If you are experiencing heartburn from Prometrium, it is recommended to first assess if the medication is truly causing the issue. You can try taking the medication at a different time of day to see if the heartburn persists or shifts. If this is not possible, you can consider taking a 10-day break from the medication and then trying it again to see if the side effects subside. If it is determined that Prometrium is indeed causing the heartburn, you have two options: either consult with a pharmacist or doctor to switch to a different progestin, or consider adding a medication to help reduce the heartburn. However, it is generally preferred to avoid giving medications to counteract the side effects of another.