I can’t tell you how many times I hear people say they are lactose intolerant and can’t drink milk but can eat cheese and they “feel” fine only to discover that it’s not a lactose intolerance at all but a dairy sensitivity or allergy.  There are important differences and you need to know how to figure this out.  If you suspect you have an issue with dairy then READ ON to learn more about the differences between lactose intolerance, dairy allergy and dairy sensitivity.

Hint…if you have bloating, diarrhea, abdominal pain, drippy nose, congestion, eczema, joint pain, hives then you might have a reaction to dairy.

Lactose is the sugar (or carbohydrate) found in dairy products.  When we eat dairy products lactose is normally broken down by an enzyme called lactase which is produced in the lining of the small intestine.  Most infants produce lactase (which breaks down the lactose) but starting around the age of 2 lactase levels can start to decline in some people.  The older you are the more your lactase levels may decrease which is why people will say they never had trouble before but as they aged they developed problems.  An estimated 65% of people have the reduced capacity to break down lactose.  If you are missing the enzyme lactase then you will be “lactose intolerant”.   Symptoms of lactose intolerance are abdominal pain, bloating, or diarrhea usually within 30-120 minutes after eating dairy products.

A dairy allergy occurs when a person has an immune reaction to the protein in dairy: casein or whey.  Reactions can result in anaphylaxis, breathing difficulty, rashes, hives, wheezing, swelling, eczema among other symptoms and are often immediate.  Dairy allergies are very common in infants and young children.  Approximately 2 in every 100 children under the age of 4 will have a dairy issue.  This can continue on into adulthood but it has also been shown if dairy is removed from their diet completely sometimes they can resume eating dairy after about 8 years of age.

A dairy sensitivity occurs when a person is having a reaction that is usually a result of histamine being released in response to casein or whey.  Symptoms can include bloating, gas, diarrhea, abdominal pain, rashes, eczema, drippy nose, congestion, fatigue, joint pain, headaches, just to name a few.   Symptoms can occur quickly or be delayed by several days making it difficult in figuring out what is causing the issue.

Symptoms are very similar in many cases with dairy allergies, sensitivities or lactose intolerance.  So how do you tell the difference?

If you have only a lactose intolerance then all you have to do is add the supplement like lactaid when you eat dairy or use lactose free dairy products and your symptoms should be completely eliminated.  You can also do a special test called a lactose tolerance test which requires you to drink a liquid that contains lots of lactose.  Two hours later, the amount of glucose is measured in the blood stream.  If your glucose doesn’t rise then you are not digesting the lactose.

To understand the difference between testing for dairy allergy and dairy sensitivity we need to dive into what IgE and IgG mean.

IgE (immunoglobulin E) antibodies are released in response to allergens that come from food or the environment as an immune response.  They produce immediate responses and can be very severe.  All anaphylactic reactions are IgE reactions.  True dairy allergies are an IgE response.  Testing for an IgE dairy allergy involves the skin prick test (RAST testing) where a small drop of liquid containing the dairy allergen is injected under your skin and then watched for a reaction. There is now a blood test that looks at IgE reactions, too.

IgG (immunoglobulin G) antibodies are the antibodies that are released to provide long-term resistance to infections but can also be made to foods.  Their half-life is a lot longer than IgE and is around 28 days.  This is why reactions can occur within hours to days after an exposure and are called a sensitivity.  Testing for the IgG dairy sensitivity involves a blood draw and evaluating (in most tests) the amount of histamine being produced.  The more histamine produced means the sensitivity is more severe.    IgG reactions are the so-called delayed reactions and are usually not tested by allergists.  An important note is I have found regardless if it is an IgE or an IgG reaction, the symptoms can be very similar and can be immediate or delayed with the exception of IgE anaphylactic reactions.

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As long as you don’t have anaphylactic reactions, if you suspect you have an issue with dairy and think it is just lactose intolerance then switch all your dairy to lactose free products.  If you still have an issue then it is not a lactose intolerance issue but is a dairy issue.   To determine if you have a dairy issue remove it from your diet 100%.  Yes, that means no milk, sour cream, ice cream, cheese, yogurt and even butter.  Do this for 3 weeks and then reintroduce one item at a time and see how you feel when you reintroduce it.  Dairy is a bit tricky because each product has different amounts of lactose, different amounts of casein and different amounts of whey.  You might react to cheddar cheese but be ok with mozzarella.  You may also notice it is dose dependent meaning you can have a small amount of dairy but when you eat a lot of it there is a problem.   Some people may be sensitive to all forms of dairy and even cross over into other types of milk like goat or sheep. If you don’t want to do an elimination diet then get the blood testing for IgE or IgG (we offer both).   If you do a food allergy or food sensitivity test and they say it is ok to eat that product but you feel bad eating it then DON’T eat it!!  There are other pathways to react to allergens that are not easily tested so bottom line is if you suspect you have a problem with a food, eliminate it and see how you feel.

Lactose is a key filler in MANY prescription medications which always surprises me since so many people cannot break this down.  I have had several patients that required alternate medications that were lactose free to not react so if you have identified that lactose (or dairy) is a problem for you check google for the inactive ingredient list of your medication.  If it has lactose then ask your doctor for a lactose free option.  Don’t stop a medication without your physicians guidance though.

What if you remove dairy and you are still having a lot of symptoms?  Then look for another food causing them.  I am a huge believer in the power of food helping you feel better as well as making you feel worse.  Just because you never had trouble with a food in the past doesn’t mean it won’t develop in the future.  I believe this is because our gut in general is compromised with the exposure of antibiotics and toxins.  In addition, our food has really changed in so many ways that it is often unrecognizable to our GI systems which will create a cascade of symptoms.


There are so many dairy free alternatives available now.  If you have a lactose or dairy issue then find products you like as substitutes and do your best to avoid the others.  Your body will thank you!  If dairy is something you just can’t live without then consider doing allergy drops (for IgG sensitivities) or allergy shots (for IgE allergies) as these might help you be able to reintroduce foods at a later date.


To your health,