What causes spider veins?
They develop when pressure rises in small veins near the surface and the vessel walls widen; family predisposition is one of the main factors.
Hormonal changes, pregnancy, long hours standing or sitting, weight, age and past injuries can raise the risk. A family history of vein problems makes it more likely.
Most of the time it is a cosmetic matter, but in some people it relates to weakness of deeper veins. An examination is therefore important to tell the difference.
How do I tell a cosmetic problem from vein disease?
Pain, heaviness, swelling, cramps, bulging varicose veins, skin darkening or sores suggest an underlying vein disease that a vascular surgeon should assess.
These signs can point to venous insufficiency. In that case treating only the surface veins may not be enough and the problem may return.
If needed, vein function is assessed with tests such as Doppler ultrasound. Sudden swelling in one leg with pain and redness may need urgent assessment; seek care without waiting.
What is sclerotherapy?
Sclerotherapy involves injecting a sclerosing agent into the target vein so that it closes and gradually fades from view.
The choice of agent and technique depends on the size of the vein and the area and is made by the doctor. Several sessions are often needed, and a bandage or compression stockings may be advised afterwards.
Risks include bruising, temporary dark marks, new fine veins, pain and, rarely, skin ulcers. Allergy, clotting disorders or a history of deep vein thrombosis affect suitability. This is generally done within vascular surgery or by an appropriately experienced doctor.
Can lasers treat leg veins?
For very fine veins, vascular-targeted lasers may be considered in selected cases; for wider veins sclerotherapy is usually more suitable.
Lasers use light absorbed by blood in the vessel to close it. Effectiveness may be lower and the risk of burns or marks higher in dark or tanned skin and with deeper veins.
See the vascular laser page for the general principle. The method is chosen by vein type and size at examination.
What should be considered after treatment?
Following the doctor's advice on compression, walking, and avoiding sun and heat supports healing.
In the first days, the doctor's instructions on hot environments, heavy exercise and long periods standing still are essential. Treatment of tanned skin is usually postponed.
If you have pain, marked swelling, shortness of breath or swelling in just one leg, seek care promptly. Home management is not advised for these.
Frequently asked questions
Are spider veins dangerous?
They are usually harmless and cosmetic, but if pain, swelling or skin changes accompany them, a vascular surgeon should assess.
Do they go away on their own?
They usually do not disappear by themselves, and some increase over time.
How many sessions are needed?
It depends on the number and size of veins; often several sessions with follow-up are needed.
Can new veins appear after treatment?
Yes, because the predisposition continues, new veins may form.
Is treatment done in pregnancy?
It is generally postponed until after birth and breastfeeding; some pregnancy-related veins may improve after delivery.
Which doctor should I see?
A vascular surgery or relevant specialist examination is appropriate first, to rule out vein disease.
Sources (5)
- American Academy of Dermatology: Leg veins: Why they appear and how dermatologists treat them
- U.S. FDA (DailyMed, NLM): ASCLERA- polidocanol injection, solution (Prescribing Information) (2025)
- Phlebology (peer-reviewed journal): European guidelines for sclerotherapy in chronic venous disorders (2014)
- Cochrane Database of Systematic Reviews (peer-reviewed journal): Treatment for telangiectasias and reticular veins (2021)
- European Journal of Vascular and Endovascular Surgery (peer-reviewed journal): Editor's Choice - European Society for Vascular Surgery (ESVS) 2022 Clinical Practice Guidelines on the Management of Chronic Venous Disease of the Lower Limbs (2022)
This content is for general information and does not replace a personal medical assessment.