Formula Intolerance Unveiled: Common Signs and Causes You Should Know
Formula marketing constantly reminds parents that formulas can cause digestive problems due to formula intolerance. Maybe you’ve suspected your baby is experiencing formula intolerance. Here are key things to consider.
As you have likely figured out, deciphering the root cause of digestive symptoms isn’t straightforward. It takes some real detective work.
But I’ll be honest, it isn’t as straightforward as formula marketing says it is. One thing I’ve learned working with hundreds of families, is that digestive symptoms are always contextual.
In this article, I’ll review:
What is Formula Intolerance?
Formula intolerance is a general term that describes a set of signs and symptoms. These signs and symptoms are caused by or made worse by consuming a particular formula or formulas with specific ingredients.
Formula intolerance symptoms tend to be medically mild, but bothersome to both baby and caregiver.
Importantly, formula intolerance is not an allergy. Formula intolerance does not involve the immune system while an allergy does. The confusing part is that the symptoms of an allergy overlap with those of formula intolerance. So, you may initially think that a baby has a formula intolerance when she is actually showing the first signs of an allergy.
To muddle things up more, signs of intolerance are also the same ones for other medical conditions in infancy like reflux disease. And they can also show up for a few days with a mild viral illness.
So, figuring out if certain symptoms are the cause of a formula intolerance requires looking at age and symptoms. And also, a little time to see if anything changes.
As you’ll see in the next section, mild digestive concerns may not be a sign of anything but a growing thriving baby.
What are the Signs of Formula Intolerance?
Formula intolerance signs can range from mild to severe. They may involve any part of the GI tract (mouth, esophagus, stomach, small intestine, large intestine).
Signs of a Mild Formula Intolerance
Mild signs of formula intolerance are bothersome include:
excessive crying once or twice a day
spitting up more than caregivers think is reasonable
gassiness
difficulty pooping with or without poops that are hard
Mild symptoms like these may not be because of the infant formula ingredients or brand. Infant digestive concerns can be functional, meaning that they can’t be explained by a condition or disease. Functional GI (FGID) disorders are not problems that sleep deprived parents make up. They are very real. There are even criteria to diagnosis them.
The good news is that, sometimes, the crying, spitting up, and “pooping performances” (grimace, grunts, red face) aren’t caused by something harmful to baby. The best explanation is these are happening as the digestive tract matures. They are a sign of a healthy thriving infant!
Signs of Serious Intolerance That Suggest an Allergy
Serious signs of formula intolerance should be examined by a doctor right away. They suggest an allergy or a digestive disease that may cause your baby harm. Signs of serious formula intolerance include:
vomiting, may happen immediately after feeding or up to an hour later (Vomiting is forceful while spitting up just happens)
crying and fussing part-way through a feeding (volume limiting)
arching and red-faced crying after most feedings
feeding better while asleep (sleep feeding)
diarrhea
blood in the stool, with or without diarrhea
mucus in the stool, with or without diarrhea
slowing growth
inconsolable crying usually soon after feeding
Have your baby evaluated by her pediatrician if she shows any of these signs. If signs are happening with feeding, take a video to show your provider. Take a picture of what’s in the diaper if what you see concerns you.
photo credit: iStock
What Causes Formula Intolerance?
Formula intolerance is usually caused by two types of problems functional GI disorders and food allergies.
A food allergy is caused by an immune reaction to a specific protein. The latest evidence suggests that the gut microbiota plays a role in food allergies. Food intolerance on the other hand, can be caused by any ingredient -- protein, fats, or carbohydrates. And sometimes, there are signs of an intolerance like colic or spitting up, that aren’t really signs of medical problem. They are signs of a developing, ever-changing baby.
When the formula is a cause, figuring out the culprit of an intolerance is not always easy. Infant formulas have a lot of ingredients. Protein and lactose are often tagged as causes of formula intolerance. These ingredients are a place to look, but research shows that switching to formulas with hydrolyzed protein or reduced lactose doesn’t always work.
Switching formulas is a hefty topic and one that we’ll address fully in another article. The point to remember is that formula intolerance is not a simple topic, though an important one to parents. Let’s look at the two major causes for formula intolerance symptoms.
Infant Functional Gastrointestinal Disorders
As I mentioned previously, sometimes babies have signs of intolerance, but there a disease causing these signs. This is called a Infant Functional Gastrointestinal Disorders (FGID) or functional gastrointestinal disorders of infancy.
Infant functional GI problems are extremely common and very extremely concerning for many parents. One research paper estimates that about one-quarter (25%) of infants have functional GI problems. Another one showed that a little over one-third of infants who presented to hospital-based doctors had diagnosable FGIDs.
