A Muslim who is in extreme pain due to an illness may be given high doses of pain medication which will make them unconscious almost all the time. In such case:
a) Can a Muslim take such high doses of pain medication that will make them lose consciousness for very long periods of time?
b) Do they need to make up salat and fasts that were missed while they were unconscious? If they die, would the family need to make up their missed salat and fasts, which were missed while they were unconscious?
(a) It is permissible if this is the only way to overcome the extreme pain.
(b) They must make up the prayers based on obligatory precaution once they regain consciousness. If they die, the oldest son must make them up based on obligatory precaution if the deceased is his father. Or, he should hire someone to make them up, unless the father directed funds from his estate (i.e., in a will) for hiring someone to perform the missed prayers. Make-up of the missed prayers during unconsciousness is not required if the deceased is anyone other than the father. As for the missed fast(s), if they were unconscious throughout the whole day, then make up (qada) is not required.