Is it permissible for a fasting person to take stomach medicine when experiencing severe pain?

The arrival of medicine to the stomach invalidates the fast. If you find the fast unbearably difficult due to pain, or you fear an increase in illness or a delay in recovery, or a knowledgeable doctor informs you that fasting is harmful in this situation, then it is permissible for you to break your fast, use the medicine, and make up for the missed fast later. However, if the pain is minor and allows for continuing the fast without fear of the illness worsening, or if the doctor informs you that fasting is not harmful, then it is not permissible to take medicine while fasting, and it must be delayed until breaking the fast.