Even though the name includes the word “disorder”, FGID are not a disease as we commonly think of them. Giving medication or giving supplements will not usually help and may put the baby at risk because of side effects. The good news is that most babies grow out them in just a few days to weeks. However, these days and weeks can be hard on families. Your baby’s health provider should reassure you that everything is ok with your baby. Crying does not always mean that your baby is experiencing pain.
This is a time to pay close attention to your baby’s feeding cues. Some babies are easily distressed by even the slightest amount of over feeding. Check that you and everyone else who makes formula is mixing it correctly. Formula changes can sometimes help with FGID, especially if problems are with pooping. However, it is important to be very systematic with your formula changes and to not switch too fast from one to another.
Formula Intolerance and Pooping
When I present to health professionals about infant formula, I joke that it is impossible to talk about formula and not mention poop. It is an important topic! I’ve mentioned already that changes in poop can be signs of formula intolerance. Constipation may be the number one reason (no reverse pun intended) for visit to a gastroenterologist.
If hard poop is a problem, making sure to use a formula that contains prebiotics such as:
fructo-oligosaccharide
galacto-oligosaccharide
and/or polydextrose
These can help with softer stools and less straining with pooping. Choosing a formula without palm oil may also help some infants who are having hard poops. This is caused by the unique way that infants digest fats. The result is that the palm oil to joins up with calcium, making microscopic hard stones that make stool firmer.
Allergic Reactions to Baby Formula
A food allergy is best understood as a biological error, a sort of faulty alarm system. The immune system is constantly scanning the body ready to react to intruders by activating different biological processes.
In a food allergy, the immune system misreads a protein as a threat instead of nourishment. Threats must be protected against, and the body mounts an impressive “defense’, a set of common symptoms, which together are called an allergic reaction. The food that causes this reaction is called an allergen.
Allergic reactions to baby formula vary in time and intensity.
Allergic reactions can happen up to three days after eating the allergen, which can make it hard to connect the food to the symptoms. Delayed reactions are less severe than those that happen immediately. They don’t involve respiratory problems. However, skin problems like eczema are very common with a delayed reaction.
Photo credit: iStock
The Immune System and Food Allergies
Different parts of the immune system are to blame for the categories of food allergies. There are three food allergy categories.
Immediate reactions belong to a category called immunoglobulin E (IgE) mediated food allergies. The immune system makes an error in identifying the food proteins and makes IgE antibodies. These antibodies cause cells to release compounds that cause the allergic reaction symptoms.
Food allergies don’t have to involve IgE antibodies. They happen without IgE antibodies being produced. The category of food allergies is simply called non-IgE mediated food allergies . Problems with breathing do not happen with allergies in this category. Symptoms involve the digestive system and skin.
A third category of food allergies is called mixed IgE mediated allergies. In this category IgE are produced, but their presence only partially explains the reactions. The immune reaction is more complex.
Cow’s Milk Protein Allergy
Cow’s milk protein allergy is one of the most common food allergies in infants
A cow’s milk protein allergy usually causes more severe digestive symptoms than formula intolerance. Vomiting (which is different than spitting up), diarrhea or mucus in poop are very common symptoms and ones that parents recognize. Some infants only have the skin condition eczema. Infants with cow’s milk allergy, even mild ones, may not grow well.
If you suspect your baby has a cow’s milk allergy, make an appointment with your pediatrician right away. Also, don’t switch to a soy formula, because up to half of infants with a cow’s milk allergy are also allergic to soy.
Points to Remember About Baby Formula Intolerance:
Formula intolerance is not an allergy, but can have many of the same signs. Intolerance signs range from mild to very severe. If you suspect your baby has an allergy, see your pediatrician right away. Don’t make a formula change on your own.
Allergies can involve different parts of the immune system. Cow’s milk protein allergy is the most common
Don’t automatically blame formula for bothersome digestive symptoms. The infant digestive tract changes in the first months of life, which is normal and expected. Giving medications will not correct functional digestive problems.
Changing formulas may help with FGID. It is important to be systematic in your changes. Unfortunately research and clinical experience isn’t clear if formulas changes help digestion concerns that are function. Certainly, formula intolerance is very real and changing formulas can sometimes it can help. But I’ll be honest, it isn’t as straightforward as formula marketing says it is. One thing I’ve learned working with hundreds of families, is that digestive symptoms take time, patience, and caring to manage.
This article was updated on May 2, 2023 to provide more information about functional gastrointestinal disorders of infancy.