While the exact causes of thread veins are still unknown, various factors that can trigger their appearance have been identified:
• Hormones. Some hormones, such as the female hormone oestrogen, increase the likelihood of developing thread veins as they can result in increased blood vessel formation. Women taking birth control or hormone replacement treatments are at an increased risk of developing thread veins.
• Pregnancy. A pregnant woman experiences increased hormone levels, and the increased weight can put pressure on the blood vessels in the legs, causing them to remain dilated.
• Obesity. Being overweight can put the same pressure on the circulatory system as pregnancy and increase the likelihood of thread veins appearing.
• Family. If members of your family have suffered from thread veins, you are more likely to do so, too.
• Temperature. Exposing your skin to heat causes the vessels to dilate, and excessive exposure can cause them to remain dilated. Sunburn, exposure to sunlight, saunas or even prolonged hot baths are all examples of factors that can trigger thread veins.
• Alcohol. Alcoholic drinks again increase the flow of blood to the face, causing vessels to dilate. Continuous drinking can cause these vessels to remain dilated and become visible on the surface of the skin.
• Lifestyle. Prolonged periods of sitting or standing can cause thread veins to appear on the lower limbs.