Swollen ankles and blood clots: How unhealthy veins could kill you

Telegraph

24-07-2025

Whilst many of us do our best to take care of our brain, heart, skin and gut, we often take our veins for granted. Perhaps we think they'll look after themselves. Yet, there are thousands of miles of veins running through our bodies – circulating blood back to our heart and lungs for replenishment and waste removal – and there can be serious consequences if they're unhealthy. Think swollen ankles, leg ulcers, throbbing pain and – in the most severe cases – death.
President Donald Trump was recently diagnosed with chronic venous insufficiency (CVI) – a condition which causes blood to pool in the veins – after noticing 'mild swelling' in his lower legs. The White House physician assured reporters that President Trump's condition is 'benign'. However, if ignored, CVI can lead to serious complications including leg ulcers and pulmonary embolism (PE).
So, what are the common venous diseases, how serious are they and what should we be doing to protect our veins?
Varicose veins
In our veins, there are valves that act as one-way doors, ensuring our blood flows in the correct direction towards the heart. They're particularly important in the legs, where our blood needs to travel against gravity. Varicose veins occur when these valves don't work properly.
The blood builds up and puts pressure on the veins – this is called 'venous reflux' – which causes them to swell, twist and bulge. Varicose veins typically appear just under the skin on our legs, feet or ankles. Smaller, web-like veins sometimes form around them and these are called spider veins. These develop in smaller blood vessels, closer to the skin's surface, and tend to be asymptomatic.
'People talk about varicose veins quite dismissively. In the past, they were seen as a purely cosmetic problem, however thanks to a shift in research in the 1980s, we now know that's not the case,' says Professor Mark Whiteley, a consultant venous surgeon and founder at The Whiteley Clinic. Whilst they're not a major problem for most people, they can sometimes cause complications such as blood clots or leg ulcers.
Symptoms may include aching, heaviness, itching or burning in the legs, as well as visible bulging veins. You should see a GP if you have varicose veins and these symptoms, or ask for an urgent appointment if they're bleeding.
Chronic venous insufficiency
Similarly, CVI is a condition where the veins in the legs struggle to pump blood back to the heart, 'resulting in reverse flow which causes inflammation, typically around the ankles,' Whiteley explains. 'The trouble is that CVI is a catch-all term which basically means that the valves aren't working. This could be in the superficial veins near the skin surface or in the deep veins which run through your muscles.' Varicose veins may be a symptom of CVI.
Risk factors include age, prolonged inactivity and family history. CVI may also occur in people who have previously had deep vein thrombosis (DVT – see more on this condition below) and key symptoms include swollen, discoloured, achy, tired or tingly legs.
'If you have swollen ankles and you think you could have CVI, it's really important to get a scan because the treatments and outcomes are phenomenally different depending on whether you have CVI in the deep or superficial veins,' Whiteley explains. 'It becomes a very different problem if the deep veins are involved, but fortunately – unless you've had DVT in the past – it's usually superficial and can almost always be properly treated.'
Blood clots
When blood clots form in your veins, the condition is called 'thrombosis'. There are three key reasons why this happens, known as Virchow's triad, Whiteley explains, and these are 'changes in the blood, changes in the blood flow, and changes in the blood wall'.
Factors that 'change your blood' include smoking cigarettes and taking the contraceptive pill, Whiteley says. The nicotine in cigarettes causes blood vessels to constrict, whilst also damaging the inner lining of veins and causing inflammation. Meanwhile, in the pill, oestrogen is known to make blood more 'sticky', therefore increasing the risk of clotting.
Damage to the vessel wall can occur because of 'inflammation, tumours, radiation, injury, or surgery', whilst abnormal blood flow may occur when 'you sit down or don't move for long periods of time,' Whiteley explains.
If a blood clot forms below the knee or in a superficial vein (superficial thrombophlebitis), it's not generally considered as dangerous and it may resolve itself, Whiteley says. However, it becomes more concerning if the clot forms in a vein behind the knee or, worse, between your knee and groin or pelvis. This is called a DVT…
Deep vein thrombosis (DVT)
…Which is a serious condition where a blood clot forms in a deep vein. 'If a clot forms between your knee and groin, or in your pelvis, there's a chance it travels to the heart, is pumped to the lungs and causes a pulmonary embolism [PE],' Whiteley explains. A PE can lead to serious complications including respiratory distress and cardiovascular issues.
Symptoms of DVT include throbbing pain or swelling in one leg, swollen veins that are hard or sore when you touch them and warm skin around the painful area. You're more likely to get DVT if you're over 60, have varicose veins, are overweight or have had the condition before.
