If you have a question that is not answered here then please have a look at our patient information leaflets which can be found in the Document section.
Below are some questions about allergies in general that we often hear asked.
Please click on a question to reveal the answer
What is FPIES?
FPIES or food protein-induced enterocolitis syndrome is an intolerance to food most commonly occurring in infants and preschool children. In the acute form it is characterised by severe vomiting that may cause hypovolaemia shock. Symptoms are delayed 2 – 4 hours after eating the food. FPIES is distinguished from food poisoning by the consistent nature of the reaction on repeated exposure to the food. In a subacute or more chronic form, diarrhoea also occurs, leading to failure to thrive and hypoalbulinaemia. Many foods can cause FPIES, the most common being cow’s milk, soya, rice and oats. The immune mechanism does not involve IgE and therefore allergy tests are not helpful. Resuscitation requires IV fluids. Adrenaline and antihistamines are not effective. The patient should be advised to avoid the food trigger and a referral made to an allergy specialist for further advice.
When should I refer a patient to a specialist?
This depends on your level of confidence and expertise.
- If you are not sure how to manage a patient, have a look through the Resource section of our website or give us a ring or email.
- If the patient has suffered from anaphylaxis, multiple or unusual allergic reactions, or you can’t work out what the cause is refer.
- If the child has eczema, allergic asthma or hay fever which is not controlled, even with good compliance with standard medication refer.
- If the patient’s life remains significantly impacted by their allergies refer.
- Patients with less common allergies, such as vaccine, venom or severe drug allergies should be referred.
You can refer to the tertiary allergy services by letter or using the NHS e-Referral service (previously Choose & Book). If you want advice in a shorter time frame, you are also welcome to phone or email.
What is an allergy focused history?
History is more useful than skin or blood allergy tests in determining if a patient has an allergy. The events and timing of the reaction should be recorded, as should the treatment given. Proceeding exposure to the suspected allergy is also important to record. Previous exposure to the allergen should also be recorded. If the history of allergy is unclear, then a supervised challenge to the allergen should be considered.
When should I order allergy tests?
Blood IgE tests and skin prick tests only provide evidence of allergic sensitisation that may be associated with immediate reactions. These tests are mainly used to support a clinical history of an acute reaction to the allergen. If there is no history of an allergy to that specific trigger, don’t do the test. If there is only a history of a delayed allergic reaction, don’t do the test. Don’t use the test to determine whether the patient has outgrown their allergy. They may be tolerant but the test can still be positive.
How do I interpret allergy test results?
Allergy tests may support the clinical history of an immediate allergy by providing evidence of allergic sensitisation to a particular substance:
- A positive test in combination with a positive history is a good predictor that the patient is allergic. The patient should be advised to avoid the substance, unless a direct physician supervised challenge proves the contrary.
- A negative test is a good predictor that the patient is not allergic to the substance. The patient should undergo direct challenge.
- A positive test in the absence of a clinical history of allergy to the substance is poorly predictive. The patient should undergo a direct challenge.
- A positive test in patients that have not had any reactions to cow’s milk and egg for 6 months or more is poorly predictive. The patient should undergo a direct challenge.
Are allergy tests useful for patients who only get delayed allergic reactions?
By definition, non-IgE mediated allergy, such as flares in eczema, cows’ milk proctitis, eosinophilic oesophagitis, FPIES are not mediated by IgE and therefore standard skin prick tests and specific IgE tests should be avoided in these patients as they are likely to either be falsely positive or negative. Patch tests for foods are also poorly predictive and not generally available. Patch tests for chemicals are sometimes useful for patients with a history of contact dermatitis.
Diagnosis of delayed allergies is by avoiding the food for a period of four weeks to see if the symptoms improve and then re-challenging to prove that the food actually causes a flare. For eosinophilic oesophagitis, referral to a gastroenterologist for endoscopy and biopsy is required for definitive diagnosis.
Setting up and supporting allergy clinics across the region
The objectives of an allergy clinic are to:
- Answer patients queries and concerns about allergy
- Diagnose allergies, including access to formal direct challenges
- Provide management plans for allergy, asthma, hay fever and eczema, with the help of specialist nurses, dietitians and other sub-specialists
- Promote patient competence and confidence in management of allergy (including use of an adrenaline auto injector if needed)
- Access to desensitisation services for patients with severe specific allergies
- Clinic staff need to be confident and competent in taking an allergy-focused history and in interpreting blood and skin prick test results. Skin prick tests are useful for supporting the diagnosis of immediate allergies. Competency in skin prick testing can be taught in any of the NW paediatric allergy centres.
