Hello !. Thank you for your question! Regarding your concern I would not worry to much for that overdosed diltiazem ( for a month or longer); as you don t has experienced serious unwanted effects; but I am more disturbed by that flushing in your face: probably any adverse effect of diltiazem (it is a calcium channel blocker and as such he has the potential to induce edema and flushing). I recommend you to talk with your doctor: is it necessary to continue with diltiazem (do you have any co-morbidity that forced that choice? If no them it is better to change for another drug wit ha better security profile). Regarding your concern about life expectancy I would like to lighten your anxiety: with the current treatment of heart failure the life tends to be prolonged more than ever. If you need more exact definition please send to me a detailed medical history coupled with lab exams and other tests (like echo, etc). Hope to have been helpful. Greetings by Dr. Iliri