In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Answering your question, Dar Al-Ifta Al-Misriyyah, states:
A Muslim can use his zakah money to help the poor and the needy patients who suffer from chronic diseases. This is permissible provided that the patients are incapable of covering the cost of their treatment.
The poor and the needy fall under the categories of zakah recipients. God the Almighty says:
“Zakah expenditures are only for the poor and for the needy and for those employed to collect [zakah] and for bringing hearts together [for Islam] and for freeing captives [or slaves] and for those in debt and for the cause of Allah and for the [stranded] traveler—an obligation [imposed] by Allah. And Allah is Knowing and Wise.” (At-tawbah 9:60)
The poor — and likewise the needy — are among those whose income does not cover all or some of their basic needs such as food and drink, lodgings, clothing and treatment.
Almighty Allah knows best.