Why Do I Feel Sick When I Eat Dairy?

Updated: Sep 2

There are many reasons why you may feel sick when you eat dairy.

Common symptoms of dairy intolerance include nausea, bloating, hives, headaches, sleeplessness, anxiety, acne, and joint pain.

These symptoms are usually written off as 'lactose intolerance' and lifelong dairy avoidance is recommended.

This is unfortunate for two reasons - firstly, lifelong abstinence from dairy is usually not required after the underlying cause of dairy sensitivity is found.

But the most important reason is that by labeling the cause of these symptoms as a generic 'intolerance' it leaves the true cause of dairy intolerance to remain present or to get worse.

blue background with dairy products with text overlay Why Do I Feel Sick When I Eat Dairy? Dr. Brian Lum, DC, IFMCP Functional Medicine Doctor

Causes of Dairy Intolerance

A common cause of feeling sick when you eat dairy is an underlying bacterial infection. That bacterial culprit can be Streptococcus, which is the same bacteria that causes strep throat. In this case, Streptococcus inhabits the liver and intestines.

Staphylococcus is also a common culprit in those who experience symptoms from dairy as are parasites. Both parasites and Streptococcus are relatively easy to check for using testing.

Mold is also a common cause of dairy sensitivity as well as a wide range of other symptoms.

One patient I had with dairy sensitivities was a 31-year-old woman who only notices nasal congestion or tension in her forehead the night after she has eaten some dairy.

She has other symptoms including migraines around her period, frequent waking up in the middle of the night, low energy, the feeling of blocked ears, and high levels of general anxiety.

Because her 'secondary symptoms' were written off by her primary care doctor as 'hormonal' and were not considered important, this patient thought she just had to learn to live with these symptoms.

When the patient ate dairy, elements in the dairy products were feeding her Streptococcus infection so it grew quickly.

That larger infection produced waste products which caused inflammation - making her feel sick and contributing to her long term 'secondary' symptoms.