What is a collapsed vein? what are the causes, symptoms and treatment?

A collapsed vein is pretty much what is says on the tin. It is a vein (a vessel which carries blood) which has lost the tension in it's walls and has collapsed- (or if you imagine veins as tunnels- a cave in). In itself it is not harmful at all as there are always other veins to pick up the slack from the collapsed vein.
Some of the signs and symptoms of a common collapsed vein are:

   - Striking pain following tissue damage.
    - Skin discoloration.
    - Feeling cold ends caused by obstructed blood flow.
    - Itching.
If the collapse is just a temporary one, then there isn’t any specific treatment meant for that; just that one shouldn’t inject the same site again and again! And one can see the pain and swelling settling down with time.

If the vein collapse is permanent one, then the vein wouldn’t come back to its original form back. New blood vessels will form in place of that.