Question

What causes varicose veins? Are they dangerous?

Answer 1

Varicose veins are caused by weakened valves and veins in your legs. They usually aren't serious, but they can sometimes lead to other problems.

Explanation:

Varicose veins are twisted, enlarged veins near the surface of the skin. They are most common in the legs and ankles. They usually aren't serious, but they can sometimes lead to other problems.

Varicose veins are caused by weakened valves and veins in your legs. Normally, one-way valves in your veins keep blood flowing from your legs up toward your heart. When these valves do not work as they should, blood collects in your legs, and pressure builds up. The veins become weak, large, and twisted.

Varicose veins often run in families. Aging also increases your risk.

Being overweight or pregnant or having a job where you must stand for long periods of time increases pressure on leg veins. This can lead to varicose veins.
http://www.webmd.com/skin-problems-and-treatments/tc/varicose-veins-topic-overview#1

Varicose veins are gnarled, enlarged veins. Any vein may become varicose, but the veins most commonly affected are those in your legs and feet. That's because standing and walking upright increases the pressure in the veins of your lower body.

For many people, varicose veins and spider veins — a common, mild variation of varicose veins — are simply a cosmetic concern. For other people, varicose veins can cause aching pain and discomfort. Sometimes varicose veins lead to more-serious problems.

Varicose veins may also signal a higher risk of other circulatory problems. Treatment may involve self-care measures or procedures by your doctor to close or remove veins.
http://www.mayoclinic.org/diseases-conditions/varicose-veins/home/ovc-20178078