One reason could be overusing his chakra. In Naruto's world, chakra is like life energy. If he overexerts himself and drains too much chakra, it can cause internal damage, leading to coughing up blood. For example, when he was training intensively or during a tough battle where he pushed his limits.
In a Naruto coughing fanfiction, it could be a sign of a more serious illness. Maybe he was poisoned during a battle, and the coughing is the first symptom. His enemies might be trying to use this to their advantage, but Naruto, being the determined ninja he is, still tries to fight back while dealing with his coughing fits.
It could be a sign of a major turning point. If Naruto starts coughing up blood, it might signal that he's in a really dangerous situation and needs to find a way to get out of it fast. This can lead to new adventures as he searches for a cure or a way to regain his strength.
Maybe he was poisoned. There are many villains in the Naruto world who use poison. If Naruto was poisoned during a fight or an ambush, it could lead to him coughing blood as his body tries to fight off the toxins. Just like how Sasuke was once poisoned and had to be treated.
Sakura would be a likely candidate. She is a medical ninja, and she has always cared about Naruto. She would use her medical skills to diagnose his condition and try to heal him. She has healed many of her comrades before, so she would be very capable of helping Naruto.
The sudden coughing of bright red blood could be caused by a variety of reasons. These included bronchial diseases, lung diseases, cardiac diseases, general diseases, and drug factors. The specific cause of the disease needed to be confirmed through the relevant examinations and medical history collection in the hospital. The common causes of the disease included bronchiectasis, lung inflammation, lung cancer, and so on. Therefore, if there is a sudden cough of bright red blood, it is recommended to seek medical attention in time for relevant examination and treatment.
We can determine whether the coughing blood comes from the lungs by the following aspects:
1. Blood volume coughed up: The amount of blood coughed up by the lungs was usually larger, while the amount of blood coughed up by the throat was smaller.
2. The nature and color of coughing blood: If the blood and phlegm that is spat out are evenly mixed, it is mainly deep lung bleeding. If the blood was dark red, it usually meant that the lungs were coughing up blood.
3. " To determine the primary disease: There are many reasons for coughing up blood in the lungs, such as lung cancer or tumors, which may cause coughing up blood.
However, these methods of judgment were not particularly accurate. In order to determine where the blood came from, it was recommended to perform a mammoscopy and chest CT to determine the location of the tumor.
One reason could be a hidden disease or affliction that is unique to the fanfiction world he is in. It could be something that has been passed down in his family magically. Or perhaps he has been in a situation where he was exposed to a harmful magical energy source for too long. This continuous exposure could gradually damage his body and result in coughing up blood. For instance, if he was trapped near a leaking magical artifact that emits harmful rays.
Another possibility is internal injuries from a battle. Fanfiction often has intense battles that are not part of the original story. Harry could have been hit by a powerful spell during a fight that caused internal damage, which then makes him cough up blood.