Allah does not burden a person beyond what they can bear... So can we break our fast if we have a headache or a migraine? What is the general rule when it comes to breaking our fast?
The general rule is that a fast can only be broken for a very severe emergency. You have to be the judge of that...
Shaykh Yasir Qadhi explains
The general rule is that the fast can only be broken for a very severe emergency, so you have to judge best. The average headache, or the average minor irritation or nuisance must be borne with. However, if it is so severe that life becomes extremely difficult, that you are scared you're going to faint or you're not going to be able to make it to the end of the day, at this point in time ... and you know best, what is your threshold limit - people are different - at that point in time, if it's a very severe overpowering migraine and you feel that you're not going to be able to last without severe problems or repercussions, you are allowed to break the fast and then make it up afterwards.
Allah (subhanahu wa ta’aala) says in the Qur'aan [2:286]: (‘La yakallafoo-llaahu nafsan illa wus-saahaa’) . Allah does not place a burden on a person more than what he or she can bear. If you really cannot bear it, and it is unbearable - and only you know what is unbearable- then you are allowed to break the fast and then make it up a day after Ramadan.