A method is provided for the acute treatment of migraine headaches with or without aura by injecting dihydroergotamine mesylate into a subject. The method includes storing the dihydroergotamine mesylate in an autoinjector at room temperature in a foil pouch. The method further includes removing the autoinjector from the pouch; removing a cap of the autoinjector; pushing the autoinjector down against an injection site of the subject to depress a safety guard; pressing and releasing an activation button on the autoinjector to start injection; and holding the autoinjector against the injection site for at least 10 seconds irrespective of whether a click is generated. The method further includes confirming that the injection is complete by viewing a change of color in a viewing window of the autoinjector, and lifting the autoinjector up away from the injection site and allowing the guard to drop down and lock over a needle.