Raw Milk Is Being Legalized in More States. Is It Safe?

Why is raw milk dangerous?

Raw milk, along with other raw dairy products like unpasteurized ice creams, yogurts and cheeses, can harbor bacteria that cause common food-borne illnesses — such as salmonella, listeria, campylobacter and E. coli. Germs may linger on a cow’s udders or in the dirt around them, or on the hands of people who milk them, which can then contaminate the milk, said Dr. Yvonne Maldonado, a professor of pediatrics, infectious diseases and epidemiology at Stanford Medicine.

Without pasteurization, which involves heating milk to kill harmful microbes, “it’s kind of like if you don’t wash your hands and you just lick them” instead, she said.

The risk of bacteria being present in raw milk remains even when dairy facilities appear to take precautions, Dr. Martin said. Many people say, “‘Oh, this is my neighborhood farm, I’ve spent time there, the animals are super clean, I would eat in that parlor,’” she said. “The reality of the situation is, that doesn’t matter.”

If bacteria are present, even a small amount of raw milk can make you sick. The symptoms typically include nausea, vomiting, stomach pain, fever, headache and body aches.

Depending on the pathogen, most healthy people recover within a few days or weeks, Dr. D’Amico said, but as with many food-borne illnesses, the symptoms can be severe and even life-threatening, especially if you’re in a higher risk group.

People can get so dehydrated from severe vomiting and diarrhea that in rare cases, their kidneys fail, said Beth Czerwony, a registered dietitian at the Cleveland Clinic. If raw milk is contaminated with campylobacter bacteria, there is a small risk — about one in 1,000, Dr. D’Amico said — that a person who becomes infected with it can develop Guillain-Barré syndrome. This can cause muscle weakness and sometimes paralysis, according to the C.D.C., although most people recover fully.

“There are people who say, ‘I’ve been drinking raw milk my whole life,’” Dr. Maldonado said. “Well, yeah, you can also drive around without a seatbelt or ride your motorcycle without a helmet.” But eventually, she said, that behavior can catch up with you.