentioned earlier, pregnancy and some hormone-based medicines can raise the chance of clotting. That does not mean they are unsafe for everyone. It means your doctor should know about them whenever a new swollen, painful, or warm leg appears.
If you are pregnant and notice one leg swelling more than the other, do not wait for your next routine visit. Our post on varicose veins during pregnancy explains which leg changes are common and which ones call for a prompt check.
Treatment does not end when the first emergency passes. Follow-up visits let your team check that the plan is working, adjust medicines when needed, and look for ongoing leg symptoms. Take your medicines exactly as prescribed, and ask before stopping any of them.
Tell your doctor about new swelling, pain, or breathing changes between visits. Many people also have questions about travel, exercise, and daily activity after a clot. Bring those questions. A good plan covers prevention of repeat clots as well as the first episode.
One myth says a clot always hurts. In fact, some DVTs cause little or no pain, so waiting for pain before acting can be a mistake. Another says only older adults get clots, when younger people can too, especially with surgery, injury, travel, or hormone-related risk factors.
A third myth says you should massage a sore, swollen calf. Please do not rub or squeeze a leg you think has a clot. Rest it, avoid pressing on it, and get medical care. A fourth myth says the danger passes once the swelling goes down, which is not a safe assumption.
Come ready with a few facts. When did the leg symptoms start? Is one leg affected, or both? Have you had recent surgery, a long trip, a hospital stay, an injury, or a period of bed rest? Are you pregnant or on hormone medicine?
Share any history of clots in you or your close relatives, and list the medicines you take. Mention breathing changes, even small ones. If you have a diagnosed clot, ask what symptoms should send you straight to emergency care.
If you have leg swelling, pain, or a known clot and want a specialist’s opinion, our vascular surgery team in Miami can evaluate your veins and help you plan next steps. You can learn more about Dr. Paul Hanna, our vascular surgeon.
Call us at 833-735-3668 or reach out through our contact page. If you have chest pain, sudden trouble breathing, or you are coughing up blood, call 911 instead. This article is for general education only and does not replace advice from your own doctor.
There is no reliable answer. A clot may stay in the leg for a long time, or a piece may break loose without warning. Because travel time cannot be predicted, any suspected clot should be evaluated promptly.
Common symptoms include sudden shortness of breath, sharp chest pain that is worse when breathing in, and fainting. Some people also cough up blood, feel their heart racing, or sweat heavily. Symptoms can come on quickly or build slowly.
Call 911 if you have chest pain, sudden trouble breathing, fainting, or you are coughing up blood. Do not drive yourself. These can be signs of a pulmonary embolism, which is a medical emergency.
Yes. A person can have a pulmonary embolism without noticing any DVT symptoms in the leg. If you have breathing symptoms, get evaluated even if your legs feel normal.
No. Many clots stay where they formed. But because a piece can break away and there is no way to know ahead of time, doctors treat a diagnosed DVT seriously and monitor it closely.
It depends. Some people are encouraged to stay active once treatment has started, while others are told to rest at first. Follow your doctor’s instructions, and never massage or squeeze a leg you think has a clot.
Not always, but risk can often be lowered. Keeping the blood moving on long trips, following your doctor’s advice around surgery or hospital stays, and treating a leg clot early all help. Ask your doctor about your own risk.
Centers for Disease Control and Prevention: About Venous Thromboembolism (Blood Clots)
National Heart, Lung, and Blood Institute: Pulmonary Embolism (PE)
Mayo Clinic: Pulmonary Embolism, Symptoms and Causes
Dr. Paul Hanna is a board-certified vascular surgeon with specialized fellowship training in complex vascular interventions and minimally invasive endovascular techniques. He serves as Director of Vascular Surgery and General Surgery at South Florida Multispecialty Medical Group, with over a decade of experience treating vascular conditions affecting the limbs, aorta, and peripheral arterial system.
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