Spider veins are the smallest form of varicose veins. They are smaller than 1 mm, usually blueish or reddish and are located in the skin, which is why they cannot be surgically removed.

Around 60% of the population have at least spider veins as a sign of vein disease (Bonn Vein Study, etc.).

50% of patients with spider veins already show involvement of the trunk and/or main veins, which is why a Doppler duplex sonography (ultrasound) should be carried out before sclerotherapy.

If there are larger veins preventing the spider veins, these must be put out of action before sclerotherapy in order for the treatment to be successful.

Varicose veins (varices) are more serious than is generally assumed. Even without symptoms, varicose veins should not be taken lightly. The causes of varicose veins are divided into two groups:
Firstly, primary varicosis, which is a congenital, very often inherited predisposition to vein wall weakness. Due to the overstretching and dilation of the vein walls, it leads to valves that no longer function properly. This results in a slower return flow to the heart or even a backflow of blood into the legs.
The second group includes secondary varicosis, an acquired disease that is caused by a drainage disorder in the deep veins (thrombosis, blood clots) or external space requirements (pregnancy, obesity). The drainage is instead via the superficial venous system (so-called flow reversal).

Sclerotherapy has been carried out successfully for over 50 years using the same alcohol solution. This medication is injected into the vein, irritating the vein walls and causing them to stick together. A glycerine solution can also be used as an alternative. The sclerosed veins are then converted into normal connective tissue over a period of several months.

Nowadays, depending on their size, the veins are also treated with sclerosing agents processed into foam, which also leads to good results with larger varicose veins.

Several treatments are usually necessary, as the entire spider vein areas do not disappear completely the first time and/or not enough sclerosing agent may be injected.

Wearing compression stockings supports the success of the treatment and reduces the undesirable side effects.

Laser treatment may be required as a supplement for the finest reddish spider veins.