Phlebitis & Blood Clots

What Are Phlebitis and Blood Clots?

Phlebitis (fle-BYE-tis) is the medical term for inflammation of a vein. When this inflammation is caused by a blood clot, the condition is called thrombophlebitis. Blood clots can form in veins near the skin’s surface (superficial thrombophlebitis) or in the larger, deeper veins of the body (deep vein thrombophlebitis, or DVT). While phlebitis most commonly occurs in the leg veins, it can also develop in veins of the arms, particularly after IV placement or injury.

Understanding the difference between superficial and deep phlebitis is important because the conditions have very different levels of severity and treatment approaches.

Superficial Phlebitis

Superficial phlebitis affects veins just below the skin’s surface. The condition is usually localized and, with proper care, typically resolves within a few weeks. You may notice:

• A visible red streak along the course of the vein
• The vein may feel hard, warm, and tender to the touch — like a firm cord under the skin
• Mild swelling and redness around the affected area
• Itching or a burning sensation over the vein

While superficial phlebitis is rarely serious on its own, it is important to have it evaluated by a medical professional. In some cases, superficial phlebitis can extend into the deep venous system or may indicate an underlying condition that increases clotting risk [1].

Deep Vein Thrombophlebitis

Deep vein thrombophlebitis is a more serious condition in which blood clots form in the large veins deep within the legs. The major concern with deep vein thrombophlebitis is that a clot can break free, travel through the bloodstream, and lodge in the lungs — a life-threatening condition called pulmonary embolism (PE).

Deep vein thrombophlebitis requires prompt medical attention and treatment to prevent clot progression and reduce the risk of pulmonary embolism. For more information about this condition, see our dedicated page on Deep Vein Thrombosis (DVT).

Symptoms

The symptoms of phlebitis and blood clots depend on whether the condition affects superficial or deep veins.

Superficial Phlebitis Symptoms

• A slow-developing tender, red area along a superficial vein
• A long, thin red streak visible on the skin surface following the course of the vein
• The affected vein feels hard, warm, and rope-like under the skin
• Skin around the vein may be itchy, swollen, and warm
• Throbbing or burning sensation in the affected area
• Symptoms are often worse when the leg is lowered, especially first thing in the morning
• A low-grade fever may develop

Deep Vein Thrombophlebitis Symptoms

• Significant swelling in the affected limb
• Pain that may feel like deep cramping or a persistent ache
• Warmth and redness over a larger area of the leg
• Skin discoloration — the leg may appear reddish or bluish
• The affected leg may feel heavy or fatigued
• Pain that worsens with standing or walking

Important: In approximately half of all DVT cases, there are no noticeable symptoms. This is why medical evaluation is essential if you have risk factors for blood clots.

Phlebitis After IV Placement

Phlebitis can develop at the site of a peripheral intravenous (IV) line. Symptoms include soreness, redness, and tenderness along the vein where the IV was inserted. If an infection develops at the site, additional symptoms may include fever, increasing pain, drainage, and breakdown of the surrounding skin.

Causes and Risk Factors

Blood clots and vein inflammation can develop for many reasons. In general, anything that damages a vein, slows blood flow, or increases the tendency for blood to clot can trigger phlebitis. Common causes and risk factors include:

• Prolonged inactivity: Sitting or lying still for extended periods — such as during long car rides, flights, or bed rest — allows blood to pool in the legs, creating conditions favorable for clot formation.
• Sedentary lifestyle: Lack of regular physical activity reduces the muscle contractions that help pump blood through the veins.
• Recent surgery or injury: Trauma to veins from surgery, injury, or IV placement increases the risk of clot formation.
• Obesity: Excess weight increases pressure on the veins in the legs and pelvis.
• Smoking: Damages blood vessel walls and affects normal blood clotting.
• Cancer: Some cancers increase the levels of clotting factors in the blood. Certain cancer treatments also raise clotting risk.
• Hormone therapy or birth control pills: Estrogen-containing medications increase the blood’s tendency to clot.
• Pregnancy: Increases pressure on pelvic and leg veins and alters blood clotting factors.
• Varicose veins: Damaged vein valves create areas of slow blood flow where clots are more likely to form.
• Blood-clotting disorders: Inherited conditions that make blood clot more readily.
• Previous history of phlebitis or DVT: Having had phlebitis or blood clots significantly increases your risk of recurrence.
• Age: Risk increases with advancing age, particularly after 60.

