What Causes Spider or Thread Veins?
Usually veins are invisible and just quietly go about their work. We don't bother them and they don't bother us. However, they can expand and when they do, they start to become visible under the skin. This can be a direct result of too much sun exposure, but veins may also expand in pregnancy and might not disappear after the birth. Thread veins are more visible in later life due to skin thinning and reduction of collagen.
Prolonged exposure to the sun’s rays can be very damaging to your skin and may, in fact, exacerbate any existing problems.
Other factors that may make the veins more pronounced are too much spicy food and hot or alcoholic drinks. It may not be immediately obvious that there is a link between what you put in your body and any external problems, but they are indeed connected so it is worth remembering this.