@spencersok Spitting up blood is most likely not due to coughing too hard. It is one of the symptoms of MAC. Some people with MAC never cough up blood, but others do. If you also have bronchiectasis, coughing is likely the result of that. Those living with bronchiectasis, which has no cure, are very susceptible to being infected by MAC. So for some, these two go hand in hand. I have both. I coughed up huge amount of blood a number of years back and was diagnosed with bronchiectasis and MAC back then. I also coughed a lot for good many years although my coughing has subsided recently. Because I also have many allergies, for a long time my doctor and I both thought my allergies were entirely to blame for coughing. I was very frustrated with not seeing as much improvement as I expected after all kinds of treatment for allergies. Only after being diagnosed with bronchiectasis did I realize that was why treating allergies alone had not worked effectively for my coughing. However, allergy treatment still has helped with reducing my coughing over time.