The most common triggers for anaphylaxis include:

  • food

    • especially peanut, tree nuts such as almonds, pecans, cashews, walnuts

    • fish and shellfish

    • cow’s milk

    • egg

  • insect stings

  • medications (most commonly penicillin)

  • latex

Symptoms include one or more of:

  • Hives, itching and redness of the skin, lips, eyelids, or other parts of the body, and/or itching of the throat, tongue, and mouth 

  • Wheezing and/or difficulty breathing 

  • Swelling of the tongue, throat and nose

  • Nausea, vomiting, diarrhea, or cramping pain in the abdomen 

  • Dizziness and fainting or loss of consciousness, which can lead to shock and heart failure

Usually, it is possible to establish a cause of anaphylaxis by using one or more of the following diagnostic modalities; allergy history, examination, skin testing and specific IgE blood testing. If a cause is not established this is known as Idiopathic Anaphylaxis. Anaphylactic variants include food-dependent exercise-induced anaphylaxis (FDEIA), exercise-induced anaphylaxis (EIA), and hormonal anaphylaxis.

Read more on Anaphylaxis

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Asthma, Bronchiolitis, Wheezy-cough, Bronchial Asthma, Cough variants

There are many different 'chesty conditions' in childhood. Whilst 1:2 children will wheeze at some stage of early childhood, few of these children will go on to develop classic asthma. Dr Du Toit is happy to perform diagnostic tests and plan management strategies for these different conditions.

Dr George Du Toit's initial research was in the field of respiratory medicine. He has significant experience in the management of asthma and is able to design personalised treatment plans, which aim to safely minimise therapies whilst improving asthma control.   

Asthma is frequently associated with aero-allergies, such as house dust mite, pollens (tree, grass, weed), moulds, animal danders and even foods. Children with allergies to more than one food or severe food-related symptoms have a 6-8 times increased risk to develop asthma compared to children with no food allergies. Immunotherapy may be needed to desensitise an individual to one or more of these allergens.

For a list of the common aero-allergens that are important for the prevention and treatment of asthma, please click here. 

In sensitised children, targeted avoidance measures (such as using dust mite mattress covers to minimise exposure to house dust mite or ‘getting rid of the cat’) may lead to an improvement of symptoms and reduction in need for medication. You can download handy Top Tips for Children with Dust Mite Allergy here. Dr Du Toit will discuss these measures in clinic with you.

We offer specialist training in the indications for, and use of, asthma inhaler devices.

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Chronic Urticaria and Angioedema

Dr Du Toit has a special interest in chronic urticaria (CU) and is co-author of the BSACI recommendations for the investigation and management of CU

Acute urticaria is a common disorder for which a cause is frequently apparent. A cause is less frequently established for intermittent and chronic urticaria (CU).

CU is a condition of urticaria (also called hives, welts or wheals) that persist over some 6 weeks. Angioedema (swellings of the lip and eye lids) is associated in 80% of cases. CU typically arises in otherwise healthy individuals. CU is not an allergic condition, but allergies may coexist (like in any other individual). CU is usually an 'auto-immune condition' where the immune system wrongly targets skin cells (mast cells). This process results in the itchy skin and mucosal hives and swelling. Patients with CU have a significantly impaired quality of life. 

Despite recent advances in the field of CU, the investigation and management thereof remains a clinical challenge. CU is frequently over-investigated and when investigations are performed, they are frequently inappropriately selected. 

Allergy to foods or food additives is seldom ever a cause of CU. The condition is usually of an 'auto-immune nature', that is, functionally active auto-antibodies to the high affinity IgE receptor (FcepsilonRI) or the IgE antibody itself. Dr Du Toit is able to investigate for these auto-immune factors. To do so he will send blood to the Reflab in Denmark for Basophil Histamine Release Assay testing. In addition, select patients will need to undergo Autologous Serum Skin Testing (ASST) on the day of their appointment.

The frequent urticarial lesions, and mucosal swellings (angioedema) prove embarrassing and uncomfortable. Patients with CU are often inadequately treated. Dr Du Toit will tailor a treatment regimen that gains control with as few possible side effects. 

Dr Du Toit will test for auto-antibodies as these are usually present in 40-60% of cases. If present they predict for a more prolonged disease course, often requiring high-dose antihistamines. Associated autoimmune conditions e.g. Thyroid Disease and Vasculitis, are occasionally associated; will also be excluded on screening.

