What Does an Allergic Reaction Look Like?

When it comes to parenting, you need to be ready for any scenario that may arise with your baby.

One unfortunate, but relatively common scenario is an allergic reaction to food. Hopefully this never happens, but it is possible given the growing number of people who are susceptible. About 15 million people across the United States alone have food allergies, most of which stem from childhood. 

Babies with allergies react differently to foods that are typically harmless. The body’s immune system works to defend against (what it perceives to be) dangerous substances, in this case food. As a result the baby’s immune system will react in self-defense, causing an allergic reaction.

Although there are hundreds of foods that people are allergic to, the majority of all allergies stem from just 8 foods. The most common allergens (foods people are allergic to) are:

  • Milk
  • Egg
  • Peanut
  • Tree nuts
  • Soy
  • Wheat
  • Fish
  • Shellfish

This is not to say that you should avoid feeding your baby these foods. Instead, the intention is to raise awareness as you introduce new foods to your baby’s diet. As a parent, the last thing you probably want to worry about is your baby having an allergic reaction to food, yet you need to be aware of the potential causes.

When it comes to food allergies, you don’t want to risk your baby’s health. That’s why it’s important to understand the symptoms of an allergic reaction, what to do if it happens, and how to prevent them in the first place.


In self defense, a baby’s immune system will release antibodies throughout the body. As they are released, they cause various symptoms to appear. Certain symptoms are more mild, whereas others can be life threatening so it is important to identify the signs early.

1. Common and Mild Symptoms

Two of the more mild symptoms that may occur are hives and vomiting. Hives are red bumps that may appear throughout the baby’s body or in specific locations. At times these hives can be mistaken for eczema or vice versa. 

Vomiting is the other common symptom among babies. Since vomiting may happen for a variety of reasons, it’s important that you observe your baby closely after introducing them to new foods. When a baby has an allergic reaction to food, symptoms will occur shortly after consumption. It could be anywhere from seconds to at longest 2+ hours afterwards.

2. Additional Mild Symptoms

In addition to the most common symptoms, there are other signs that you should be aware of. Keep in mind that everyone is different, so one baby might display certain symptoms more than others, while another baby could react entirely different. Additionally, your baby may react one way initially, then have different reactions in the future to the same food.

Swelling is a major signal of an allergic reaction to food. Typically, this will occur in the facial region so look out for lips, eyes, and other swelling that presents itself on your baby’s face. 

Additionally, you may see reactions involving other parts of the body including:

  • Skin
  • Eyes
  • Gastrointestinal (stomach aches)
  • Mouth (swollen tongue)
  • Respiratory (breathing)
  • Cardiovascular (heart rate)

Some symptoms are more alarming than others. In fact, babies may react differently to the same food depending on their body’s interpretation, that’s why you need to be aware of the varying possibilities.

3. Beware of Anaphylaxis 

This is the most dangerous state of an allergic reaction. In fact, it can be life-threatening in a worst case scenario.

Symptoms of Anaphylaxis include difficulty breathing and shock. It can occur at the same time in various parts of the body and may be accompanied by other symptoms as well. Beware that this may start as a mild reaction and progress.

In the event of any allergic reaction, whether minor or major it is important that you know exactly how to respond. Don’t take any reaction lightly.

What to do if Your Baby has an Allergic Reaction

Seeing your baby have an allergic reaction would be anxiety inducing and nerve wracking. With your baby’s safety on the line, though, it is important that you have a plan of action. Depending on the type of reaction your baby has, there are certain actions you should take.

Common and Mild Symptoms

In the event that mild symptoms present themselves when your baby eats a certain food, there are multiple things that you should do.

First, you need to stop feeding your baby the food that caused the reaction. You should not introduce more than one new food to your baby at a time so that it is easy to identify the cause when it happens. Additionally, you need to continue to monitor your baby even if they present mild symptoms. This can progress to Anaphylaxis, so no reaction should be taken lightly.

Before feeding that food to your baby ever again, you need to seek medical advice from your pediatrician and (if recommended) an allergist. These experts will help rule out other potential causes for the reaction and help take next steps to keep your baby safe.

Learn more about the signs of an allergic reaction from Dr. Shelly Flais of the American Academy of Pediatrics:

Severe Reactions

If a worst case scenario were to arise, there are immediate actions you need to take. This can be the difference between life and death, so there is no time to waste. 

Start by calling 911. Tell the responder that your baby is having an anaphylactic reaction. Having medical professionals on the way is crucial because they will have prior experience dealing with these scenarios and be well-versed in what to do to try to save your baby.

In the meantime, you need to inject the baby with epinephrine using an EpiPen or AuviQ. This is the only medication that will stop anaphylaxis. Eventually, when the ambulance arrives, you will need to be able to tell them when your baby was injected.

You should also lay your baby flat in your arms.They should be lying down, not in an upright position or walking. However, sometimes anaphylaxis causes shortness of breath, if this occurs, sit them up. Other potential scenarios include fainting or vomiting. If these occur, lay the baby on their side because laying flat in this cause would potentially cause the baby to choke.

Finally, it is important to point out that second reactions 4-24 hours afterwards are also possible. These are called biphasic reactions, in which symptoms get better and then worse. Follow the same steps as above in the event that this occurs (note that you should have 2 Epipens for exactly this reason).

*Please note always consult with your health care provider if you think your baby is showing signs of an allergic reaction.

How Parents Can Take Preventative Measures

Perhaps the best way to combat allergic reactions is to stop them before they ever begin. As a parent, you can make a huge difference in whether your baby develops a food allergy. 

Naturally, you might assume that avoiding allergens is a great way to protect your baby from food allergies. This could not be further from the truth, If you want to defend against food allergies, you need to meet them head on.

Exposing your baby to allergenic foods (see the top 8 listed at the beginning of this article) is the best way to prevent allergies. In fact, studies show that almost 80 percent of food allergies can be prevented using this method. 

The USDA guidelines produced in 2020 make it clear that babies as young as 4 months old should get exposure to allergenic foods. Early introduction helps your baby build immunity overtime. Start with peanuts, eggs, and milk because these represent over 80% of the most common childhood food allergies.

Introduce one at a time waiting at least 3 to 4 days before trying something new. That way, it is easy to pinpoint foods that cause an allergic reaction (if any). The other essential component to this process is repetition. Each food previously mentioned needs to be continually fed to your baby to build up immunity over time. 

Key Takeaways for Parents

Understanding allergic reactions and how to prevent them are critical for all parents. You can have a tremendous impact on your baby’s well-being by knowing the symptoms of an allergic reaction, what to do if it happens, and how to prevent them in the first place.


All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease. 

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