- Allergy management plans can be downloaded from this NW Allergy site.
- Staff must be competent to deliver training and support families in using medication and devices. This can be taught in any of the NW paediatric allergy centres.
- Tertiary services at Alder-Hey Children’s Hospital and Royal Manchester Children’s Hospital are available to support colleagues in secondary and primary care with queries.
How many tins of specialist milk formula should I prescribe infants with CMPA?
To avoid waste, prescribe a maximum of one week’s supply (2-3 tins) until tolerance and compliance is established.
Once established on feeds a rule of thumb is to prescribed 10 tins a month for infants under 6 months, and 6 – 8 tins a month for infants between 6 – 12 months old.
All infants should be reviewed at least every 6 months to make sure that the formula is still needed.
For more information click here.
Should all allergy patients have an adrenaline auto-injector?
Not Always. The need for an auto-injector is dependent on the allergy, how easy it is to avoid and any underlying conditions.
Which adrenaline auto-injector (AAI) should I prescribe?
There are three AAI available in the UK: Emerade, EpiPen & JEXT. EpiPen & JEXT come in 150 and 300mcg doses, while Emerade also has a 500mcg dose pen. The Emerade 300mcg & 500mcg auto-injectors have a longer needle length than the EpiPen & JEXT.
All auto-injectors are designed for administration intramuscularly into the middle of the outer thigh. Resuscitation Council UK guidelines recommend the following dose of adrenaline is administered based on age of the patient: 6 years or under: 150mcg, 6 to 12 years: 300mcg, adults & adolescents over 12 years old: 500mcg
Based on these guidelines it is recommended that the 500mcg Emerade is prescribed for adults & adolescents over the age of 12 years old. For younger children any of the three auto-injectors could be prescribed in the dose detailed above.
Where should adrenaline auto-injector (AAI) be given?
In the anterolateral sector of the thigh halfway between the hip and the knee. This is because there are no major nerves or blood vessels and absorption is better than in the deltoid. This recommendation applies even in obese patients.
Which antihistamine should I prescribe for my patients?
Piriton (chlorpheniramine) is the best known antihistamine but its effects only last 6 – 8 hours and it is sedative. Prescribe if for children under 1 year old as it is the only licensed antihistamine in this age group.
For older children, consider prescribing one of the longer-acting, non-sedating antihistamines, such as cetirizine or loratidine.
Avoid first generation sedative antihistamines such as hydroxyzine (Atarax), promethazine (Phenergan) and diphenhydramine (Benadryl) which are not only very sedative but their action lasts up to a day affecting children’s ability to concentrate.
Who should have a food challenge?
- If you are unsure from your history and allergy tests whether the food needs to be excluded from the patient’s diet, then a challenge is needed.
- If the risks of the challenge is low (no previous exposure – negative allergy test; delayed allergic reaction only; challenge to baked milk or egg where there has been no allergic reaction to these baked products before) this can be done following guidance in the child’s home.
- In other circumstances, the challenge can take place in hospital.
- A food challenge is also appropriate before food desensitisation is undertaken. Food challenge is also recommended if the patient has no remembered experience of allergy, and wants to challenge their allergy, even if a reaction is certain.
Can allergies be cured?
No, most treatments for allergies aim to suppress the symptoms but none are a cure.
Desensitisation or allergen immunotherapy as it is also called, is one treatment that attempts to eliminate an allergy by making the body more tolerant of the allergen that triggers the reaction. But this is still not a cure and has to be repeated periodically. It should also not be considered lightly as there are associated risks which your doctor would discuss fully before recommending this course of treatment.
When might I consider desensitisation treatment?
Classically in patients with allergic rhinoconjunctivitis caused by pollen where regular use of an oral antihistamine, steroid nasal spray and non-steroid eye drops do not control the symptoms. Increasingly, we are using baked dairy and egg products e.g. biscuits and cakes to help toleralise children who are allergic to free milk or scrambled / boiled egg. Desensitisation may less commonly be considered for patients with peanut allergy, insect venom allergy or house dust mite allergy.