The exact causes of Spider Veins are unknown. In some cases, the blockage or weakness of valves in the veins, while preventing the backward flow of blood away from the heart, may hinder the normal blood circulation eventually causing weaknesses in the veins. However, in many cases the causes of these Spider Veins are different.
Heredity
Heredity is thought to be the main cause. Weak vein walls and valves seem to be inherited characteristics and may help in determining who develops Spider Veins and at what age.
Hormones
Hormones also play an important role. The hormonal changes that occur during puberty, pregnancy, and menopause, as well as taking estrogen, progesterone, and birth control pills can cause a woman to develop Spider Veins. Heredity, or being born with weak vein valves, is the greatest factor.
Pregnancy
Women who are pregnant or using birth control pills are more likely to develop Spider Veins because hormones such as estrogen can further weaken the walls of veins. Therefore, women seem to develop this problem more often than men do.
Injury or Trauma
Spider Veins may appear after injury or trauma to the vein, such as after a broken ankle, surgery, car accident, or sports injury.
Prolonged Standing and Sitting
Standing or sitting for long periods cause a great amount of pressure to develop in the leg veins. In both conditions, the calf muscles are inactive and therefore hinder normal blood circulation. This causes blood to pool in the veins, thus resulting in enlarged vein walls known as Spider Veins.
Other factors that may contribute in developing spider veins include:
- Facial spider veins are caused by rosacea
- Being immobile for long periods (for example, being confined to bed)
- Lack of exercise
- Obesity
- Chronic sun exposure can also cause Spider Veins
