Does a change in vein color from blue/purple to red indicate spider veins are shrinking/disappearing? (& treatment is working?)

When spider veins are blue or dark purple, they may be what we call 'hypertensive' spider veins.  As they are treated, they may indeed first become red or pink before they fade away. We refer to it as a cat scratch appearance. Larger blue veins, reticular veins, should simply become less dark and smaller in  size as they shrink.

After being treated with a laser, it is common for veins to change in color. You can often expect to see darkening of the veins after treatment, and then a gradual lightening. I would not be too concerned with this occurrence. However, speaking with your treatment provider about this issue could bring you some peace of mind.

Veins usually will change in color after treatment with either laser or sclerotherapy.  The color changes vary and are due to the blood in the veins clotting from the treatment.  Veins tend to darken first after treatment then lighten as the clot is absorbed by the body.  What you describe seems to be a normal variation.