The US Food and Drug Administration (FDA) has warned against eating raw dough, batter or cake mixture because of the risk of E. coli from flour.
The FDA updated its guidelines following an investigation into an E. coli outbreak in the US in 2016 where flour was found to be the cause.
Cooking the flour kills any bacteria that can cause infections.
The FDA says commercially made cookie dough ice-cream products are OK as manufacturers use treated flour.
In 2016, dozens of people across the US were made sick by a strain of bacteria called Shiga toxin-producing E. coli O121, that was linked to flour.
A mill in Kansas City, Missouri, was found to be the probable source of the outbreak and ten million pounds of flour were recalled.
Previously there have been warnings about eating raw dough and cake mixture due to the presence of raw eggs that can pose a risk of salmonella.
The UK Food Standards Agency advises against eating raw dough "because it may not be safe".
But Leslie Smoot, a senior adviser for the FDA, says flour alone is also a risk.
"Flour is derived from a grain that comes directly from the field and typically is not treated to kill bacteria."
Bacteria from animal waste in the field could contaminate the grain, which is then harvested and milled into flour.
E. coli O121 can cause abdominal cramps and diarrhoea (often bloody) but most people recover within a week.
In rare cases it can cause a type of kidney failure called hemolytic uremic syndrome.
Young and elderly people and those with weakened immune systems are most at risk of complications.
Tips to handle foods safely
The FDA says we should not eat or taste any raw biscuit dough, cake mix, batter, or any other raw dough or batter product that is supposed to be cooked or baked.
- They advise carefully washing hands, work surfaces and utensils thoroughly after contact with flour and raw dough products
- When baking with children watch out for flour spreading easily
- Do not give play dough made with raw flour to children
- In the US, restaurants and retailers have been warned not to serve raw dough to customers or provide raw dough for children to play with
- Keep raw foods separate from other foods while preparing them to prevent any contamination that may be present from spreading
- They recommend following package directions for cooking products containing flour at proper temperatures and for specified times
- Follow label directions to chill products containing raw dough promptly after purchase until you bake them
- The Food Standards Agency agrees "it is advisable to follow manufacturers' cooking instructions when using food ingredients. Cooking food at the right temperature will ensure any harmful bacteria are killed."