'In the long term, DVT can also damage the deep veins. You can end up with a long-term swollen, discoloured leg, often with ulcers, which is called post-thrombotic syndrome,' Whiteley says.
You should ask for an urgent GP appointment if you think you have DVT, or call 999 if you have symptoms such as swelling and breathlessness or chest pain.
Venous leg ulcer
Venous leg ulcers are open and painful sores which usually develop on the inside of the leg, between the knee and the ankle. You may develop a venous leg ulcer if you've previously had DVT, have varicose veins, are older, overweight or have difficulty walking and symptoms include pain, itching and swelling.
'DVT can cause leg ulcers in the long term because the blood clots can damage valves in the veins, leading to inflammation which damages the skin,' Whiteley explains, whilst varicose veins also increase inflammation in the leg.
Venous leg ulcers are unlikely to get better on their own and usually require specialist medical treatment to ensure they don't become infected or lead to tissue damage.
How to look after your veins
Walk, run and swim
'The best thing you can do for your veins is exercise,' Whiteley says. Exercise improves circulation which helps to propel blood through the veins, especially in the legs, back towards the heart. A 2018 study by researchers at Liverpool John Moores University found that training improves vascular function and supports the production of nitric oxide, which helps to relax the smooth muscles in vein walls.
Whiteley says walking, running and swimming are the best exercises for healthy veins. 'If you're not able to do these, even sitting in front of the TV and stimulating your legs by elevating or pumping them [flexing your feet up and down] is going to help reduce pressure on your veins. Anything that gets the blood flowing,' he explains.
Compression stockings
Whilst they're not the most fashionable accessory, Whiteley recommends graduated compression stockings to support your veins. They are designed to improve blood flow in the legs and improve circulation by applying gentle, graduated pressure – tighter at the ankle and decreasing up the leg.
'If you're not able to move your legs a lot, compression stockings will really help to stimulate the blood flow,' Whiteley says. They're particularly useful when you're sitting for a long period of time, for example during a flight. They can also help to prevent or manage varicose veins.
Micro-purified flavonoid fraction (MPFF)
Whilst Whiteley says there aren't any major dietary changes you can make to protect your veins, there is 'some evidence' that MPFF can support vein health. It's a medication composed of different flavonoids – primarily diosmin which is found in citrus fruits. A 2019 review in Advances in Therapy says it can help to alleviate leg pain, heaviness, sensations of swelling and cramps.
'It won't reverse damage to your veins but it can take away some of the discomfort, pain and inflammation,' Whiteley says. 'Most nutritional measures may provide a little bit of help but none of them are curative or preventative.'
Drink lots of water
When you're sufficiently hydrated, your blood is thinner which means it's easier for your heart to pump and circulate it through the veins. 'When you're dehydrated, your blood constituents change which means you're more likely to get a clot,' Whiteley explains.
'The simple way to tell if you're drinking enough is to look at your urine,' he says. 'If it's a straw colour, you're drinking enough.' Whilst drinking enough water doesn't make your valves any stronger or work any better, it ensures that your blood is circulating efficiently.
Avoid smoking
Smoking damages blood vessels and reduces overall circulation. It can also thicken the blood and reduce oxygen levels, increasing the likelihood of blood clots forming in the veins.
One study in the Journal of Thrombosis and Haemostasis found a positive association between smoking and DVT among middle-aged men and women. They discovered that former smokers had the same risk of DVT as those who had never smoked, highlighting the potential benefits of giving up cigarettes.
FAQs
What do the colour of your veins mean?
'Your veins are white and completely colourless, so you're actually seeing the blood in them,' Whiteley explains.
He says the colour depends on 'how much tissue is between the top layer of your skin and the blood in the vein'. If it looks red, it means your vein is 'very near the surface of the skin and has a very thin wall'. If it's a purple or blue colour, your vein is 'a bit deeper and the vein wall is a bit thicker' and if it's green, it means that 'the vein wall is even thicker and the vein is even deeper'.
Does dry brushing help with vein health?
Dry brushing does not help with vein health, Whiteley says. However 'it's very good for your lymphatics' which are a network of vessels, organs and tissues that play a vital role in your body's immune system.
'I'm a great advocate of dry brushing for drainage, and to help with lymphoedema and cellulite too. Ensure you brush in the right direction of your lymphatics,' Whiteley advises.
Does crossing your legs make varicose veins worse?
'No. This is a myth that originated from hospitals when they thought that patients crossing their legs on the bed gave them DVT,' Whiteley says. In fact, it was the patient's operation or illness that caused DVT. The idea that crossing your legs makes varicose veins worse is 'completely incorrect,' Whiteley concludes.