Sirolimus is a drug that has been tried for the treatment for vascular malformations with variable success rates. It has shown to decrease the size of swelling due to malformation / abnormalities of vessels according to various studies.
How to take sirolimus
Sirolimus comes as a tablet to take by mouth. It is taken twice a day and can be taken with or without food but has to be taken at fixed times. The tablet can be taken with a glass of water and should not be crushed / split/ chewed.
After 1 week of treatment blood level of sirolimus should be checked and the dose will be adapted to reach a blood level between 10 to 15 ng/ml
The blood levels of the drug can be affected by certain medication, so precautions should be taken. Concurrent use of cyclosporine/ tacrolimus may increase the risk of calcineurin inhibitor induced haemolytic uremic syndrome. Grapefruit juice, fusidic acid, Posaconazole, voriconazole, live virus vaccines should be avoided along with sirolimus. Be sure to tell your health care provider about all medications and supplements you take.
Possible side effects of sirolimus 
Peripheral edema (20-58 %)
Hypertriglyceridemia (45-57 %), hypercholesterolemia (20-46%)
Headache (20-34 %)
Bone marrow suppression- Anaemia (23-33 %), thrombocytopenia (14-30%)
Urinary tract infection (33%)
Transaminitis (<3 %)
Exposure to unborn child to this medication could cause birth defects. J. Hammer et al., “Sirolimus is efficacious in treatment for extensive and/or complex slow-flow vascular malformations: A monocentric prospective phase II study,” Orphanet J. Rare Dis., vol. 13, no. 1, pp. 1–13, 2018, doi: 10.1186/s13023-018-0934-z.  U. S. B. Warning, “Sirolimus ( conventional ): Drug information,” pp. 1–34, 2022, [Online]. Available: https://www.uptodate.com/contents/sirolimus-conventional-drug-information?search=sirolimus&selectedTitle=1~147&usage_type=panel&display_rank=1&kp_tab=drug_general&source=panel_search_result.