Milk Allergy or Lactose Intolerance?

There are many individuals who have to avoid milk, but why do they have to? Is it because of an allergy or intolerance? Many people don’t realize that there are different causes to some of the similar symptoms, like stomach upset, that can occur after consuming milk. There is a difference between cow’s milk allergy and lactose intolerance.

Cow’s Milk Allergy

Cow’s milk allergy is an immune response to the proteins found in cow’s milk. Most often milk allergy is seen in children, in fact, by age 5 most children outgrow their milk allergy. Milk allergy is more complicated than other allergies as milk has many different proteins that an individual may have an immune response to.

Milk allergy has symptoms that can be seen with many allergies, as well as some that are more specifically seen in the gastrointestinal track. Some of the skin symptoms include eczema, hives, and swelling. With the gastrointestinal track, bloating, pain, gas, diarrhea, constipation, nausea, and vomiting can be experienced. There is also the possibility to have respiratory issues such as asthma. With allergies, symptoms are usually seen directly following exposure, but milk allergy symptoms can appear within minutes or up to 20 hours following consumption.

Milk allergy should be evaluated by an allergist. They will take into consideration patient history, blood tests, and other diagnostic tools to diagnose a milk allergy and choose an appropriate course of action. Often the individual may have to eliminate all milk and milk-containing foods from their diet. With the use of immunotherapy treatment or possible growing out of the allergy, it may be possible to try milk again. In these cases, a food challenge can be the final assessment of tolerance of milk.

Lactose Intolerance

Lactose intolerance is caused by a deficiency of the lactase enzyme. Lactase is an enzyme in the intestines that breaks lactose (the sugar found in milk) down into a form that the body can absorb. When there isn’t enough lactase in the intestine, the lactose can’t be broken down. Lactose intolerance is often seen as people age, when the production of lactase naturally decreases. Lactose intolerance is also more prevalent in certain ethnicities including Asians, Africans, Native Americans, and those of Middle Eastern descent.

Lactose intolerance symptoms are found only in the gastrointestinal track. They can include abdominal pain, diarrhea, excessive flatulence, bloating, and nausea. Symptoms can occur anywhere from minutes after eating lactose or hours following. The severity of symptoms is based upon the amount of lactase the body is producing (if any) and the amount of lactose consumed.

A gastroenterologist can perform various tests to diagnose lactose intolerance. Lactose intolerance is easier to adjust to as some lactose may still be tolerated. Some individuals need to just limit the amount of lactose consumed in one sitting or eat it with other foods. Another option is to use milk that has lactase added to breakdown the lactose prior to consuming, or by taking a lactase tablet that helps the body digest the lactose. It’s important to note that the amount of lactose varies in different foods, for example, yogurt and cheese will naturally have less lactose as some of it has been fermented during the process of making the product, so these may be better tolerated by those with lactose intolerance.

You should consult with a physician to determine whether milk allergy or lactose intolerance is the reason for symptoms following milk consumption. Specialists will be able to better help individuals know what and how much to be eating after an accurate diagnosis. Allergy drops may also help treat milk allergy.


By Sarah Aubin, Nutrition and Dietetic Student, Allergy Associates of La Crosse


Janeja JV. The health professional’s guide to food allergies and intolerances. 2013.