Causes of Thread Veins

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Thread veins are also known as spider veins for their web like appearance, or for the lion hearted, telangiectasia. The condition presents as a network or web of red or blue blood vessels on the surface of the skin. It typically occurs on the face, legs, and cheeks, and can vary in size. The first and most important point to make about this condition is that it is generally harmless, but can, on rare occasions, be a symptom of other vascular issues. If you do happen to notice any thread veins, it’s always best to consult with your doctor to rule out this possibility.

Blood vessels vary in size and function throughout the body. The smallest of these are capillaries, which become damaged to form thread veins. Capillaries are very fine, often only just wide enough to let one blood cell through at a time. Capillary walls are also often only one or two cells thick, with a minimal amount of muscle fibre, so you can see how they might become easily damaged! Blood vessels are also quite elastic, and spend a lifetime relaxing and constricting, with age for example, this elasticity is lost, leading to the condition. Capillaries form a vast network linking other blood vessels, which contributes to the web like appearance of the condition when capillaries are affected. Smaller veins are also affected in the condition.

What factors affect the likelihood of getting thread veins?

A number of factors contribute to the formation of thread veins, but fundamentally they all revolve around placing pressure on capillaries and finer veins, resulting in damage or expansion. These include:

  • Genetic Inheritance
  • Age
  • Gender-Related Factors
  • Varicose Veins
  • A Sedentary Lifestyle
  • Leg Injuries
  • Occupation
  • Prolonged Sun Exposure
  • Obesity
  • Alcohol
  • Abdomen Tumours or Liver Disease
  • Chemotherapy/Radiotherapy


The ageing process is one of the main factors affecting the development of thread veins. Skin becomes thinner and more prone to damage as you age. The older you become, the less subcutaneous fat (fatty tissue under the surface of the skin) you have, meaning that blood vessels can become more visible as they are now closer to the surface. These vessels experience a certain amount of ‘wear and tear’ as time goes on, often leading to conditions such as thread veins. They usually appear during middle age and older, though it is not at all uncommon for people in their twenties to get them. In fact, it is thought that around 20% of twenty year olds do indeed have thread veins.


Women are far more likely to develop thread veins, and some statistics suggest that up to 50% of women in the UK will develop them in their lifetime. Hormonal fluctuations and pregnancy are the culprits in this instance, as both trigger a number of physiological changes including the relaxation of vascular walls. Pregnancy in particular places a lot of stress on blood vessels in and around the pelvic regions, and multiple pregnancies significantly increases the likelihood of developing either thread or varicose veins.

Gender-Related Factors

Thread veins are much more likely to occur in women than in men, with up to half of women experiencing thread veins at some point in their lives. Thread veins are more common in women for a number of reasons. Pregnancy is one of them. During pregnancy, the uterus puts pressure on the veins in the pelvic area due to having to accommodate the growing baby, weakening the vein walls and damaging the capillaries, causing them to enlarge and thus be noticeable. Thread veins are more common in women who have been pregnant several times as opposed to women who have never been pregnant. They usually disappear after childbirth.

Hormone fluctuations are another factor, particularly fluctuations in oestrogen levels. These changes in hormone levels tend to occur during puberty, pregnancy and the menopause. Female hormones have a certain effect on the walls of veins which makes them weaker and more likely to become damaged, leading to thread veins.

There is also a slight issue regarding oral contraceptives. The pill contains synthetic versions of female hormones, oestrogen being one of them. Although the hormone is synthetic, it still has the same effect as the natural one, relaxing the vein walls and hence sometimes contributing to thread veins.

Varicose Veins

A lot of the time, thread veins can develop alongside varicose veins. They are related in that they both develop as a result of venous insufficiency, but sometimes varicose veins are the actual cause of the thread veins. Veins have a sort of ‘one-way’ system, with valves controlling blood flow and keeping it going in the right direction. Sometimes when we’re standing or upright for a period of time, blood can try and go against gravity and flow the wrong way through the vein, collecting/pooling in one area. This is what causes the swelling, bulging appearance of varicose veins. This swelling can then in turn put pressure on the smaller surrounding capillaries, causing the appearance of thread veins.

A Sedentary Lifestyle

Sitting around doing nothing also does little for the appearance of your legs. Particularly, crossing your legs whilst sitting down constricts circulation, making it more likely for blood to pool or gather and veins to swell.

Leg Injuries

Certain injuries can affect the veins, such as fractures in the leg. Not only can fractures damage circulation, but they can also leave you much less mobile than you would normally be, and as mentioned above, being active is key to preventing thread veins.


Jobs that require you to be on your feet for an extended period of time can result in blood circulation in the legs slowing down, and might lead to thread veins. Examples of these types of jobs include nursing, retail, hairdressing and waitressing.

Prolonged Sun Exposure

A lot of time spent in the sun has a tendency to cause thread veins, particularly in the face. Sunbathing and sunburn can trigger them, especially if you are fair skinned.


If you are significantly overweight or obese you have a much higher chance of developing thread veins. This is because the extra weight you’re carrying puts pressure on the vein walls and eventually weakens them, interfering with valves and blood flow.


Overdoing the alcohol could also cause thread veins, especially on the face. Alcohol causes blood vessels to dilate, and prolonged drinking can weaken the collagen in your skin, so the veins stay open. This results in increased blood flow to the face, and the possibility of thread veins developing, which explains the stereotypical facial redness associated with chronic alcoholism. Maybe another glass of wine wasn’t such a good idea after all!

Abdominal Tumours or Liver Disease

These kinds of severe medical conditions can obstruct regular blood flow to and from the heart, so any interruption like this can weaken the veins, and the blockage might result in the appearance of thread veins. Tumours in particular have a nasty habit of growing their own blood vessels to supply nutrients necessary to their growth. This process, called angiogenesis (simply meaning to generate vasculature), places pressure on the existing network of blood vessels, obstructing circulation and often contributing to thread vein formation.


Although chemotherapy and radiotherapy are considered to be very effective treatments of cancer, they are in fact quite damaging to the whole of the body. They are used to effectively deliberately poison the body, in the hopes that any tumours will be destroyed in the process. As the body is under a lot of strain during these procedures, veins and capillaries can often become weakened and damaged as a result and therefore thread veins might develop.

It’s difficult to pinpoint what exactly causes thread veins in certain individuals, as it could be a result of one or more of these factors mentioned above.

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