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Infant Food Allergy Reaction Timing: When They Start & What To Look For

No matter what type of food allergy reaction your baby has, it’s terrifying. Whether it’s trouble breathing or a nasty rash, you want to be prepared.


Free To Feed’s your infant food allergy support system — here to educate, provide resources, and give you confidence on your food allergy path.


How long reactions last can become a revolving door. You think you’ve hit baseline and bam — another reaction. Or you realize you consumed a hidden allergen, grr. It’s hard to nail down triggers with food allergy symptoms, and reaction times only add to the confusion.


Today we’re diving deeper into when allergic reactions occur, how long they last (depending on what’s affected), and how you’re never alone with Free To Feed.


The Most Life-Threatening Allergic Reaction? Anaphylaxis!


Did you think of someone reacting horribly to peanuts or latex, like they show in the movies? The person will likely look like they can’t breathe and someone’s quickly coming to the rescue.


When a baby can’t breathe after consuming an allergen, that’s 1 critical body system failing (lungs). But that doesn’t happen nearly as often as you’d think.


If 2 non-critical body systems fail (skin and stomach), it’s considered anaphylaxis! Hives and vomiting are the most common anaphylaxis reactions in babies.[1]


This reaction’s the most life-threatening allergic response and can lead to death. Hard to even put into words when it comes to your child, and we want to do everything possible to prevent this trauma for your family.


Anaphylaxis happens so fast because the body’s immune response creates a burst of IgE antibodies that often affect multiple areas of the body at the same time (lungs, GI tract, skin, etc).


Anaphylaxis usually occurs within 5-30 minutes after exposure — but can take up to 1 hour.[2]


Warning signs include:

  • Red rash

  • Hives/welts that itch

  • Swollen throat

  • Trouble breathing

  • Passing out

  • Vomiting

  • Pale or red color to the face

Get immediate medical attention, and work closely with your child’s allergist or immunologist. If your child has an IgE allergy, we hope you’ve been shown how to use the life-saving epi-pen. (Thank you, medical science!)


Most babies that experience an anaphylactic reaction, and get the medical attention they need, are very sleepy after it’s all over. Their little bodies went through a lot, so don't be surprised if they need more snuggles that day or night. (We know you will too!) Let’s look into other food allergy responses to watch out for.


How Long Skin Reactions Last For A Food Allergy Baby


Research suggests that up to 40% of children with eczema and skin conditions could be experiencing a reaction from food allergies.[3] Battling skin ailments like eczema can feel like a spinning wheel — it gets better and then worse. Better again, then way worse. It’s beyond frustrating and makes it harder to find the source.


Skin reactions (not hives) from food allergies are often delayed up to 4-6 hours after exposure. [3] Research indicates that skin flares for some take up to two days for it to peak.


Leaving you scratching your head — from six hours ago… *squints eyes*


Laundry detergent?

New lotion?

Different brand of seasoning?


We know it’s discouraging but finding the cause gets your baby to baseline fastest. Our consults get specific with your family’s unique case and feeding goals. We know everyone has different needs.


The good part? Usually, skin begins to heal within 48 hours — after removing the confirmed allergen from the diet.


Your baby’s ultra-sensitive skin needs tons of extra moisture! Read more from us about eczema in pictures here and treatments for home here. Next, let’s travel into the delicate digestive tract of our food allergy babies.


Infant Food Allergy Gastrointestinal (GI) Responses Vary