 [ Symptoms ] how long does it take methergine to work for a headache [ Disease ] methergine methylergonovine is an ergotamine type of medication it is on the market as a treatment for uterine bleeding that is the fda approved use similar medications were used to treat headaches in the past it should work for migraine it is a very strong blood vessel constrictor and has a number of serious side effects some of the side effects caused by long term use could be permanent we do not use this medication in our clinic so i am not sure how long it should take to work