Is your reaction really lactose intolerance?

May 7, 2018 Tawnya Dorn, RD, CDE



Key takeaways:

  • There is a difference between lactose intolerance and casein allergy or sensitivity.
  • Some people can still consume limited dairy with lactose intolerance, but not with casein allergy.
  • Providence Registered Dietician Tawnya Dorn says you can still get enough calcium in your diet without dairy.

You just had a wonderful afternoon outing and now your stomach is upset, or you're feeling congested. Was the ice cream to blame? You might assume that you, like 30 million to 50 million other Americans, are lactose intolerant. But are you really? That depends on your specific symptoms.

"Lactose sensitivities are well known, but people may not be as familiar with casein allergies or a sensitivity to casein, which can also be experienced when eating or drinking dairy products," says Tawnya Dorn, RD, CDE, a registered dietitian and certified diabetes educator at Queen of the Valley Medical Center, in Napa, California. "They share some similarities in how they affect your body, but there are also some important distinctions between them."

Lactose vs. casein

Lactose is a natural sugar found in products made with milk. Casein is a protein in milk.

Lactose intolerance

If you are lactose intolerant, it means your small intestine can't properly digest lactose after eating or drinking a dairy product. That's because your body doesn't produce enough lactase, the enzyme responsible for lactose absorption. This can be a genetic condition, or it can be caused by a gastrointestinal health issue. 

Some people can have a small amount of dairy and not experience any problems, while others cannot handle any dairy. There are several symptoms indicative of lactose intolerance, and the severity of each can vary depending on how much milk you consume and your tolerance level. 

Common lactose intolerance symptoms include: 

  • Gas
  • Bloating
  • Diarrhea
  • Abdominal pain
  • Nausea
  • Vomiting

Casein allergy or sensitivity

Issues with casein differ from lactose intolerance. If your body can't handle casein, that can be considered a milk allergy, and consumption of casein triggers an allergic reaction, with symptoms including:

  • A skin rash or hives
  • Swollen lips, mouth, or tongue 
  • Runny nose and watery, itchy eyes

It may also cause symptoms that come with lactose intolerance, like bloating and stomach pain. In severe cases, a casein allergy can cause anaphylaxis, which can be a fast-moving, life-threatening allergic reaction if not treated immediately. 

Milk allergies such as a casein allergy generally are diagnosed early in life and don't suddenly appear in adulthood. While lactose intolerant people may be able to consume dairy in limited quantities, those with a casein allergy should avoid milk and milk products altogether. 

Dietary notes

If you can't consume dairy because you are lactose intolerant, there are still plenty of dairy-free versions of common foods, such as milk alternatives or lactose-free yogurt. Some cheeses, such as cheddar, are naturally low in lactose. If you have a casein allergy, it's a little trickier, as many packaged foods — ranging from salad dressings to breads to cereals — can contain milk solids, which can include casein. It's best to talk with your health care professional about the proper diet for a casein allergy.

Dorn says you shouldn't necessarily worry about a milk intolerance or allergy getting in the way of your daily calcium intake. "It is important for bone health to get enough calcium, and a diet of healthy, whole foods can help you meet your calcium goals without any dairy at all," Dorn says. "There are plenty of foods out there, including dark leafy green vegetables, white beans, black-eyed peas, sardines, almonds, and tofu that are good sources of calcium and many other beneficial nutrients."


Find a doctor

Are you concerned about a potential food allergy? It is important to discuss food sensitivities and reactions with your doctor or a registered dietitian. Your doctor or RD will work with you to identify any allergies and trigger foods and recommend a diet that is right for you. You can find a Providence physician using our provider directory. Through Providence Express Care Virtual, you can also access a full range of healthcare services. 

Providence in your inbox

Subscribe to our newsletter to get more educational and inspirational stories from the expert caregivers at Providence.


This information is not intended as a substitute for professional medical care. Always follow your health care professional's instructions.


Previous Article
Is your toddler constipated? Here’s how to find sweet relief.
Is your toddler constipated? Here’s how to find sweet relief.

If you notice your child’s normal bathroom behavior is a little off schedule, don’t panic. Ordinary constip...

Next Article
Your daily choices can lessen — or increase — your heart risk
Your daily choices can lessen — or increase — your heart risk

You might not realize how your daily decisions have ramifications that can reach all the way to the vessels...