Itachi Uchiha is one of the strongest and also cult-acclaimed characters within the Naruto universe. Itachi’s story arc is one of the darkest and most complex in all anime, let alone the Naruto universe.
Itachi was a shinobi who suffered in silence, after massacring his clan as a last resort of hope, leaving Sasuke alive to avenge the clan and rebuild it, Itachi never let on what his true intentions were to anyone.

Beyond the massacre of his own clan, Itachi had a disease that was potentially deadly and was also something he never mentioned to anyone. In this guide we are going to explain Itachi’s disease so you can learn more about his elusive character.
Read on to find out.
Did Itachi Have A Disease?
Well, this isn’t really stated clearly at all, neither in the manga nor the anime. The disease isn’t mentioned in either really until Sasuke’s battle with Itachi where more of Itachi’s story is exposed by Tobi.
In the manga, and thus in the anime, when Tobi/Obito is telling Sasuke the truth about Itachi, he tells Sasuke that Itachi could have killed him at any point, that he constructed the whole battle and knew what would happen.
Tobi tells Sasuke that Itachi had an ‘disease’ that he took medicine for to prolong his life until Sasuke was of age to kill him.
Some fans really get picky about this specific term; many fans think that the translation from the Japanese is too direct and what they are in fact referring to is Itachi succumbing to the same issues of the Sharingan that Madara, and eventually Sasuke, did.
This could make sense as when Itachi does die, he has overused his Sharingan abilities to the limit.
However, the idea that Itachi had this illness the whole time and took pills in order so that Sasuke could ‘kill’ him is certainly a great prop for the plot as a whole and perhaps makes the most sense along with the other things we know about Sasuke and Itachi.
Didn’t Sasuke Kill Itachi?
Well, this is also up for debate. It’s clear in both the manga and the anime that Itachi is seriously tired before he dies, he coughs up blood and blood comes from his nose at many points but he seems to push through.
Itachi places Sasuke under a genjutsu that convinces him that Itachi is trying to steal his eyes, and actually makes Sasuke see this happen.
When in reality, Itachi walks towards him and instead of going for his eyes he touches his forehead like they did when they were children. Itachi then collapses and dies.
There is much debate among fans, if Sasuke had simply worn him out and his chakra reserves had been used up, if Sasuke had actually hit him with a fatal blow, or if Itachi has succumbed to the ‘disease’ that Tobi describes. There’s no clear answer to this question.
Our opinion is that Sasuke did not kill Itachi, while Sasuke is very powerful, it’s pretty debatable that Sasuke would have killed Itachi himself.
Itachi’s Sussano is basically invincible with the Sword of Totsuka and the Yata Mirror, as said by Zetsu, and Sasuke hadn’t even developed his Mangekyou Sharingan yet.
Plus, Itachi helps Sasuke out in many ways that suggest he wasn’t going to kill Sasuke. For example, he seals Orochimaru in the Sword of Totsuka, and also gets rid of Sasuke’s Curse Mark.

What Disease Could Itachi Have Had?
It’s hard to say. While some fans have diagnosed him like a human and suggested he had some natural issue such as a heart problem or cancer, this is merely speculation.
Other fans speculate that he had some form of chakra disease. Illness often seems to be the downfall of specifically strong characters in the manga and anime.
It seem that when Hagoromo Otsutsuki split the chakra beasts up he seems to have succumb to some sort of chakra exertion illness, although some fans would argue this is just exhausting his chakra reserves, but other fans suggest as an Otsutsuki this seems illogical.
In the very recent Naruto Retsuden novels, which are officially classed as canon, it seems that Naruto himself seems to be suffering from his own chakra-based disease. Could this be where the writers choose to disclose the actual illness Itachi had? We will have to find out.
Final Thoughts
So, unfortunately there isn’t much we can reveal about Itachi’s illness that isn’t mere speculation. We feel we have compiled all the credible information surrounding Itachi’s illness that makes some sense.
In our opinion, it seems that when Itachi died something definitely happened that wasn’t as cut and dry as ‘Sasuke killed him’. The fact that Kishimoto specifically used the word ‘disease’ (or some variation of that in Japanese) does make us think this isn’t merely chakra exhaustion.
We think Itachi does have a disease for sure, but beyond this simple fact there isn’t much else to mention that isn’t speculation.
Kishimoto seems to kill many of the overpowered characters off this way, either by chakra exhaustion or just omission, Hashirama being a good example and someone who many fans think also could have died from the same chakra disease.
So, maybe there is something to the idea, we just have to wait if it gets explained in Boruto or in auxiliary Naruto literature.