Conversation so far:
When was Rajinikanth hospitalized?
During the principal photography of Rana on 29 April 2011 he was hospitalized.
Why was Rajinikanth in the hospital?
Rajinikanth suffered a mild foodborne illness, which led to vomiting, dehydration, and exhaustion.

Question: How long was he in the hospital?
Self-contained rewrite: How long was Rajinikanth in the hospital?