How dairy farmers ensure milk is antibiotic-free

Sometimes we get asked the question, “Are antibiotics present in milk?” Any milk that you buy in a store is free of antibiotics and is tested many times before it reaches your fridge to make sure it’s healthy and safe to drink. Read on to find out more:

Are There Antibiotics in Milk? 

By Hannah Woods | Oregon State University, Dietetic Intern

Do we need to worry about antibiotics in our milk? Can we trust that milk sold in grocery stores is safe? Let’s take a look at the guidelines and regulations that farmers, transporters, and processors follow to make sure that milk stays antibiotic-free from farm to shelf!  

Why would a cow be given antibiotics?  

Farmers are required by the FDA to use disease prevention strategies to ensure that cows stay healthy and to treat them without antibiotics when possible. Unfortunately, sometimes cows get infections that cannot be treated without antibiotic medicine, much like humans. If that happens, a farmer and a veterinarian will work together to make sure that antibiotics are completely necessary for the cow to get better.

If antibiotics are prescribed, the cow’s milk will be separated from the rest of the herd’s milk. While the cow is being treated- and for a little while afterwards- all of her milk is immediately thrown out. Once the cow’s milk has tested negative for antibiotics, her milk can once again be collected and sold.  

Check out this resource to see the steps farmers take to make sure your milk is safe to drink and free of antibiotics.

Is organic milk less likely to have antibiotics? 

When it comes to antibiotics, the main difference between organic milk and conventional milk is that a cow treated with antibiotics is permanently removed from the organic milking herd. That cow can no longer be considered “organic.” However, if she is healthy enough, the cow can return to a conventional dairy farm once her milk is safe. 

How do they make sure that there are no antibiotics in milk? 

The FDA rigorously tests to make sure that there are no antibiotics in milk, down to the parts per billion.  

Milk is tested at several stages of collection and processing, including:  

  • When milk is collected from the farm, it is tested for antibiotics before being stored in a bulk milk tanker.  
  • Some tankers gather milk from multiple farms. If it is making multiple stops, the milk will be tested at every farm. 
  • Once the driver arrives at the processing plant, the milk in the tanker is tested again before it is unloaded. 

If antibiotics are found at any stage of this process, the entire batch is discarded. The samples from individual farms are then tested again to determine who provided contaminated milk.  

Farmers are very motivated to make sure that no antibiotics will be found in their milk – the farmer responsible will have to pay for the whole load of milk, which can cost over $10,000. Not only that, but they may even lose their license to sell milk. In 1996, 0.104% of 3.3 million bulk milk tankers tested positive for antibiotics. In 2021, that number dropped to 0.008% of 3.8 million bulk milk tankers. 

So is the milk I buy at the grocery store safe?  

Yes! Farmers use strategies to avoid using antibiotics as much as possible, and make sure any potentially contaminated milk is thrown out. Effective tests are done on milk and dairy products through every step of the process – from the farm to your home.  


“Antibiotic Stewardship: Beef and Dairy Cattle.” U.S. Food & Drug Administration.  

“Milk and Antibiotics: Is Your Milk Safe?” Got Milk?

“Milk and Antibiotics: Making Sure Your Milk Is Safe.” US Dairy. 06 Sept. 2017.  

“Milk & Dairy Beef Drug Residue Prevention Reference Manual 2022-2023.” Farmers Assuring Responsible Management. 2022. Accessed 12 Jan. 2023. 

Rossi, R. et al. “Multiclass Methods for the Analysis of Antibiotic Residues in Milk by Liquid Chromatography Coupled to Mass Spectometry: A Review.” Food Additives & Contaminants, vol. 35, no. 2, Feb. 2018, pp. 241-257. 

Zhang, J. et al. “Simultaneous Analysis of 19 Antibiotics in Dairy Products Using Ultra-Performance Liquid Chromatography Coupled with High Resolution Time-of-Flight Mass Spectrometry.” Chinese Journal of Chromatography, vol 30, no. 10. Oct. 2012, pp. 1031-1036.,