Type 1 hypersensitivity reactions to food are usually (but not always) associated with one or more of:

• Cutaneous (e.g., itchy, rash, swelling)
• CVS (e.g., dizzy, collapse)
• Respiratory (e.g., sob, wheeze)

and occur within minutes of ingestion (typically less than 1 hour, although can be longer if wheat, red meat, or shellfish implicated, or exercise co factor).

If there are associated systemic features refer to anaphylaxis guidance (see Red Flags).

Non-type 1 hypersensitivity reactions to food (food intolerance) are often gastrointestinal only, and the timing is often not suggestive of type 1 hypersensitivity. See here for more information.

Eczema alone is not caused by food allergy in adults, and this should not be a focus of investigation.

Clinical history and documentation of reactions is paramount. Document all new reactions promptly and thoroughly to assist in future investigation.

Include:

• Foods and medications consumed within 4 hours prior to the reaction
• Activities/exercise/exposures over that period
• Tolerance of these foods/drugs since the episode (this excludes these as a cause of the reaction).
• Any dietary implications (e.g., nut allergy in a vegetarian or coeliac disease patient).
• Any other foods that are avoided and the reason for avoidance.

If there are associated systemic features refer to anaphylaxis guidance.

Anaphylaxis is an acute severe systemic reaction which is most often allergic (but can be non-allergic, previously called anaphylactoid).

It is commonly associated with urticaria and angioedema and occurs within minutes (typically less than 1 hour) of a trigger (e.g., food/drug/sting). Anaphylaxis is characterised by one or more of:

i) Airway – tongue/throat swelling, difficulty talking/hoarse voice

ii) Breathing – shortness of breath, wheeze, persistent cough

iii) Circulation – persistent dizziness or collapse, loss of consciousness

iv) Neurological – sense of impending doom, visual changes

Anaphylaxis should be treated immediately according to Resuscitation Council guidelines and the patient referred to hospital for acute measurement of mast cell tryptase and further management.

• No investigations in primary care are required prior to referral.
• If Specific IgE is requested prior to referral it should only be done for foods known to be involved in the reaction.
• Please note, a negative Specific IgE is not sufficient to rule out a food allergy. Patients must continue to avoid any foods implicated in reactions.
• Tolerance of the implicated food since the reaction excludes allergy.
• Patch testing, skin prick testing, and oral food challenges should not be undertaken in primary care.

1. Advise patients to avoid potential triggers identified in the history pending further investigations.

Advise particular caution when eating away from home or with food not prepared by the patient.

If a suspected trigger has been tolerated since the reaction it is excluded as a cause.

2. All patients should be provided with an emergency plan.

• GPinformation-AnaphylaxisactionplanWITHadrenaline.pdf
• GPinformation-AnaphylaxisactionplanWITHOUTadrenaline.pdf

a. Self-injectable adrenaline should be prescribed

i. Where there were features of anaphylaxis (airway, breathing, circulation, or neurological),

ii. For all patients with food allergy and a history of asthma

iii. For patients where access to emergency services might be delayed (e.g., living in a rural location, travelling to remote area with limited access to healthcare)

3. All patients must have appropriate training in their use.

Please see 3.4.3 Allergic emergencies for Formulary Guidance on prescribing.

a. Adrenaline should be co-prescribed for patients with cardiovascular disease on betablockers and/or ACE inhibitors with caution.

b. Asthma care should be optimised.

c. Any patient with a tendency to angioedema should avoid ACE-I.

4. The use of unorthodox methods of diagnosis (e.g. naturopathy, food-specific IgG testing, vega testing, kinesiology, pulse testing, hair analysis) or treatment (e.g. homeopathy, acupuncture, reflexology, chiropractic therapy, or osteopathy) has no evidence and should not be used.

The information essential for clinical triage is outlined on the referral form.

For efficiency and to minimise returned referrals, use of the referral form is recommended.

Referrals not on the referral form will be accepted as long as all the essential information is included in a referral letter.

Referral Criteria

Adults (16 years or over):

1. With suspected food allergy

2. With suspected food reactions where food trigger is not clear (e.g., negative specific IgE testing to the suspected food).

3. With suspected food allergy where multiple foods are implicated

4. Where food avoidance would cause important dietary restriction (eg nuts in a vegetarian or coeliac disease patient)

5. Where the food allergy has occupational implications (e.g. military employment).

Referral Instructions

Refer to Peninsula Immunology and Allergy Service

Refer via DRSS for NHS Devon patients

e-Referrals Selection

• Specialty: Allergy
• Clinic type: Allergy
• Service: DRSS-South Devon & Torbay-Allergy- Devon ICB - 15N

Referral Forms

Adult allergy clinic referral form - no merge fields

Patient Information

MyHealth - Allergies

This guideline has been signed off on behalf of NHS Devon.

Publication date: March 2016

Updated: December 2024