Hello! Welcome and thank you for your question on HCM! I would explain that this could be related to tolerance developed by your body towards this medication. How frequent are your migraine attacks? In case your migraine attacks are very frequent, I would recommend starting a preventive therapy to reduce the frequency and severity of migraine attacks. I would recommend starting a calcium channel blocker (verapamil), a betablocker (propranolol) or an antidepressant (amytriptiline, etc.). Antiepileptic drugs like lamotrigine, topiramate or valproate could be effective too. You should discuss with your doctor on the above treatment options and choose the one which is more appropriate to your clinical situation (which you could tolerate better). Hope to have been of help! Greetings! Dr. Aida