Very ill vs Very sick

Both phrases are correct, but "very ill" sounds more formal and serious, while "very sick" is more casual and common in everyday speech. [1, 2, 3]

Using "Very Ill"

Formal tone: Often used by news reports, doctors, or in writing.
Serious health: Usually describes a severe, major, or long-lasting disease.
Example: "He is very ill in the hospital with pneumonia." [1, 2, 3, 4, 5]

Using "Very Sick"

Casual tone: Used most of the time when talking with friends and family.
General or short-term use: Can mean a bad cold, a stomach bug, or feeling like you want to throw up (nauseous).
Example: "The bad food made her very sick." [1, 2, 3, 4]