Cruise ships do not put laxatives in food as that would cause legal action and bad press.
Some people may get sick from being on a cruise ship or from eating foods that may have been bad but it's rare for the food to cause food poisoning on a cruise ship.
Some people also become sick to their stomach from the cruise ship itself being on the water and they may think it's from the food they've eaten.
Organisms such as salmonella, shigella and E. coli have caused outbreaks of diarrhea on ships, and fall into the grab-bag category of "traveler's diarrhea."
In a recent cluster of gastrointestinal illnesses on a cruise ship sailing from Tenerife to the U.S., salmonella was identified as the likely culprit.
In the U.S., the risk of getting norovirus each year is about 1 in 15; a cruise passenger has about a 1 in 5,500 risk of getting laboratory-confirmed norovirus during a shipboard outbreak.
Food poisoning is common on cruise ships because of the close proximity and buffet-style dining on cruise ships are sometimes a perfect recipe for foodborne illness from both bacterial and viral pathogens to spread much more quickly than we typically see at home.