I like to experiment on myself a lot. If I find a cheaper route than going to the doctor, I'm happy. I share it with others too. I use insulin syringes to inject the spider veins, and varicose veins, with 30% solution of NaCl, which is sodium chloride. I honestly just use the magnesium chloride you can spray on yourself. I mix 1/3 with that solution, then I put in 2/3 of water. If you don't have the spray, just dissolve sea salt and make a solution of 1/3 salt to 2/3 water. I fill up the syringes with that and be prepared for the sting. It does sting, which is normal. Docs don't use this type of solution anymore because it stings. I luckily was able to get my hands on some Lidocaine which I swiped from a doctor's office (I'm poor! ). I mix that in the solution a bit, which helps alleviate the pain.
Honestly, this is just what sclerotherapy is, but without the exorbitant price. I've had it done a few times and I just cannot afford the 3k bill to have this done every few years. I figured out how to do it myself. Make sure you only inject just a little bit into the veins, but right INTO the veins. It'll cause the spider vein to collapse in on itself. You're just injecting saline into your body, which isn't harmful. Just don't freak out when you see bruises because that's normal and they'll heal.
Obviously, if you're diabetic, don't try this on your own. Also, when you inject a vein with one of those insulin needles (which are super thin) if you see blood that comes out of your skin, that means you did good because you injected the spider vein.