Joan,
I'm not a doctor, so this is just my opinion -- Yes, anyone who has problems with nausea should have access to nausea meds. It doesn't make sense to just let him suffer the nausea.
There are many, many preventives other than Elavil and Depakote. I can sympathize with his hating to take meds, but he needs to learn that Migraine is a disease, one he will have for the rest of his life. It needs to be treated.
Good luck,
Teri