Varicose veins are a common condition affecting women and men, particularly in middle and older age. It is often genetic and can also be caused or exacerbated by obesity, smoking, pregnancy, menopause, hormones, lack of physical activity, a prior leg injury, and ageing.

 Varicose veins occur when the walls or valves within the superficial veins (usually of the legs) become weakened or otherwise damaged and lead to an array of symptoms including leg heaviness, fatigue, aching, pain, swelling, redness, heat, skin dryness and thickening, rashes, and sores on the legs. It also results in the characteristic unsightly blue-purple veins visible under the skin and which may also bulge and become twisted. 

Varicose veins can also cause (or result from) blood clots.


Varicose Veins and Blood Clots

When veins bulge and/or become twisted, or the valves within the veins fail, the flow of blood through them can pool or become sluggish. Slow-flowing or stagnant blood can quickly clot, as the platelets within the blood clump together. This is a natural, normal physiological response to prevent haemorrhage if a blood vessel is broken. When varicose veins are present, the body may mistake the damaged vein for a wound and create a blood clot in error. 

A clot within an intact vein is abnormal and can become a medical concern as it blocks the healthy blood flow and causes further blood stagnation. 

A blood clot in a varicose vein is called superficial thrombophlebitis, or superficial venous thrombosis (SVT). These clots occur only in the superficial veins – the same veins that can become varicose. They are not the same as a DVT.


Superficial venous thrombosis (SVT) in the legs can cause:

  • Swelling of the skin and fat adjacent to the varicose vein
  • Redness over the area
  • Tenderness and lumpiness
  • Hardening of the vein
  • Sharp, severe pain along the vein


What is DVT?

Deep Vein Thrombosis or DVT is a blood clot that develops in a deep vein of the leg. This is not a vein that can become varicose.

DVT symptoms and signs include:

  • Swelling in the affected leg
  • Cramping pain in the calf or behind the knee
  • Warmth or a burning sensation
  • Redness or skin discolouration
  • Sometimes there are no discernible symptoms
  • A DVT can break off (embolus) and travel to the lungs. This causes a pulmonary embolism (PE). 


The causes of DVT include many of those that also cause varicose veins. Other specific risk factors for DVT that are
not risk factors for varicose veins include:

  • Surgery/Prolonged Bed Rest
  • Heart Failure – Due to limited heart and lung function, and more sluggish blood flow.
  • Inflammatory Bowel Disease (Crohn’s disease, ulcerative colitis)
  • Cancer – A DVT can be an early sign of cancer. Between 5-25% of cancer patients also have blood clots and 10% of people with a DVT or PE will be diagnosed with cancer within a year. The genetic changes that cause cancer increase clotting activation in the body and tumours also release chemicals that trigger clotting.

A pulmonary embolism (PE) is a medical emergency and is potentially life-threatening. The blood clot from the deep vein travels and blocks a blood vessel in the lung.

Symptoms of a DVT that has embolised to the lungs include:

  • Sudden shortness of breath
  • Worsening chest pain or discomfort, especially when coughing or breathing deeply
  • Lightheadedness or dizziness
  • Rapid breathing
  • Rapid pulse
  • Coughing up blood


DVTs can also cause direct damage to the deep veins, reducing or blocking the blood flow and leading to skin ulceration.
Emboli from DVTs can also travel to the brain or heart and cause a stroke or heart attack.


DVT & Varicose Veins:

DVT is not often associated with varicose veins.

There are important differences between a DVT and an SVT. Unlike a DVT, clots in varicose veins rarely break off and travel to other parts of the body. They very rarely have significant systemic implications. 

The issue is more that with similar symptoms, it can sometimes be difficult to determine for oneself whether symptoms are caused by varicose veins or a DVT. DVTs require immediate and ongoing treatment, sometimes for months, with blood thinners that have significant side effects. Failure to quickly treat a DVT can be life-threatening.

Varicose vein clots do not require these medications.

If varicose veins are severe, however, there may be an increased risk of a DVT also occurring, especially if you are sedentary for long periods and when travelling/flying. Injuries to the leg can cause varicose veins to increase the risk of developing a DVT.


Prevention Tips for DVTs and Varicose Veins

  • Avoid sitting or standing for long periods
  • Don’t smoke
  • Manage weight and maintain a healthy BMI
  • Exercise and move regularly
  • Elevate your legs 
  • Wear compression stockings/socks when flying or travelling for long periods in a car
  • Have varicose veins medically assessed and treated as appropriate

If you have any concerns about the blood vessels in your legs, especially if some of your symptoms may suggest a DVT, it’s important to see your doctor so they can diagnose whether the condition is caused by varicose veins, a possible DVT, or another condition which may cause similar symptoms (e.g., peripheral artery disease, cellulitis, vasculitis, acute arterial occlusion, nephrotic syndrome, venous stasis, lymphoedema, and others.


Minimally Invasive Varicose Vein Treatment in Sydney

Crows Nest Cosmetic & Vein Clinic is a walk-in, walk-out clinic offering effective minimally invasive varicose vein treatments. Dr Nicole James is our in-house expert in advanced modern approaches to vein treatment and she will assess your case and recommend sclerotherapy, microsclerotherapy, or endovenous laser ablation (or a combination thereof) as appropriate.

Book your consultation now! No GP referral is required. Vein treatments at our clinic are eligible for Medicare Rebates.

Contact us via our online contact form,  or call (02) 9906 1555 or email [email protected].