Ask a doc: Am I lactose intolerant, or is it an allergy?

Ask a doc: Am I lactose intolerant, or is it an allergy?

Q: I noticed that I start cramping and have to run to use the bathroom shortly after I ingest dairy. Am I allergic to milk, or am I lactose intolerant?

Dr. Kenneth Chi, a gastroenterologist at Advocate Lutheran General Hospital in Park Ridge, Ill. answers:

First, you should know what the difference between having lactose intolerance and a milk allergy.

Lactose intolerance, or dairy sensitivity, is the inability to break down milk protein well due to a decreased amount of lactase enzyme in the small bowel. Lactose intolerance and a milk allergy are similar in many ways, but when someone has an allergy to milk, their reaction is generally more severe in nature.

What are the symptoms for each condition? 

They share common symptoms such as nausea, bloating, diarrhea and abdominal cramping, but a true allergy to milk protein often includes more serious symptoms such as trouble breathing, hives and/or a rash.

In most cases, a milk allergy will first expose itself as an upset stomach, and you won’t realize the link between it and the symptom until it has happened multiple times. If you start to notice symptoms, try using a food diary to take notes about what you’re eating and how your body is reacting to it. Most of the time, the first reaction to the food is mild, and the intensity will develop the more exposure you have to it.

Can you be tested to find out if you are lactose intolerant?

One method to objectively show evidence of lactose intolerance, which can be performed at Advocate Lutheran General hospital, is a breath hydrogen test. Labelled hydrogen is measured after drinking dairy or another sugar, and if an abnormal elevation of breath hydrogen is measured, there is likely difficulty in digesting that particular sugar or protein being measured. However, most people can figure out if they are lactose intolerant by noticing a symptom pattern after eating dairy products.

What can you do to help your sensitivity or allergy? 

Once a sensitivity or allergy to milk is determined, it is usually easiest to avoid those foods in the diet. Because of this, people should remember to obtain an adequate amount of calcium and vitamin D in their diet. Lactase enzyme is commercially available as an over-the-counter pill that people can take with meals to help break down milk protein for people who are lactose intolerant. For those who have true cow-milk allergy, it may be best to avoid this type of milk and consider another form of milk (e.g. soy or almond) although people could be allergic to these types of milk, as well, so formal allergy testing would be helpful.

Have a question for a doctor? Submit it here.

Related Posts



  1. Lactose intolerance is due to the inability to breakdown lactose, a disaccharide into the monosaccharaides, glucose and galactose, through the action of the
    enzyme lactase. Therefore, lactose is a milk sugar not a milk protein

  2. i believe the introduction to this article is incorrect. Lactose intolerance is the inability to break down lactose, a milk SUGAR, not a protein. Also, I’m surprised to see no mention of replacing milk by cheeses, yogurt, etc. I believe that in these products, the enzymes that ferment the milk to cheese or yogurt have already broken down the lactose.

  3. If I go to a non-dairy diet, I expect that I will feel much better. (I have constant nasal/sinus congestion.) My question is: Let’s say a few months down the road after going off dairy, if I eat a very small amount of dairy (as a minor ingredient in some sort of prepared food), is that likely to create a temporary return to congestion, with my body reacting to even that very small amount? And if yes, will it then probably take a few weeks for my body to readjust again to being not affected by that one episode of ingesting dairy?

About the Author

Marrison Worthington
Marrison Worthington

Marrison Worthington, health enews contributor, is a public affairs and marketing manager at Advocate Christ Medical Center in Oak Lawn, Illinois. She is a graduate of Illinois State University and has several years of global corporate communications experience under her belt. Marrison loves spending her free time traveling, reading organizational development blogs, trying new cooking recipes, and playing with her golden retriever, Ari.