Each stage has its treatment.
It might start by electrode therapy for small sized veins, mainly for esthetic reasons.
Larger veins might need sclerosing agents injected through the skin.
Very large veins might need surgery, whether by complete vein stripping, or by cryotherapy, or other techniques.
To prevent progression at any stage, leg stocking (bas à varices) should be worn, and staying upright without moving should be prevented.
Intimal regeneration medicines (for example Vessel Due F) seem promising.