Narrative:

While I was acting as captain and PF; I became extremely ill. I was incredibly nauseous. I left the flight deck to throw up in the first class lavatory. I returned to the flight deck numerous times between violent nauseous episodes and directed my first officer to assume command; declare an emergency and request an immediate return to ZZZ.

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Original NASA ASRS Text

Title: B737 CAPT ILL WITH NAUSEA AND VOMITING DIRECTS FO TO ASSUME COMMAND AND RETURN TO THE DEP ARPT.

Narrative: WHILE I WAS ACTING AS CAPT AND PF; I BECAME EXTREMELY ILL. I WAS INCREDIBLY NAUSEOUS. I LEFT THE FLT DECK TO THROW UP IN THE FIRST CLASS LAVATORY. I RETURNED TO THE FLT DECK NUMEROUS TIMES BTWN VIOLENT NAUSEOUS EPISODES AND DIRECTED MY FO TO ASSUME COMMAND; DECLARE AN EMER AND REQUEST AN IMMEDIATE RETURN TO ZZZ.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.