CU will not result in life threatening swellings of the throat. CU can be outgrown in childhood; a history of concomitant allergic conditions and more frequent episodes of urticaria were associated with a poorer prognosis.

High-dose non-sedating antihistamines are the medication of choice for prophylaxis, and treatment, of symptoms. Trials off therapy are encouraged during holidays and over weekends (to see if remission has been achieved). Exacerbating factors may include; pressure to the skin e.g. under a tight belt, vibration, ultraviolet, hot temperatures and salicylate medications.

Prof Du Toit is also able to administer monthly Omalizumab injections which are often successful on significantly improving control of CU symptoms.

App to track your hive severity

Paper on CU

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Drugs, Antibiotics and Anaesthetic

Dr Du Toit has a special interest in drug allergy. The investigation of drug allergy can be a challenging and potentially risky task and is best performed by centres with specialised skills.

Common drug allergies include those which arise due to antibiotics, pain killers, local and general anaesthetic agents.

The incidence of adverse reactions to drugs of the overall population is estimated to be around 15%. Numerous immune mechanisms are implicated in drug allergy and the incidence of immediate drug reactions (Type I) seems to be very low in comparison with allergy to more common allergens such as pollens and pets. The incidence of allergy to penicillins is 1/1000 administrations, i.e. 0.7 to 10% of treatments.

Antibiotic Allergy: Only a minority of individuals 'labelled' as being antibiotic allergic are truly allergic to antibiotics. The index rash experienced is usually caused by the viral illness for which the antibiotics were prescribed.

A detailed history is required of the nature and timing of the rash in relation to taking the antibiotics. Please bring along as much clinical information as possible, for example, a copy of anaesthetic charts or antibiotics used in the past.

Investigations: TDL Lab allergy blood tests will be performed, depending on the drug. A further Skin Test may be required to confirm or refute the diagnosis of a particular drug allergy. A decision will then be made wrt performing a supervised oral incremental challenge to the specific Antibiotic.

If a drug allergy is established, Dr Du Toit attempts to identify alternative medications for use in the future.

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Eczema (Atopic Dermatitis)

Food Allergies & Eczema

The relationship between food allergies and eczema is complex. Dr Du Toit works closely with dermatology colleagues to optimise eczema control and to minimise discomfort and itch.Foods such as tomato, pineapple, citrus and berries (which are sometimes low in ph - due to natural acids and high in histamine) may irritate facial eczema. These foods should continue to be eaten but will be best tolerated when eaten cooked, and after the application of a thick moisturiser e.g. Lucas’ PawPaw Ointment (buy online) or Vaseline to any dry skin or eczema around the mouth.

Chickenpox Vaccination

Dr Du Toit is now offering the VZV vaccine for his patients; this vaccine is not routinely offered on the NHS but is standard in many countries including most of Europe, USA and Australia. Dr Du Toit recommends this vaccine for all children who have not had the disease but particularly for those children with troubling eczema (as they are at increased risk of complications from the virus). It is also recommended for all children 13 yrs or older who have never had chickenpox.

Safety and Efficacy

Re safety and effect on later onset shingles please read the following 2 informative resources (a) and (b) 

If you have already attended: thank you for attending for vaccination against chickenpox.


a) In the UK a single vaccine administration will offer about 80% protection in children; some families wish to wait to see if natural exposure to chickenpox has occurred by school entry after the first jab; if not, then a booster shot is recommended

b) Alternatively, the recommended 2 dose schedule can be completed (all included in initial charge); this offers up to 98% protection in children and slightly lower in adolescents. Those who develop a ‘breakthrough’ infection to the ‘wild’ strain usually experience a very mild disease course. This is is Dr Du Toit's preferred option. Please book with Lynn if you wish for the second vaccine to be administered.

For people older than 13 the two doses are administered 4 to 8 weeks apart.

 Further Information

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Eosinophilic Oesophagitis and Colitis

This mixed group of conditions arises due to eosinophilic cellular infiltration and inflammation in the gut. Different gut regions can be involved and the condition is therefore best classified according to the site of the inflammation. The site of involvement will influence presenting symptoms; these may include growth failure, persistent nausea, food aversions, gastro reflux, non-specific abdominal pain, anaemia, food aversions... Indeed, each patient typically presents with a slightly unique clinical picture.

