In current practice, options for venous and lymphatic malformations remain limited. Recently an oral medication, sirolimus, has been found to benefit patients when taken once or twice a day for several months. Unfortunately there are many side effects associated with this medication, some of which can be severe including, neutropenia, oral ulcerations, and lab abnormalities. The purpose of this study is to determine if once weekly dosed sirolimus will be effective for the treatment of venous and lymphatic malformations. Additionally, the study will evaluate patient satisfaction and identify adverse effects. Participants will be on the medication for 6 months with an option to continue after this time period.