What is Cow Milk Allergy?
Cow’s milk allergy is frequently found in babies and kids. It typically shows up as an allergic reaction to the protein in cow’s milk. This allergy often appears in infants and can fade by the time they reach six years old. It can cause stress for parents and the whole family because it requires a diet without any milk. If not properly managed, it can also result in nutritional deficiencies.
What Causes Cow Milk Allergy?
Food allergies are caused by the body’s immune system reacting to certain foods. For example, if a person is allergic to milk, what happens is that their immune system will identify a specific protein in the milk as a threat. It will then activate an immune response to try and remove this perceived threat.
When this person comes into contact with that milk protein in the future, their immune system will remember it. This causes the immune system to act, releasing chemicals like histamine and others which are part of the immune response.
It’s this release of chemicals that results in the symptoms we associate with a milk allergy.
Risk Factors and Frequency for Cow Milk Allergy
Cow’s milk allergy is not easy to measure due to the lack of a clear definition for it. Sometimes, terms like “allergy”, “intolerance”, and “hypersensitivity” are used interchangeably. However, in developed countries, about 2 to 3% of infants seem to have this allergy. Despite some parents’ opinions, there is no proof that this rate is increasing. As children grow older, they are less likely to have this allergy. In fact, by the time they are six years old, less than 1% of them still have the allergy.
- Cow’s milk allergy is hard to define and measure.
- It affects about 2 to 3% of infants in developed countries.
- There is no evidence that the rate is increasing.
- Parents may think that the allergy is more common than it actually is.
- By the age of 6, less than 1% of children still have the allergy.
Signs and Symptoms of Cow Milk Allergy
Cow’s milk allergy typically shows up within the first six months of a child’s life, often appearing a few days or weeks after the child consumes cow’s milk protein. Symptoms can range from mild issues like diarrhea and vomiting to severe reactions such as anaphylaxis, which is a life-threatening allergic reaction. If the allergy affects the child’s gastrointestinal tract, they might become dehydrated and show signs of failing to thrive or not growing as expected.
The reactions to a milk allergy can be split into two categories: rapid onset, which occurs within an hour of ingesting milk and is usually due to an immune reaction (IgE mediated), and slow onset, which takes hours or even days to show up and is not IgE mediated.
Rapid onset symptoms include:
- Hives (Urticaria)
- Wheezing
- Itching or a tingling feeling around the mouth or lips
- Swelling of the lips, tongue, or throat (Angioedema)
- Coughing or shortness of breath
- Vomiting
- Anaphylaxis
Slow onset symptoms include:
- Diarrhea
- Blood in stool (Hematochezia)
- Abdominal cramps
- Intense crying and fussing (Colic)
In the case of anaphylaxis, which is a severe and potentially life-threatening allergic reaction, immediate medical attention is needed. Symptoms, which usually appear shortly after consuming milk, can include difficulties in breathing, airway constriction, throat swelling, facial flushing, and itching.
It’s important for doctors to distinguish between a milk allergy and a milk intolerance. The main difference is that intolerance doesn’t involve the immune system. Symptoms of milk intolerance, such as gas, bloating, or diarrhea after consuming milk, are typically less severe than allergic reactions. Also, the treatment for these two conditions differs.
Testing for Cow Milk Allergy
Diagnosing a cow’s milk allergy can be tricky as there isn’t a specific test to confirm it. Instead, doctors initially rely on the symptom history and a physical examination. They will take note of the symptom timeline and what triggers these symptoms. A detailed approach to diagnosing suspected cow’s milk allergy in infants might help determine if this condition is present.
Doctors may use certain tests like a skin prick test and serum-specific IgE measurement, though they are not always accurate. Both these tests are highly sensitive, meaning they can detect an allergy if it’s there. However, they have low specificity, which means they can sometimes show positive results even in non-allergic individuals. This means that a positive test doesn’t necessarily confirm cow’s milk allergy.
The serum-specific IgE test can help diagnose cow’s milk allergy when the immune system overreacts to normally harmless proteins. It’s important to note that the threshold values used in these tests can vary and should be set by an allergy specialist.
The skin prick test is performed by an allergy specialist. It involves using a tiny device to make a small prick on the skin to introduce a tiny amount of the allergen and observe if your body reacts to it.
