Does people have pain after sclerotherapy?

A little. Sclerotherapy works by causing inflammation. As a result, you will probably have some discomfort afterwards. You can get a sort itchy, stingy feeling for about 20 minutes afterwards and then a tender, bruised feeling for a couple of days. None of this is likely to keep you from doing anything but Ibuprofen helps. Wearing compression stockings afterwards usually helps too.
Sometimes. Patients can experience some discomfort after sclerotherapy which may be due to inflammation of the treated vein, also known as phlebitis. Generally, treatment of phlebitis is very successful.
Some. Sclerotherapy is the injecting of a solution into veins to dissolve them. It is a series of tiny needle injections. It has been my experience that women tolerate this much better than men and women who have delivered babies tolerate it better then women who have not. The needles that are used are very small. The experience of the injector probably has more to do with the pain than anything.
Typically not much. Most patients do not have significant pain after sclerotherapy. In fact, it is uncommon to even need an ibuprofen. Some patients do complain of some achiness. This is generally improved with walking and wearing the compression stockings. I'd always want my patients to call me if they had significant pain after sclerotherapy.