Dr Du Toit works closely with leading London Paediatric Gastro-Enterologistis to manage this sometimes complex and stubborn condition. A biopsy done through a GI scope, under anaesthesia, is usually required in order to make this diagnosis.

The range of anatomical involvement includes Eosinophilic Oesophagitis (EO, or known as EE in the USA) - this is the most common of these conditions. Eosinophilic Gastroenteritis and Eosinophilic Gastro-Enterocolitis are other subtypes. 

EO is clearly associated with atopic individuals making allergy testing a must in this condition. Treatment consists of the supervised dietary-exclusion but additional medications are nearly always required.

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Food-protein Induced Enterocolitis Syndrome (FPIES)

Food protein induced enterocolitis syndrome (FPIES) is an under-recognised, and frequently misdiagnosed syndrome. It has been described as a 'weird food allergy'. It is characterised by severe protracted diarrhoea and/or vomiting, and is frequently associated with sepsis-like symptoms, such as pallor and/or lethargy. Symptom onset is usually soon after ingestion of the causal food protein. 

Although typically ascribed to cow’s milk and soy, FPIES has also been described after the ingestion of a wide range of food proteins. FPIES is thought to represent a severe cell-mediated, gastrointestinal food hypersensitivity.   

The presentation of the syndrome varies from mild (e.g. non-dehydrating vomiting and/or diarrhoea) to severe symptoms. Symptoms may change rapidly and manifest as a state of dehydration. Hypovolaemic shock is present in up to 20% of cases. Understandably, a combination of vomiting, lethargy and resulting acidosis leads to a primary diagnosis of sepsis. In this clinical scenario, the dietary history may not receive prominence, with the result that the syndrome recurs with each subsequent ingestion of the food protein. Failure to recognise the link with diet may lead to multiple intensive or high-care admissions, due to supposed recurrent sepsis. The incidence and prevalence of FPIES is not known. 

Common triggers include: Cow's milk, soy and fish. Many other foods have also been linked to the syndrome.


Key points:

  • FPIES pathogenesis is probably non-IgE-mediated, so culprit food-specific IgE investigations are often negative.

  • The period of life during which FPIES appears most frequently is the first 9 months after birth.

  • The most frequent culprit food (except in Australia) is CM.

  • The most frequent solid food that induces FPIES in Italy is fish, while worldwide it is rice.

  • Common FPIES symptoms are vomiting, hypo-reactivity, hypotonia and sometimes diarrhea.

  • The evolution of FPIES is benign in a few hours; but seldom immediately as is the case in IgE-mediated food allergy.

  • Diagnostic criteria consist of the occurrence of at least two typical episodes.

  • There is often a diagnostic delay – as many as six episodes could take place before the situation is clarified.

  • Acute therapeutical measures are iv. fluids and cortisone.

  • Dietetic measures consist of eliminating the culprit food from the patient's diet.

  • As far as prognosis is concerned, there is a good chance of achieving tolerance at 18 months if the responsible food is CM; however, there aren't enough data for other foods.

Food-Protein Induced Enterocolitis Syndrome (FPIES) Review

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Food Allergy

Food allergy is a large subject and has its own FAQ and detail section here.

Dr Du Toit has a research interest specifically in the field of Food Allergy and is able to offer the latest diagnostic tests for the investigation thereof.

Background Information re Food Allergy:

IgE-mediated food allergies, also known as immediate-onset food allergies, are most prevalent during childhood, affecting between 6 and 8% of children in the UK. The following food allergens account for the majority of food-induced allergic reactions in young children

  • Cow’s milk

  • Hen's egg

  • Peanut, tree nut

  • Sesame

  • Wheat

  • Seafood (finfish, shellfish and molluscs)

  • Soya

  • Kiwi

  • Celery (Celeriac)

  • Fruit allergy, including Oral Allergy Syndrome and kiwi allergy

  • Legumes

  • Lupine

As not all food allergies are outgrown, finned fish, shellfish, tree nut and peanut allergies are the most common allergies in adulthood.

Cross-reactive allergic reactions in pollen-allergic children and adults are common and known as the Oral Allergy Syndrome (OAS). An example of this syndrome is the teenager allergic to birch pollen and who experiences oropharyngeal tingling when eating an apple.

