Hopefully, your doctor has given you many treatment options, so that you can manage even the most severe attacks at home (including Compazine or Phenergan anti-nausea suppositories for when you are very nauseated or vomit and Imitrex or sumatriptan injection pen for severe pain). However, many people end up in an ER, where they are usually given an injection or intravenous medications. Unfortunately, there is no standard protocol for the best way to treat an acute migraine that does not respond to oral medications. Ideally, the first step should be an infusion of magnesium, which can provide fast relief for up to 50% of patients. Some ER doctors give an injection of sumatriptan or a non-narcotic pain killer ketorolac (Toradol). Others will give a nausea drug which can also help pain such as metoclopramide (Reglan) or prochlorperazine (Compazine). An allergy medicine, diphenhydramine (Benadryl) is also a popular choice.
A study by Dr. Benjamin Friedman and his colleagues at the Albert Einstein COllege of Medicine in the Bronx compared the efficacy of intravenous Reglan combined with Benadryl and Reglan without Benadryl. This was a double-blind study, meaning that neither the doctor giving the medicine nor the patient knew what was being given. They recruited 208 patients, which is a high enough number to produce reliable results. And the results showed that Reglan without Benadryl provided as much relief as with Benadryl.
Benadryl is not a dangerous drug, but can make you drowsy, so if you can, ask the doctor not to give it to you. It is not easy to tell a doctor what to do, especially during a severe migraine attack. But if doctor is agreeable, ask for intravenous magnesium followed by either sumatriptan or ketorolac injection as well as metoclopramide for nausea.