Sirolimus (also known as rapamycin) is an inhibitor of the mammalian target of rapamycin (mTOR). In recent studies, sirolimus was shown to be effective in patients with complex vascular anomalies, including KHE. Our multicenter, retrospective study demonstrated that oral sirolimus is an effective and safe option for the treatment of progressive KHE. Additionally, our data emphasized that the KHE treatment regimen should be tailored to individual patients and guided by specific clinical circumstances. In cases of severe Kasabach-Merritt phenomenon (KMP), sirolimus in combination with the short-term administration of prednisolone is recommended for controlling life-threatening conditions.