Thank you for asking this question!  

Unpasteurized (raw) milk can be harmful and Stop Foodborne Illness recommends avoiding raw milk and raw milk products completely whether it is bought from a store or a local farmer. Unpasteurized milk has significantly higher counts of bacteria than pasteurized milk. If left unrefrigerated (or outside), bacteria can freely replicate. While children, elderly, and immunocompromised individuals have a greater risk, healthy individuals can also become infected. Drinking raw milk could very likely cause vomiting, nausea, diarrhea, stomach pain, and stomach cramping that lasts days. In some cases of raw milk consumption, individuals have suffered from life-threatening illness and even death.  

Mari is a woman who led an active life, was a registered nurse and sought to be as healthy as possible. Read about her personal experience battling Campylobacter after consuming raw milk.

Even for healthy individuals, I personally always advise against consuming unpasteurized milk. Raw milk can carry harmful bacteria such as Campylobacter, Listeria, and E. coli. In pasteurized milk, harmful bacteria are killed off and are not a concern. However, these pathogens all pose a threat when it comes to raw milk.  

Refrigeration is a key part of keeping the food we eat safe because it prevents bacteria that may be present from increasing quickly. The US Food and Drug Administration (FDA) advises consumers not to leave food (including pasteurized and unpasteurized milk) requiring refrigeration out of the fridge for longer than 2 hrs. Additionally, food should not be left outside longer than 1 hr if the temperature is higher than 90 °F.  The longer the food is left unrefrigerated, the greater the risk becomes.  

If you have specific concerns, you should contact the farmer before consuming their milk. Otherwise, check out this article or contact me if you would like additional information or have any follow-up questions.