What causes varicose veins?

Varicose veins raise a "why me?" question, and the source below answers it in one sentence.

What the vein itself is doing

According to www.nhlbi.nih.gov, "Varicose veins are a common condition caused by weak or damaged vein walls and valves."

Read that as cause and effect: weak or damaged walls and valves are the cause the source names, and varicose veins are the result.

Related conditions to tell apart

Varicose veins share a neighborhood with other vein problems. The overview of venous disease lays out the family. The guide to varicose veins covers the condition itself, and the spider veins guide covers the smaller cousins. The MedlinePlus page on varicose and spider veins puts both side by side.

The question to ask before agreeing to treatment

A cause tells you what to ask next. Ask the clinician whether your veins show weak walls, damaged valves or something else, and how they know. A treatment plan should follow from that answer, not arrive before it.