Some people will experience mild symptoms when they have an allergic reaction but others can suffer more serious symptoms. The most severe type of allergic reaction is called anaphylaxis and it can be life-threatening.
The speed and severity of an allergic reaction may differ depending on whether you have an immediate or delayed food allergy.
Immediate food allergy
People with an Immediate food allergy (or “Ige-mediated” food allergy) often experience the symptoms of an allergic reaction as soon as they eat or drink the food they are allergic to. However, symptoms can begin up to 2 hours after.
Symptoms of a mild to moderate allergic reaction:
• Tingling or itching in the mouth
• An itchy red rash (known as hives) – sometimes this is raised but not always, and can look like stinging nettle rash
• Swelling of the face, such as lips and eyes
• Sneezing or itchy eyes
• Feeling sick or vomiting
• Stomach pain or diarrhoea
Symptoms of a severe allergic reaction (which can be signs of anaphylaxis)
• Hoarse voice, difficulty speaking or swallowing
• Swollen tongue
• Difficulty breathing, tight chest, wheezing or shortness of breath
• Feeling dizzy or lightheaded
• Persistent cough
• Floppiness or collapse
(see table below for more symptoms)
Anaphylaxis is a very severe allergic reaction which can be life-threatening and should be treated as a medical emergency.
It can affect your breathing or your circulatory system.
If you think someone is experiencing anaphylaxis, dial 999 and ask for an ambulance as soon as possible.
Professor Adam Fox says: “if you’ve been prescribed an adrenaline auto-injector, so an EpiPen or a Jext, this is the time to use it. Or if you’re not sure if the reaction is bad enough, you’re better to just get on and use it anyway, or if you don’t have one of those, call for help.”
Professor Adam Fox explains the symptoms of anaphylaxis (a life-threatening allergic reaction).
Delayed food allergy symptoms
Signs of a delayed allergy can take longer to appear and can be harder to identify and diagnose than an immediate food allergy. Symptoms can include:
• Worsening of eczema
• Changes in bowel pattern e.g., watery poo (stools) or constipation
• Gastric problems such as reflux, tummy ache
• Lack of weight gain and excessive irritability or inconsolable crying in babies
(see table below for more symptoms)
Does my baby have a food allergy?
Paediatric Consultant, Dr Neeta Patel describes the first symptoms you might notice if your child has an immediate or delayed food allergy.
A more detailed look at symptoms:
|IMMEDIATE FOOD ALLERGY||DELAYED FOOD ALLERGY|
|Tingling or itchy skin (pruritus)||Tingling or itchy skin (pruritus)|
|Red, rashy skin (erythema)||Red, rashy or flushed skin|
|Raised bumps, itchy red welts, called hives (Acute urticaria)|
|Swelling, commonly around lips, face and around the eyes (acute angioedema)|
|Sudden flare-up of eczema||Persistant eczema|
|GASTROINTESTINAL (GI tract from mouth to anus)|
|Swelling of lips, tongue and roof of mouth||Reflux|
|Tingling or itching in the mouth||Loose and/or frequent stools (poo)|
|Feeling sick (nausea)||Mucus and/or blood in stools|
|Sore, painful or uncomfortable stomach and abdomen||Sore, painful or uncomfortable stomach and abdomen|
|Vomiting (being sick)||Colic and irritability in babies|
|Redness around the anus|
|Tiredness, looking pale|
|Faltering growth in conjunction with other symptoms|
|BREATHING / RESPIRATORY SYSTEM|
|Cough that comes on suddenly, tight chest, wheezing, short of breath|
|Itchy nose, sneezing, runny nose, blocked nose (sometimes with conjunctivitis)|
|Anaphylaxis||Reluctance to feed|
|Floppy, pale, limp, difficulty in rousing|
Written by The Allergy Team, 18th March 2021
Dr Neeta Patel, Paediatric Consultant and Allergy Lead
Rachel De Boer, Dietitian with a focus on Paediatric allergy
Dr David Mass, GP with a special interest in allergy
1 Guidance | Food allergy in under 19s: assessment and diagnosis | Guidance | NICE
Diagnosis | Diagnosis | Cow’s milk allergy in children | CKS | NICE
Food allergy – Symptoms – NHS (www.nhs.uk)
Childhood Food Allergy | Free Symptoms Diary | Allergy UK
Disclaimer: All information provided by The Allergy Team Ltd is general information only. Please contact your GP or other qualified healthcare professionals for specific advice.