The US public should avoid eating romaine lettuce, warned the Centers for Disease Control and Prevention (CDC).
The warning came after 32 people were infected with the deadly E. coli O157 bacteria across 11 states.
Thirteen patients have been hospitalised with the E. coli infection, and one developed kidney failure.
The infection has been linked to romaine lettuce, although an investigation is ongoing, said the CDC.
People that have romaine lettuce in their home should not eat it, and should throw it away, it urged.
That includes all types of romaine lettuce, including whole heads of romaine, hearts of romaine, and bags or boxes of pre-cut lettuce.
Once you’ve thrown it away, wash and sanitise the drawers or shelves where it was stored.
“CDC is advising that US consumers not eat any romaine lettuce, and retailers and restaurants not serve or sell any, until we learn more about the outbreak,” said the CDC.
“Consumers who have any type of romaine lettuce in their home should not eat it and should throw it away, even if some of it was eaten and no one has gotten sick.
“Restaurants and retailers should not serve or sell any romaine lettuce, including salads and salad mixes containing romaine.
“Take action if you have symptoms of an E. coli infection. Talk to your healthcare provider.”
The symptoms of E. coli vary from person to person, added the CDC.
But, signs of infection usually include severe stomach cramps, bloody diarrhoea, and vomiting.
Some patients also develop a fever of around 38.5 degrees Celsius.
“Some infections are very mild, but others are severe or even life-threatening,” it added.
Most people that are infected with the E. coli bacteria start to feel sick after three of four days.
You should speak to a doctor if you have diarrhoea that lasts more than three days, or is accompanied by a high fever.
Finding blood in your stool, or vomiting so much that you can’t keep liquids down, should also be seen by a doctor, it said.
Between five and 10 per cent of patients develop haemolytic uremic syndrome after infection, which is a type of kidney failure.
Most people with the complication recover after a few weeks, but some may suffer permanent damage, and could even die.