What did your friend do for treatment when you cut your trip short? Did he go to the emergency room? He needs to know ahead of time what will help, and bring only medications that work for him. Most people who get severe migraines find that only one or two of the dozens of available migraine medications work for them.
I get hemiplegic migraines that paralyze the left half of my body, make it impossible to speak, cause me to vomit profusely, and without treatment they last 3-4 days. I've been hospitalized many times for it. I take an anti-seizure medication every day to control them but they still occur sometimes. When I go backpacking, this is what I bring:
a) Magnesium (chelated): I bring a whole bottle of magnesium amino acid chelate capsules. Magnesium oxide (the most common kind in vitamins) is useless because it can only be absorbed in very tiny amounts. Magnesium has neurological effects at higher doses that can help with migraines. At very high doses it can actually be used to anesthetize a person. I take 10-20 400mg capsules when I get a migraine.
b) Metoclopramide, Ondansetron, or some other prescription anti-nausea drug.
c) Vicodin, Percocet, or some other prescription analgesic/narcotic.
d) Benadryl
e) a Benzodiazepine or other prescription sedative
If your friend sees a doctor, there are dozens of prescription migraine medications he can try. The triptans (including Imitrex) are helpful for many people.If your friend doesn't want to see a doctor, and he doesn't know what will work for him, I'd suggest keeping chelated magnesium, benadryl, naproxen, and caffeine on hand. The chelated magnesium and benadryl can be safely taken in large amounts (much larger than directed on the label), but the naproxen and caffeine should be used carefully. Also, if he doesn't do this already, he should keep a record of everything he did and every food he ate in the 48 hours prior to his migraines so he can identify contributing factors and avoid them.