"hi took 15mg phentermine at 9am on thursday. Have a migraine now. Is it ok to take 100mg sumatriptan now? "

Neurotransmitter pro. The issue of migraines is neurotransmitter imbalance. All other meds taken for migraines are only a prelude to another migraine, rebalancing the neurotransmitters can get rid of migraines permanently. Visit www.Neurosciecncemyths.Com for ionfomon migrianes and the program and to find a doctor to help you.
DrugDrugInteractions. Always tell your prescribing doctor(s) & dispensing pharmacist everything you're taking, whether prescription or otherwise, so that they can look for interactions prior to giving you a new medication. Short of that, there are many drug-drug interaction checkers available online. http://www.drugs.com/interactions-check.php?drug_list=1851-0, 2136-0 did not find any issues between your two medications.