I read your question carefully and I understand your concern. I believe you must have got the spelling wrong for the first drug as I don t know and can t find any info on a drug called sumatriptyline could it perhaps be Sumatriptan. If that is the case, sumatriptan is not a drug which is taken regularly only for acute migraine attack while amitriptyline is taken daily to prevent these attacks. So they are used together with different targets. They are often used together although there is the risk of interaction causing a syndrome called serotonin syndrome. As I said it is very rare but it should be kept in mind as it is a threatening condition, so the frequency of taking of sumatriptan should be kept to a minimum. I hope to have been of help.