Do not wait to see whether the symptoms disappear. Seek emergency medical attention immediately if you suspect pulmonary embolism.

5. Ten Warning Signs and Symptoms of a Blood Clot in the Leg

The symptoms of DVT can resemble those of ordinary muscle injuries or other medical conditions.

Nevertheless, certain warning signs deserve particular attention, especially when they appear suddenly, affect only one leg, or occur in someone with known risk factors.

1. Swelling in One Calf or Leg

Unexplained swelling in one calf is one of the most recognizable warning signs of deep vein thrombosis.

A clot can partially or completely obstruct a deep vein, preventing blood from returning efficiently toward the heart.

As blood accumulates behind the obstruction, pressure inside the affected veins increases. Fluid can then move into surrounding tissues, resulting in swelling.

You may notice that:

• One calf looks visibly larger than the other.

• Your ankle or foot becomes swollen.

• Your shoes feel tighter on one foot.

• Your lower leg feels unusually heavy.

• Swelling becomes more noticeable after standing or walking.

Sometimes, swelling extends from the calf toward the knee or thigh, particularly when the clot affects a larger vein.

According to the NHS, swelling in one leg is a common symptom of DVT, although both legs can occasionally be affected.

It is especially important to seek medical assessment when swelling appears without an obvious explanation and is accompanied by pain, tenderness, or warmth.

Not every swollen leg is caused by a blood clot. Other possible explanations include muscle injuries, infections, heart failure, and chronic venous insufficiency.

However, because DVT can cause life-threatening complications, unexplained one-sided swelling should never be ignored.

NHS+1

2. Persistent Pain in the Calf

러닝종아리통증, 단순 근육통일까? 병원 가야 하는 신호 : 성모탑정형외과 |

Pain in the calf muscle is another common symptom of a deep vein blood clot.

The discomfort may begin as a mild ache before becoming more noticeable over time.

Some people describe it as:

• A deep muscular cramp.

• A persistent throbbing sensation.

• A feeling of tightness in the calf.

• Tenderness when walking.

• Pain that becomes more noticeable when standing.

The pain may occur even when you have not exercised or performed any strenuous physical activity.

In some cases, the affected calf may feel painful when you walk or put weight on your leg.

Unlike ordinary muscle soreness following exercise, DVT-related discomfort may be accompanied by swelling, warmth, or changes in skin color.

The Mayo Clinic identifies leg pain, cramping, and soreness, often beginning in the calf, as common DVT symptoms.

However, pain alone cannot establish whether a blood clot is present.

Other conditions that may produce similar symptoms include:

• A strained calf muscle.

• Achilles tendon injuries.

• Hamstring injuries.

• Sciatica.

• Varicose veins.

• Peripheral artery disease.

• Muscle inflammation.

The important warning sign is unexplained pain, particularly when it affects one leg and occurs alongside other symptoms of DVT.

3. Pain or Discomfort When Walking

Some people notice that their calf becomes uncomfortable when walking or standing.

This may happen because the affected leg is already swollen or because the surrounding tissues are under increased pressure.

The pain can make ordinary activities more difficult, including climbing stairs, walking to work, or standing for extended periods.

However, pain during walking is not specific to DVT.

For example, peripheral artery disease can also cause calf discomfort during physical activity because the muscles do not receive sufficient oxygen-rich blood.

A muscle injury may produce pain when the affected muscle contracts.

The combination of unexplained one-sided swelling, tenderness, and warmth is more concerning than walking discomfort alone.

If these symptoms develop suddenly, particularly after surgery, prolonged immobility, or long-distance travel, seek prompt medical evaluation.

4. Calf Tenderness When Touched

Deep Vein Thrombosis: What is it, Causes, Prevention, and More | Osmosis

Another possible sign of DVT is tenderness in the affected calf.

You may notice discomfort when touching or gently pressing the area.

The tenderness may be localized to one section of the lower leg, although some people experience more widespread discomfort.

Inflammation and increased pressure in the affected tissues can contribute to the sensation.

However, calf tenderness is not exclusive to blood clots. Muscle strains, bruising, infections, and tendon problems can also cause localized pain.

A particularly important distinction is that you cannot diagnose DVT by squeezing your calf.

Do not repeatedly press, massage, or manipulate a painful leg to determine whether a clot is present. Physical examination alone cannot reliably confirm or exclude the condition.

Medical assessment and appropriate diagnostic testing are necessary.

5. Redness or Discoloration of the Skin

Deep Vein Thrombosis (DVT)

Changes in skin color may occur when a blood clot interferes with normal circulation.

The affected area may appear:

• Red.

• Reddish-purple.

• Bluish.

• Darker than the surrounding skin.

The exact appearance varies according to the person's natural skin tone and the location of the clot.

On lighter skin, redness may be easier to recognize. On darker skin, discoloration may appear purple, brown, or simply darker than the surrounding area.

The skin may also look stretched or shiny when swelling is present.

It is important to understand that redness is not always present in DVT. Some people experience swelling and pain without noticeable changes in skin color.

Redness can also occur with cellulitis, an infection of the skin and underlying tissues, or superficial thrombophlebitis.

If a red or discolored area develops alongside unexplained swelling and pain in one leg, seek medical evaluation rather than assuming it is a minor skin problem.

6. Unusual Warmth in the Lower Leg

Thrombophilia: Causes, Treatments and Medication Options

A blood clot can trigger inflammation in the affected vein and surrounding tissues.

As a result, the skin over the affected area may feel warmer than the skin on the opposite leg.

You may notice that one calf feels unusually warm when you place your hand over it.

This warmth may occur together with:

• Swelling.

• Redness or discoloration.

• Pain.

• Tenderness.

• A sensation of tightness.

The warmth may be limited to a small area or involve a larger portion of the lower leg.

Although this symptom can be helpful when identifying possible DVT, it is not definitive.

Skin infections and superficial vein inflammation can also cause warmth.

The CDC lists warmth among the common signs of DVT and recommends seeking medical attention when symptoms suggest a possible blood clot.

CDC+1

7. A Heavy or Tight Feeling in the Leg

Some people with DVT describe their affected leg as feeling unusually heavy.

This sensation may occur because blood flow is obstructed and fluid accumulates in the surrounding tissues.

You might feel as though your calf is stretched, swollen, or unusually tight.

The discomfort may become more noticeable after standing for a long time.

In some cases, the leg may feel tired even after relatively little physical activity.

A heavy sensation is also common in people with varicose veins and chronic venous insufficiency. Therefore, it should not be considered proof of DVT.

However, if the heaviness develops suddenly and is accompanied by swelling, pain, or warmth in one leg, it deserves prompt medical attention.

8. Pain or Swelling in the Upper Thigh

Phác đồ điều trị huyết khối tĩnh mạch sâu chi dưới theo ý kiến của bác sĩ chuyên khoa mạch máu

Although many people associate DVT with the calf, blood clots can also develop in the deeper veins of the thigh or pelvis.

When this happens, symptoms may extend beyond the lower leg.

You might experience:

• Pain along the inner thigh.

• Swelling around the upper leg.

• Discomfort near the groin.

• A heavy sensation extending from the thigh toward the calf.

• Swelling affecting most of one leg.

Clots in the femoral or pelvic veins can interfere with circulation over a larger area.

In some cases, a person may initially experience thigh pain without obvious calf discomfort.

Pelvic vein thrombosis may occasionally produce lower abdominal or pelvic pain.