A formula intolerance and a formula allergy are two very different things. Not only are they accompanied by a different set of symptoms, but the best course of action for managing them is often different as well.
We see a moderate number of intolerances at the Helpline. Allergies are rarer, but often misunderstood and arguably over diagnosed.
**Note that milk intolerances and allergies are NOT exclusive to formula fed babies – not by a long shot. Breastfed babies and their moms must contend with these things too. Whereas a formula feeding caregiver will modify baby’s milk by changing formulas, a breastfeeding mom will have to modify baby’s milk by altering her diet.
The good news!? Despite what you’ve heard, formula fed babies go on to experience FEWER allergies in later childhood than their breastfed counterparts, per the world’s largest randomized study on breast vs formula feeding. Formula feeding PROTECTS against allergies!
A FORMULA INTOLERANCE means that some component of the formula’s ingredients is not being digested properly by baby. The ingredient most likely to cause intolerance is milk protein, though soy and whey can also be poorly-tolerated.
An intolerance isn’t dangerous to baby’s health, though it can result in some serious fussiness.
Lactase is the enzyme needed to digest lactose (present milk protein), and when there’s not enough of it, undigested lactose can move to the colon where it’s then broken down by bacteria, which causes bloating and gas. That’s why the symptoms most associated with formula intolerance are gas-related.
Intolerance Symptoms: Excessive gas (“wind”), spit-up, and fussiness due to trapped air in the belly. Baby may pull his legs up, strain like he is having a bowel movement, and wriggle back and forth.
Course of Action: First, try switching to a partially hydrolyzed formula, like Enfamil Gentlease, wherein the milk protein is broken down, harder for baby’s system to detect, and easier for him to digest. Second, try a low lactose formula like Gerber Soothe or Similac Pro Sensitive. Third, try a soy-based formula like Similac Soy. Fourth, try an extensively hydrolyzed formula (milk protein is excessively broken down and very difficult to detect) like Enfamil Nutramigen or Similac Alimentum.
A FORMULA ALLERGY goes a step further and involves the immune system. Baby’s body is treating milk protein (and possibly soy protein, too) as a foreign invader there to harm her. Therefore, it’s misguided “job” is to deploy substances to “fight” which results in an allergic reaction. The symptoms of an allergy are thus much more pronounced and severe than those of an intolerance. Additionally, an allergy can be dangerous to baby’s health.
Allergy Symptoms: A rash or eczema on the skin which can be all over (not just the diaper area), diarrhea or loose stools, blood in stool, congestion (baby sounds like she has a cold), severe spit-up which is more like vomit, extreme stomach cramping, and extreme gas that is foul smelling. In super-rare cases, trouble breathing and unconsciousness can occur.
Example of milk allergy rash (diseaseslist.org/milk-allergy/)
Example of milk allergy bloody, mucous stool
Diagnostic Criteria Necessary: Formal allergy tests need to be run to confirm. Many times pediatricians will just swipe baby’s stool for blood and diagnose if blood is present, but it’s not enough. Severe reflux can result in bloody stool as well, and reflux is a totally separate diagnosis with very different treatment protocols than a formula allergy.
Course of Action: First, try using a soy-based formula, though keep in mind that about half of babies with a milk allergy are also allergic to soy. Being allergic to both is called “Milk Soy Protein Intolerance” or MSPI. If soy is out, then you’re looking at elemental formulas that only use the building blocks of proteins to construct them instead of the full proteins themselves. Examples are Neocate and Alimentum. These formulas are extremely expensive and can sometimes qualify as medical equipment and medical insurance provision/reimbursement. Due to the excessive cost, it is imperative that you rule out all other explanations and utilize an allergy test to confirm that these products are required.
We see intolerances misclassified as allergies a lot and then treated as such (with pricey formula). And we see reflux mistaken for both intolerances AND allergies. Don’t be quick to accept one diagnosis over another and be sure to request all proper testing.
Also, note that sometimes even babies with allergies are “OK” for the first four weeks or so. While their consumption is still very small things don’t seem to go haywire. We often hear, “but they’ve been fine and now!…” When the amount of formula being consumed goes up to 3-4 oz feedings, things can start to unravel. It doesn’t mean the problem isn’t real; it just means that it went undetected by baby’s body for a little while.
The most common risk factor we see for formula allergy is an immediate family history of dairy intolerance or allergy (mom, dad, or sibling). Having an older sibling who had a formula allergy seems to be the largest predictor. That doesn’t mean that if you have one baby with a formula allergy that the next are all doomed to have it too. No need to start your new baby’s life out on elemental formula, because there’s a good chance it WON’T happen. But remain aware.
This is an extremely brief synopsis of the difference between formula intolerance and allergy, what to look for, and how to begin managing. Allergies, particularly, can grow much more complicated than presented here. BUT we live in a time where we have amazing science milk available to us to safely feed those babies with even the most restricted diets!