Swelling in the upper leg or thigh is not water retention / edema instead it can occur for a number of reasons. Let’s see some possible causes of thigh swelling.

Refer to Fluid Retention in Legs - Peripheral Edema to learn about peripheral edema.

Diabetic Muscle Infarction

Diabetic muscle infarction (DMI) is a very rare but serious complication of longstanding diabetes mellitus. In most cases, it occurs in diabetic patients with established vascular disease and systemic inflammation. It does not cause any systemic signs of infection such as fever, aches, chills, nausea and vomiting. Common symptoms of diabetic muscle infarction include intense pain and localized swelling in the lower body parts, especially thigh swelling and pain, which causes limitation in the range of motion.

Diabetic muscle infarction often resolved spontaneously after some times without much intervention. However, recurrences of it are common either in the same or opposite limb. Applicable treatments include managing pain and swelling in upper and lower leg or other sites, restricting activities and gentle physical therapy.


A boil is a deep localized infection of the hair follicle caused by an accumulation of pus and dead tissue, resulting in painful swollen area on the skin. A carbuncle is formed when several boils cluster together and create one deep abscess.

Boils occur most often on the face, back of the neck, armpits, thighs and in other moist areas of the body, although may occur anywhere on the body. Boils in the thigh will cause reddish swelling in thighs around the affected area.

They are reddish swellings around a hair follicle about 5 to 10mm in size that are firm, warm, and painful. They will form a visible yellow or white tip at the center of the lump when they are ready to be drained out through the skin. Some sufferers may experience fever, swelling around the boil, swollen lymph nodes, and fatigue.

Lipoma (lipoma of the thigh)

Lipoma is a benign tumor made of soft fatty tissue. It is often movable and painless. It can size from as small as below 1cm to as large as 6cm or more in diameter. Some common sites of lipoma are the upper thighs, upper arms, torso, neck and armpits.

Lipoma can occur at any age, but are most common in middle age people ranged from 40 to 60 years old. Swelling may be seen at the location of tumor such as upper leg swelling or swelling in the arm.

Certain types of lipoma may develop in the upper leg and cause thigh swelling includes:

  • Intradermal spindle cell lipoma This type of lipoma mostly occurs in women and can develop on the head and neck, trunk, and upper and lower extremities.
  • Superficial subcutaneous lipoma This is the most common type of lipoma, forms just below the superficial skin. It may occur anywhere in the body where fat is located, especially on the trunk, thighs and the forearms.

Most cases of lipoma do not need surgical removal, unless the area becomes painful, infected, or restricts movement, or for cosmetic reasons.

Thigh strain / injury

A strain is a tear in the muscle that can ranges from a very mild tear to complete rupture. Thigh strain is a common injury, especially among athletes. It usually occur when the thigh muscle is stretched excessively, tearing the muscle fibers.

Common sites of thigh muscle strains are the hamstring and quadriceps muscles groups since they cross both the hip and knee joints.

Treatment of muscle strains is depended on the severity of the injury which ranges from grade 1, 2 to 3.

  • Symptoms of grade 1 thigh strain include sudden feeling of slight pain in the thigh, walking discomfort, and tightness in thigh.
  • Grade 2 thigh strain causes pain on walking, thigh swelling, mild bruising, pain on the affected area, unable to bend the knee fully, and sudden sharp pain when running or jumping.
  • Symptoms of grade 3 thigh strain are severe pain in the thigh, walking difficulty, very serious swelling in thighs, and visible bruising.

Most thigh muscles strain can be treated with the R.I.C.E (rest, ice, compression, elevation) procedure. Compression stockings should be helpful to reduce the thigh swelling. However, you should consult with a sports injury professional when needed. If you suspect your injury is in the grade 3, see a sports injury specialist immediately.

Once a muscle strain occurs, the muscle can get injured easily thus it is important to let the muscle heal properly and to follow preventive protocols.

Superficial thrombophlebitis

Superficial thrombophlebitis is another possible cause of thigh swelling. It is an inflammation and thrombosis (blood clot) of superficial veins, commonly in the lower extremities. Superficial thrombophlebitis is not like or as serious as deep vein thrombosis.

Many conditions can trigger the inflammation of the vein, even a slight injury to the vein. Having varicose veins, intravenous injection, veins disorder, venous insufficiency, abnormalities of blood clotting factors such as using contraceptive pill, using HRT, cancer, smoking, and pregnancy, and stasis of blood e.g. prolong standing or sitting, after major surgery, etc. all increase the risk of superficial thrombophlebitis.

Symptoms of superficial thrombophlebitis include swelling, redness, tenderness, hardness, and small lump at the site of the affected vein. Some also develop a fever.

Superficial thrombophlebitis is not a serious disorder, most cases resolve within 2 to 6 weeks without medical intervention. Stay active, raise the affected leg and wear compression stockings all may help to ease the symptoms. Anti-inflammatory tables, creams or gels can be taken or applied when needed to reduce any pain.

Rarely, some patients may develop complication from superficial thrombophlebitis including infection, blood clot extension (which may lead to DVT especially if the superficial thrombophlebitis is in the upper thigh or the groin), etc. Look for medical attention immediately if you suspect any development of complication.

Deep vein thrombosis

Deep vein thrombosis (DVT) is a type of thrombophlebitis in which blood clots are formed in the deep veins.

Deep vein thrombosis commonly affects the leg veins or the deep veins of the pelvis, leading to pain and swelling in thigh and leg, although it can form in the veins of the arms too. Common symptoms of a DVT are pain, swelling, redness, and warm of the leg and the surface veins may get dilated however some cases of DVT may present no symptoms at all.

A combination of decreased flow rate of the blood, damage to the blood vessel wall and an increased tendency of the blood to clot (hypercoagulability) is said to be the main cause of this disorder.

Other medical conditions that may lead to DVT, such as compression of the veins, physical trauma, cancer, infections, certain inflammatory diseases and specific conditions such as stroke, heart failure or nephritic syndrome.

Surgery, hospitalization, immobilization, smoking, obesity, age, certain drugs, pregnant, women in postnatal period and inborn tendencies to form clots all increase a person’s risk for DVT.


A group of uncommon disorders characterized by inflammatory destruction of blood vessels (both arteries and veins) are referred to as vasculitis. Depends on the type of vasculitis, leg and thigh swelling may be seen.

The actual cause of vasculitis diseases is often unknown. But, immune system disorder and inflammation of blood vessels are common aspects.

The symptoms of vasculitis vary depended on the form of vasculitis one has, the organs affected and how severe the disease is. Some possible symptoms include:

  • Systemic symptoms: fever, weight loss, fatigue, pain
  • Organs / body system specific symptoms: skin changes, muscle aches, arthritis, short of breath, bloody cough, headache, stroke, hypertension, abdominal pain, bloody stool, itchy burning eyes, swelling, etc.

Treatments are directed toward reducing the inflammation of the blood vessels, suppressing the immune system, and improving the function of affected organs. These include cortisone-related medications, immune suppression drugs, and other medications to improve the function of affected organs.

There are still many other possible causes of swelling in upper leg. If you notice any unexplained thigh swelling, consult with your doctor as soon as possible.