Diagnosis

Physical Examination

Your healthcare provider will examine the affected area, looking for signs of inflammation, tenderness, warmth, and swelling. They will ask about your symptoms, medical history, and any recent activities or events that may have triggered the condition.

Diagnostic Tests

• Duplex Ultrasound: The primary test for evaluating phlebitis and blood clots. A small handheld probe is pressed gently against the skin to visualize blood flow through the veins and detect clots or blockages. This test is painless, non-invasive, and highly accurate for identifying clots in the larger veins of the upper leg.
• D-dimer Blood Test: Measures a substance released when blood clots break down. Elevated D-dimer levels suggest active clotting, though the test is not specific enough to confirm a diagnosis on its own.
• Venography: In rare cases where ultrasound results are inconclusive — particularly for clots in the smaller, more distal veins — a venogram may be performed. Contrast dye is injected into a vein in the foot, and X-rays track the dye as it flows up through the leg veins, revealing any blockages.
• CT or MRI: Cross-sectional imaging may be used to evaluate the extent of deep vein thrombosis or to check for pulmonary embolism.

Treatment

Treatment for phlebitis and blood clots depends on whether the condition is superficial or deep.

Superficial Phlebitis Treatment

• Warm compresses applied to the affected area to relieve inflammation
• Elevation of the affected limb to reduce swelling
• Anti-inflammatory medications (NSAIDs) to reduce pain and inflammation
• Compression stockings to improve blood flow and reduce swelling
• Walking and gentle activity to promote circulation

Most cases of superficial phlebitis resolve within 1-2 weeks with conservative treatment.

Deep Vein Thrombophlebitis Treatment

Deep vein thrombophlebitis requires more aggressive treatment:

• Anticoagulant medications (blood thinners) to prevent the clot from growing and reduce the risk of pulmonary embolism
• Thrombolytic medications (clot busters) may be used in severe cases to dissolve large clots
• Compression stockings to manage swelling and prevent post-thrombotic syndrome
• IVC Filter: For patients who cannot take blood thinners or who develop clots despite anticoagulation, an inferior vena cava (IVC) filter may be placed. This small device is inserted into the major vein leading to the heart, where it catches blood clots before they can reach the lungs.

Prevention

You can reduce your risk of phlebitis and blood clots by:

• Staying physically active and exercising regularly
• Moving frequently during long periods of sitting — take breaks to walk and stretch
• Staying hydrated, especially during travel
• Wearing compression stockings if recommended by your doctor
• Maintaining a healthy weight
• Quitting smoking
• Following post-surgical activity guidelines provided by your healthcare team
• Discussing your clotting risk with your doctor before starting hormonal medications

Why Choose Preferred Vascular Group?

At Preferred Vascular Group, our vascular specialists provide comprehensive care for phlebitis and blood clots, from diagnosis through treatment and ongoing management. We offer:

• Rapid diagnostic evaluation with in-office duplex ultrasound
• Expert treatment including anticoagulation management and IVC filter placement
• Coordinated care with your primary care physician and other specialists
• Preventive counseling to reduce your risk of recurrence
• Eight convenient locations across Georgia and Ohio for accessible, expert care

If you are experiencing symptoms of phlebitis or blood clots, prompt evaluation is important. Contact our office to schedule an appointment with one of our vascular specialists.

References

1. Superficial Thrombophlebitis. StatPearls, StatPearls Publishing, 2024. NCBI Bookshelf
2. Defined I, et al. “Superficial Venous Thrombosis: A Comprehensive Review.” Current Cardiology Reports, 2024. PMC
3. Di Nisio M, et al. “Treatment for superficial thrombophlebitis of the leg.” Cochrane Database of Systematic Reviews, 2018. PubMed