Jan 242019

The Tummy Bug and Temporary Lactose Intolerance

The Tummy Bug and Temporary Lactose Intolerance

Unfortunately, it is the time of year that illness spreads like wildfire. Through the years, I have found that few people realize that becoming ill with a bug that causes gastrointestinal (GI) symptoms, aka, the dreaded tummy bug, can cause temporary lactose intolerance. This type of lactose intolerance is usually associated with a viral illness, however, I have seen it present in other illness situations. Therefore, anytime a person has an illness that causes GI symptoms, I suggest a short break from lactose.

Lactase Production

Lactase is the enzyme that breaks one molecule of lactose into two smaller molecules. These two smaller molecules are glucose and galactose. Lactose cannot be absorbed unless it is broken down by the lactase enzyme. Because human milk is rich in lactose, lactase production is very high during infancy and early childhood. As we age this production may decrease and symptoms of lactose intolerance may develop.

The small intestines look much like hairy fingers. Lactase is made on the hairy protuberances (microvilli) of the small intestines. Anything that causes damage to these cells can cause lactose intolerance because lactase production is impaired. Believe me, these small cells are vulnerable to damage. Tummy bugs, Celiac disease, and medications are among the many things that can damage these small cells and cause lactose intolerance.

Little Bit’s Experience with Viral-Induced Lactose Intolerance

At a mere 17 months old, Little Bit had her first tummy bug. Thankfully, she was able to keep some fluids down during the worst of it, so I thought we would be in the clear. Because I know that this type of virus can damage the cells that make lactase, I left her off dairy for about 5 days. Typically, this viral-induced lactose intolerance only lasts 3-5 days. I was confident that by waiting 5 days, we would be in the clear. I let her have yogurt and within no time, she vomited. Followed by diarrhea that afternoon. The vomiting was a bit unusual, but the diarrhea was a pretty classic symptom of lactose intolerance so I suspected her GI tract had not yet recovered. Back off dairy we went for another 5 days. I again let her have yogurt. The vomiting returned. By now we had been battling these symptoms off and on for almost two weeks. My mama heart was starting to stress a little, and Hubs wanted her to see a doctor. By the time we made it in, she was ravenously eating everything in sight. Typical right?

We did not receive any solid answers at the doctor that day. Were told it was likely viral and taking a little longer than usual to run its course. I decided it was time to stop thinking like a mom and think about this situation from a clinical nutrition standpoint. My clinical intuition was telling me that this virus was doing more damage than I realized to her intestines. Perhaps even having a prolonged inflammatory immune response. It was time to treat my daughter as though she was one of my patients.


I decided to take Little Bit off of dairy for 6 weeks, to give her gut time to completely heal. I won’t lie, this was a difficult time. Little Bit LOVES her milk. I tried almond milk, but she was not fan of the taste. Because the nut juices (milk alternatives) are nutritionally inferior to regular dairy milk, I chose not the fight the battle and let it go. No milk or milk alternatives for 6 weeks.

During this time I also put her on a probiotic supplement. There is some controversy regarding how effective probiotics are in overall health, but I speak from experience when I say that they are usually beneficial when treating a sick gut.

After 6 weeks had passed symptom free, I decided to begin slow re-introduction of dairy. Just a couple of small cubes of cheddar cheese with her lunch. This went well. Over the coming days, I increased this amount. Again, all went well. Next, I added just a small spoonful of yogurt. I was going slowly and deliberately. Over the course of 7-10 days, we were tolerating cheese and yogurt beautifully. Our final re-introduction was milk. Again, small amounts at first. It too went well. I knew at this point, that the two weeks of intermittent vomiting that followed the initial illness, was very likely temporary viral-induced lactose intolerance. The symptoms were a bit unusual. I would not normally link vomiting and lactose intolerance. I would be more inclined to look for bloating, gas, and diarrhea with lactose intolerance. However, years of clinical practice has taught me to not be surprised by the unexpected.

Surprising Revelation

In the midst of no-dairy phase, another mother mentioned to me that her daughter has been through something similar. Her doctor failed to tell her that the lactose intolerance associated with viral illness is usually temporary. Therefore, FOUR years after her daughter’s tummy bug, she still had her off dairy and believed her to be lactose intolerant.

The doctor I took Little Bit to, acknowledged that viruses can cause lactose intolerance. But he too failed to mention the temporary aspect. In fact, no other healthcare professional mentioned the temporary nature of the condition to me. It was my training as a Dietitian that gave me the knowledge to know how to best manage Little Bit’s illness.

That is why I wanted to share this experience on this blog. Illness of the GI tract is just not something most of us can avoid forever. However, knowing how to help our guts along in the healing process is important. Here is to hoping nobody that reads this ever has to do a full 6 week reset!