There isn't much in the way of over-the-counter remedies specifically for migraine, since many migraine medications must be dosed carefully to avoid hazardous side effects. You're mainly limited to pain relievers if you stick with OTC remedies.
The standards (acetaminophen, ibuprofen, aspirin) can help. If you can obtain NSAID/codeine blends over the counter where you live, they might work a little better. Sometimes an antihistamine like chlorpheniramine can help.
If you want strong stuff, you'll generally have to get a prescription for it from your doctor. And it's important to follow the prescription, as bad things can happen if you overdose. But these prescription medications can be extremely effective.