The Unified Command in Louisiana recalled all 125 commercial vessels in Breton Sound after four crew members in three vessels involved in the oil recovery operations reported feeling sick.
Medics were going boat to boat to evaluate crew members as a precaution, said Lt. Cmdr. Rob Wyman.
The four crew members, who prompted the recall, reported feeling nauseous and dizzy, and complained of headaches and chest pains, the Deepwater Horizon Incident Joint Information Center said.
The other crew members on those boats declined treatment at the dock.
"No other personnel are reporting symptoms, but we are taking this action as an extreme safeguard," said Coast Guard Chief Petty Officer Robinson Cox.
All four crew members were taken to West Jefferson Medical Center outside New Orleans.
Hospital spokeswoman Taslin Alfonzo said that in addition to the four, the medical center also received three other men who were working on the spill cleanup.
The vessels were involved in cleaning up oil that has been gushing into the Gulf of Mexico since April when an oil rig sank about 40 miles of Louisiana, gushing an estimated 5,000 barrels (210,000 gallons) of crude a day.