Generally speaking, it is not recommended. Tell your mother her pain will be much easier to manage if she takes her medicine regularly, even if the pain feels mild or she doesn’t feel it at all. If she waits until the pain is severe, she may feel the dosage is not enough, which can accidentally lead to overdosing. If your mother still does not want to take her medication as prescribed, talk with her doctor and see if there is a non-drug alternative to manage her chronic pain.