Another approach to diagnosing cow’s milk allergy is through a diet elimination strategy. If a cow’s milk allergy is suspected, the infant is put on a diet that excludes cow’s milk protein for a month. If symptoms improve, doctors may then perform an oral food challenge test, the gold standard test, which must be done in a medical setting due to the risk of an allergic reaction. A reevaluation is required every 6 to 12 months to check if the child has developed tolerance to cow’s milk protein.
Determining a cow’s milk allergy can be a process with different paths based on the symptoms. Here’s a common approach:
1. If signs of severe allergic reaction or immediate reaction are present, doctors first recommend diet elimination. They may then order an IgE test. A positive result of this test along with symptoms improvement after diet elimination confirms cow’s milk allergy. If IgE is negative yet symptoms improve after diet elimination, an oral challenge should be next. If symptoms reoccur during the oral challenge, the diagnosis is confirmed. If the symptoms do not reoccur, then the diagnosis of cow’s milk allergy is likely ruled out.
2. If symptoms don’t fit with severe allergic reaction or immediate reaction, the recommended step is still diet elimination. If symptoms improve, an oral challenge should be done and if symptoms reoccur, the diagnosis is confirmed. If the symptoms do not reoccur, it excludes the diagnosis of cow’s milk allergy.
3. If symptoms do not improve despite the elimination diet, this generally rules out cow’s milk allergy. Further evaluation should be done to assess the patient’s condition.
Treatment Options for Cow Milk Allergy
The best way to manage any food allergy is to completely avoid consuming the food that causes it. For instance, for a child with an allergy to milk, they may need to follow a milk-free diet carefully planned with the help of a doctor or a dietitian to ensure it remains balanced and nutritious. The child may also need to take supplements to make up for the nutrients found in milk, such as calcium, vitamin D, and riboflavin.
Breastfeeding is generally recommended as it decreases the risk of cow’s milk allergy in infants. The rate of this allergy in breastfeeding infants is about 0.5%, lower than in those fed with formula. However, it’s important to note that proteins from cow’s milk can pass into the child through breast milk and might trigger an allergic reaction. Therefore, if the child is allergic to cow’s milk, the mother should also avoid consuming food containing cow’s milk protein, including cheese, yogurt, and butter.
Hypoallergenic formulas, which involve enzymes breaking down milk proteins, can also be considered. These formulas are either partially or extensively processed. However, it is safer to opt for extensively processed formulas since they are less likely to cause allergic reactions.
Although soy-based formulas might seem like a viable alternative, unfortunately, around 50% of children allergic to cow’s milk protein also develop an allergy to soy protein. Hence, these formulas are typically not recommended for treating cow’s milk protein intolerance.
Even alternatives like sheep and goat milk are not usually suitable because they have a high chance of causing similar allergic reactions due to similarities with cow’s milk protein. However, camel’s milk seems to cause fewer allergic reactions according to some studies.
In cases where a child accidentally consumes milk, medications like antihistamines can help reduce the mild allergic symptoms. On the other hand, if the reaction is severe, an emergency epinephrine injection may be necessary and a visit to the emergency room is advisable. If there is a risk of severe reactions, the child or the guardian might need to carry injectable epinephrine all the time. They should learn how to use this device correctly under the guidance of a doctor or pharmacist to ensure readiness during emergencies.
What else can Cow Milk Allergy be?
When trying to diagnose an allergy to cow’s milk, doctors have to consider a whole range of other conditions that might be causing similar symptoms. These other conditions include:
- Allergies to other foods
- Celiac disease (an allergy to gluten)
- Enteropathy (disease of the intestines)
- Stomach infections
- Enterocolitis (inflammation of the digestive tract)
- Inflammatory bowel disease (conditions causing inflammation in the digestive system)
- Meckel’s diverticulum (a bulge in the lower part of the small intestine)
- Angioedema (swelling underneath the skin)
- Lactose intolerance (inability to digest lactose)
- Idiopathic urticaria (unexplained hives)
- Anaphylaxis (a severe, potentially life-threatening allergic reaction)
It’s important to understand that doctors need to carefully explore all these possibilities before they can accurately diagnose an allergy to cow’s milk.
What to expect with Cow Milk Allergy
The outlook for infants and young children with a cow’s milk protein allergy is generally positive. About half of these children overcome their allergy by the time they are 1 year old, roughly 75% outgrow it by 3 years old, and more than 90% are free from this allergy when they reach 6 years old.
However, kids with a milk allergy are more prone to developing allergies to other foods. Reactions to various foods can occur in up to 50% of these children. Also, between 50% to 80% end up developing allergies to airborne substances before they hit puberty.