Sclerotherapy can take anywhere from a few weeks to a few months for the vein to fully close, collapse, and slowly reabsorb into the body. You won’t know if the treatment fully worked until about the 3 month mark. Because this is a gradual process, you should start to at least see minor differences within the first few weeks. In more severe cases, you may need multiple sclerotherapy injections. Fortunately, foam sclerotherapy injections are much more likely to provide you with faster, more optimal results.