Naruto: What disease did Itachi Uchiha have? Real-life analogs to his symptoms, explored

While Naruto mangaka Masashi Kishimoto is one of the industry's best when it comes to storytelling, there is one thing that he has kept a secret from fans—Itachi's illness. From the moment it was revealed that Itachi was sick while fighting Sasuke, fans have been trying to figure out what illness the Mangekyo Sharingan user had contracted.

After Itachi massacred the Uchiha clan, Sasuke wanted to avenge his clan. Hence, he trained his entire life, hoping to defeat his older brother. However, finally, when he managed to defeat him, he learned from Tobi that Itachi had orchestrated his own demise.

Seemingly, Itachi had a terminal illness and was set to pass away soon. Hence, he made sure that he died at the hands of his younger brother Sasuke, allowing him to complete his revenge.

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Naruto: What illness did Itachi have?

Itachi Uchiha as seen in Naruto Shippuden (Image via Studio Pierrot)

It was revealed back in Naruto chapter 401 that Itachi Uchiha had a fatal illness. However, till now, neither the series nor the manga creator Masashi Kishimoto has revealed what disease Itachi had contracted. While there is a theory of what it could be in terms of the Naruto universe, it does well to take a look at the real-life analogy of his illness.

Over a decade ago, a theory appeared online, according to which, Itachi Uchiha seemingly could have contracted Microscopic Polyangiitis. It is a rare form of systemic vasculitis, which is an auto-immune disorder. The auto-immune disorder is a condition where a person's immune system mistakenly damages healthy cells in the body.

Itachi Uchiha as seen in Naruto Shippuden (Image via Studio Pierrot)

As for Microscopic Polyangiitis, it can be characterized by antineutrophil cytoplasmic antibodies attacking the small vessels, causing them to bleed as they become damaged and inflamed. Given how crucial the vessels are, it could have fatal consequences throughout different organ systems.

One of Itachi's most notable symptoms was his coughing up blood from his lungs. Given that Microscopic Polyangiitis is followed by shortness of breath and coughing, his symptoms happened to fit right into the disease's symptoms.

Itachi Uchiha as seen in Naruto Shippuden (Image via Studio Pierrot)

Additionally, Itachi could be observed having chest pains throughout the series, and chest pains are also one of the symptoms of the disease. Lastly, Itachi was known to be nearly blind while fighting Sasuke, although the anime explained that his blindness was due to his usage of Mangekyo Sharingan. However, that could also have a real-world explanation.

It is widely known that the usage of Mangekyo Sharingan and its jutsu left a huge toll on the user's body. Hence, such usage may have increased the impact of his disease. As for his bloodshot eyes, while fans are bound to assume that they were that way due to Mangekyo Sharingan, retinal hemorrhage and scleritis are also symptoms of Microscopic Polyangiitis.

Therefore, while the disease that plagued Itachi cannot be confirmed, the auto-immune disorder could be assumed to be what he had contracted.

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What could be Itachi's disease in Naruto universe?

Naruto and Sasuke as seen in Sasuke Retsuden manga (Image via Shueisha)

While there is no way to confirm it, Itachi Uchiha could have contracted a chakra illness. In the Sasuke Retsuden storyline, it was revealed that Naruto Uzumaki had a chakra illness. In his case, it was due to being exposed to a tailed beast's chakra for a prolonged time.

Similarly, Itachi could have contracted a chakra illness due to his prolonged usage of Mangekyo Sharingan. Itachi's Sharingan evolved into Mangekyo Sharingan when he was just 12 years old. Considering that he died at the age of 21 meant that he had been using his eyes for nearly a decade. Such usage may have likely severed his chakra paths, causing him to become ill.

This may lead one to ask why the other Mangekto Sharingan users did not contract the same illness. However, unlike Itachi, most Uchiha did not unlock their Mangekyo Sharingan at just 12 years of age, meaning that they had less time with it. As for Sasuke, he was able to instantly obtain Eternal Mangekyo Sharingan, avoiding the illness and its symptoms completely.