Gold standard is double blind challenge, but who has time for that?

Mostly based on history – combination of characteristic features without other, more likely, explanation.

NICE has list of type 1 vs non type 1 allergy signs/symptoms – some overlap, eg vomiting, diarrhoea, itch.

EAACI guidance 2023 says where type 1 allergy suspected (signs/symptoms but also timing and consistency of reaction):

• Do skin prick testing and/or specific IgE testing as first line
• For peanut, hazelnut or cashew, if in doubt do component tests Ara h 2, Cor a 14, Ana o 3 respectively as well (if available) – otherwise do skin prick or IgE if not done already.
• Where peanut or sesame allergy still in doubt, do basophil activation test (BAT – if available)
• “Reassessment of food allergic children, at regular intervals, depending on age, food and patient’s history, is suggested for possible development of spontaneous tolerance”

Ara h 2 (cut off 0.44) has 82% sensitivity and 92% specificity cf 84 and 86% for SPT of 4mm. Cor a 14 (cut off 0.64%) has 73 and 95%, Ana o 3 (cut off 0.4) 96 and 94%.

Common hidden allergens (!): celery, mustard, cochineal, lupin, soy, fenugreek, other legumes such as pea/bean/lentil protein, insects/mealworm, pink peppercorns).

Proteins responsible for a minority of allergic reactions to peanut, hazelnut, sesame among others – hydrophobic, so tend not to be well represented in skin prick and IgE test solutions. May explain false negatives.

Specific IgE tests have been developed, but otherwise you just have to challenge.

Dutch study however didn’t find that specific testing for oleosins helped much.

First do no harm – parents tend to overestimate risk of anaphylaxis, whereas there are clear consequences to restricting the child’s ability to sit with other children at snack/meal times, or restricting the food choices of other children.

Probably better to increase allergy awareness (which varies widely) than rely on classroom or school-wide bans [Dave Stukus editorial]

George Raptis has shown how allergy training can improve allergy awareness, not just confidence in managing an allergic emergency.

Alliums, as are leeks, shallots and chives. Part of same bigger family as asparagus but probably not co-sensitivity.

The main issue with onion is the chemicals released from cut surfaces, which can trigger eye/nose reactions and potentially asthma. But there’s actually some evidence that onion has an anti-allergy action.

With garlic, there is a well recognised contact dermatitis relating to chopping it.

Otherwise, allergy is very rare. Potentially part of celery-spice-mugwort syndrome.

As with that syndrome, the problem for the allergic person is that not only is it not one of the 14 UK recognised allergens for food labelling and restaurants, but it can be included under “spices” if less than 2% of the overall product, without further detail.

Different from intolerance and sensitivity, which are not immune mediated problems. Sometimes hard to tell the difference.

2 types of food allergy, you can have both at the same time – type 1 (IgE mediated), and non-type 1 (non-IgE mediated – possibly type 4 hypersensitivity).

Most commonly (in Scotland – but varies across UK, especially with different ethnic groups), and varies widely across the world):

• Milk
• Egg
• Peanut
• Tree nuts
• Legumes/Pulses
• Sesame
• Wheat
• Crustaceans/molluscs
• Various fruits

Patient/parent feedback pretty consistent across the world however (although most studies done in Europe and English speaking countries), and across time:

• Parents lived in fear after the first reaction, often perceiving it as traumatic, and often feeling guilt too
• They tried to live an ordinary family life and had to learn how to be one-step ahead and understand early signs.
• The family’s social life was also influenced.
• Parents asked for support and information from health professionals
• More knowledge and skills increased parents’ confidence (and by implication quality of life – Knibb 2015)

Mothers tend to report greater impact on the child’s quality of life and experience more anxiety and stress than fathers. Mothers tend to shelter the child, whereas fathers more often express a desire to expand their child’s life, and these differences are often greater where parents are separated.

The concern for the child’s safety affected eating outside the home, with birthday parties and visits to peers’ homes particularly threatening. School and nursery are a major source of concern and often led to more parental work, preparing safe lunches.

Parents often felt they had to teach themselves about allergies, due to the lack of early information provided by health care, and then ended up having to teach family, friends and educational institutions too.

Adolescence is a particularly stressful time, as parents recognize the need for the child to become more independent, at the same time that the adolescent can see the parents as excessively controlling (at least with respect to peanut allergy). Supportive friends particularly important for adolescents.

[Larsen Moen, J Ped Nursing 2019]