Needing more than one injection visit is a planning question, not an urgent one. No source below gives it an urgency level, so there is time to prepare.
This page sets out what three publishers say about how many sessions to expect, then marks where their answers differ in detail. For background on the condition behind these visits, see a medical encyclopedia entry on venous insufficiency.
What each session may achieve
RadiologyInfo.org says: "Each sclerotherapy session typically results in elimination of 50 to 80 percent of the injected veins."
How many visits the sources expect
Vein Directory gives a count: "A full treatment will take three to four sessions, depending on how many spider veins you have."
Cleveland Clinic is less exact: "For either treatment, you might need multiple sessions."
Steps to take when planning
- Ask your clinic how many sessions it expects for your veins.
- Ask how far apart the visits are likely to fall.
- Read what to expect afterward in a health system's guide to sclerotherapy at home.
- Keep a short note of how your legs look after each visit to share with the clinician.
Where the sources differ
Vein Directory gives a range of three to four sessions for spider veins. Cleveland Clinic says only that you might need several. Neither source is wrong, and neither can see your legs. Your clinician is the one who can tell you which description fits. A plastic surgeons' society page on spider vein treatment is a third view, from another specialty.
Where self-care ends
You can plan, ask and keep notes alone. The number of sessions for your veins is your clinic's call. A sudden change in a leg between visits should go to a clinician right away.