Pollen food syndrome: What is it and what do we need to do about it?

What is PFS and what can GPs do to help those affected? Find out more about this surprisingly common condition here from Dr Rob Walker

CREDIT: This is an edited version of an article that originally appeared on NB Medical

A quick look at the Met forecast shows the pollen count to be high or very high through most of the UK for most of April. A pretty common condition associated with the upcoming hay fever season is Pollen Food Syndrome (PFS). 

While some people may be vaguely aware of this condition (AKA oral allergen syndrome) some are very uncertain as to how serious the condition is, and what role GPs play. 

Luckily The British Society for Allergy and Clinical Immunology (BSACI) have produced recent guidance on this condition in 2022, with a very helpful GP specific section. 

And as it turns out this qualifies as a great GP condition – it can be diagnosed in most cases on history alone, no fancy tests needed, and can be managed with simple measures and advice. 

So what is PFS?

PFS is a common (estimated prevalence in the UK ~ two per cent) IgE mediated food allergy caused by a cross reaction between pollens (usually tree) and raw plant food allergens. 

In PFS the immune system is sensitised by pollens and then the person develops an IgE reaction to plant food allergens, which in their raw form are structurally similar to the pollens. 

The main pollens involved are birch, but also hazel and alder, and thus PFS usually develops in people with spring or summer time hay fever. 

The associated food triggers are widespread but common ones include stoned fruit (cherries, plums, peaches), other fruits (kiwifruit, pear, tomato), vegetables (celery, carrot, potatoes and other root veg) and some nuts (hazelnut, almonds, walnut, peanuts) and soya products. 

It’s important to note that it is only raw foods that trigger PFS – cooking denatures the food allergens. 

So what symptoms do people with PFS get?

After ingesting the raw food, people get immediate (within 10 minutes) mild itching/swelling of the oropharynx which resolves spontaneously over 30-60 minutes without treatment but can be eased with oral antihistamines. Peeling raw veg can cause itchy hands. 

Do we need to do any tests or refer to the allergy clinic? 

In the vast majority of cases no (but see caveats below). As the BSACI state ‘The diagnosis and management of PFS can often be wholly managed in Primary Care’. 

If the person reacts only to raw fruits, veg or soya, has typical mild symptoms with a background of spring hay fever, we can manage PFS in primary care without further tests or referrals. The BSACI leaflet has a good simple flow chart to follow. 

What advice do we give people with PFS?

They should simply avoid only those raw foods that have provoked symptoms. We should provide more detailed information (good info from Allergy UK here), and we should optimise any associated co-morbidities, especially rhinitis and asthma. 

If symptoms are unpleasant they can take an oral non-sedating antihistamine. We should obviously safety net to return if they start developing any symptoms that would need an onward referral. 

When do we need to refer?

Anyone who has severe symptoms (e.g. throat closure) or systemic symptoms needs referral to an allergy clinic, as does anyone who has reacted to nuts (even if the symptoms are mild) or cooked fruits/veg. 

If the person has multiple food triggers or there are concerns about an already limited/compromised diet we should consider referral to a dietician.

What about an adrenaline auto-injector (AAI)?

The majority of people with PFS do not need AAIs. If however they have had severe reactions, especially if they have concurrent asthma we should prescribe an AAI whist awaiting allergy clinic review, although in some cases the AAI may be discontinued by the allergy clinic.