A device for treating truncal and/or collateral varicose veins, such that they may be treated fully at outpatient clinics, without the need to use local anesthetic, wherein the device links the energy or power flow emitted by the laser to the effect of the sclerosant foam and, using a method which links the physio-chemical properties of the two synergistically, removes the exceptional venous endothelium, in addition to reducing both the concentration of the sclerosant substance and that of the energy released by the laser into the vein/varicose vein, such that the entire method may be carried out fully at outpatient clinics and performed in the usual work area, without the need for a strict surgical environment or local anesthetic, with the exception of the same being used at the entry point, it not being necessary to administer local anesthetic in a perivenous, tumescent and/or truncal way.