Spider Vein Treatment - Risks

Laser and radiofrequency treatments harbor the risk of venous perforation due to heat development which can lead to further instances of bleeding and burns to the skin and tissue.8

In very rare cases, the direct closure of the veins fails, meaning that the procedure must be repeated. Actual long-term patient experiences are not yet at available at this time.⁶

For varicose vein operations, surrounding arteries may be injured which can lead to bleeding or secondary bleeding. Damage to neighboring lymphatic vessels can result in swelling.
In both treatment methods, nerves can be damaged, which can result in temporary or ongoing feelings of numbness. Further complications include wound healing problems, infections, and scar formation; however, these are rare. Allergic reactions are rare but cannot be ruled out entirely.⁵
You doctor will gladly clarify these risks as well as your personal risk situation in a private conversation.

Sources:
¹ University of Bochum Clinic
² Ruhr University of Bochum
³ University of Mannheim Clinic
⁴ German Society for Phlebology
⁵ German Society for Vascular Surgery
⁶ German Dermatological Laser Society e.V.
⁷ Ärztemagazin (Doctors' Magazine) Austria
⁸ Focus online
⁹ Lifeofyour Legs.com