How long should you leave between laser treatment for facial thread veins?

About 3 to 4 weeks is a good interval to schedule facial vein treatments with the pulsed dye laser. Raffy Karamanoukian MD FACS

The skin of the face has a rich vascular network and recommendation to retreat facial thread veins with laser is every 4-6 weeks. Multiple session (sometimes 4-6) are needed to completely obliterate facial thread veins. 

3 to 4 weeks between laser treatments of the same veins is the usual recommended time interval. Time to respond to treatment needs to be allowed.

I suppose that you will get different answers from different laser surgeons, but if I am retreating the same area, then I usually wait four weeks. If another area is being treated then two weeks is fine.