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Food Intolerance, Irritable Bowel, Coeliac Disease, Constipation, Lactose Intolerance

Irritable Bowel Syndrone (IBS)

IBS is a common gastrointestinal disorder that is a diagnosis by exclusion. IBS symptoms include abdominal pain, which can be severe, bloating, excess wind, and alteration of bowel habits. These symptoms can be slow to settle. In some individuals bowel movements relieve the symptoms. Stools are frequently abnormal, presenting as diarrhoea and/or constipation. IBS is more common in females and in the second to third decades of life. Additional information on IBS is available here.


Intolerance to foods, particularly carbohydrates, are commonly suspected. A diagnosis of such conditions is important in order to restrict or expand a child's diet appropriately and safely. Lactose Intolerance frequently follows gastroenteritis and is usually transient.


There is a geographic/ethnic bias for the development of lactose intolerance - please see map below from Wikipedia website.



Dr Du Toit is able to perform and interpret tests for the diagnosis or exclusion of Celiac disease (gluten sensitivity); if such a test proves positive, the patient is referred to specialist gastroenterology colleagues for confirmation by colonoscopy.



Food allergy and intolerance may play a role in only a few children with constipation. Food allergy could, however be associated with gastroesophageal reflux and colic.


Gastroesophageal Reflux and Gastroesophageal Reflux Disease

When a child has reflux the contents of the stomach and stomach acid regurgitates from the stomach back up into the esophagus. This can result in intense 'heart burn' central pain, which can be extremely distressing to young children. As a consequence of this central pain children may scream and arch their backs at feeding and will find little comfort when lying flat with a full stomach. Vomiting is not always a marked symptoms.

There are many causes of reflux, one of which is food - usually milk - allergy. Dr Du Toit is therefore of the firm belief that allergy testing is warranted, or at the very least, a trial of a hypo-allergenic milk (if not breast fed). For breast fed babies it may be worth trialling select dietary allergen exclusion form the mothers diet.

The final therapeutic step would then be a trail of an antacid such as Ranitidine or Omeprazole. The earlier these steps are taken the better, as untreated reflux results in 'miserable' infants with exhausted parents! Such infants are also at risk of mild anaemia and subsequent fussy eating patterns.

Additional information on GOR and GORD is available here.

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House Dust Mite Allergy

House Dust Mite is a common aero-allergy. HDM-Allergy may present with eczema, asthma and even hayfever; symptoms will usually be of a perennial nature.

The most important house dust mites are Dermatophagoides pteronyssinus and in drier areas D. farinae. In subtropical and tropical regions the glycyphagid mite Blomia tropicalis is a major source of allergen, which co-exists with D. pteronyssinus. Dr Du Toit will tests for allergy to all these mites.

Mite allergy is a problem for many reasons:

  • They are ubiquitous acari (bugs), with allergens that are extremely difficult to eliminate. A reduction in mite allergen is however possible.

  • Allergy develops to the easily aerosolized small mite faecal pellets

  • These pellets contain digestive enzymes that further damage skin/lung linings

Whilst HDM reduction is not guaranteed to switch off your child's symptoms, this is a benign intervention and certainly healthier than the many medications he/she may require to control asthma, eczema and hayfever. Some patients experience a significant improvement in symptoms though mite allergen reduction. If you wish to convince yourself if mite allergy is playing a role book a relaxing holiday in a cold high-altitude resort (as mites will not thrive in such conditions). If an unequivocal improvement is observed then you may wish to strictly follow the steps below when returning home in attempt to reduce indoor mire allergen exposure.

Dr Du Toit also offers Immunotherapy against House Dust Mite

Reduction and treatment of House Dust Mite Allergy:

  • Tips for the reduction of HDM are attached below. Briefly, Dr Du Toit recommends use of the Allerguard bed-covers, hot washing and/or sun exposure of bed linen, removal of dust traps in bedrooms (carpets, minimize fluffy toys), freezing favoured fluffy toys. Acaricides are not effective enough and are potentially dangerous around children.

  • Dr Du Toit does offer Immunotherapy (Sub-lingual or Sub-Cutaneous) against Dust Mite Allergens. Whilst this is not usually as efficacious as Immunotherapy against pollens there is evidence to support its use for asthma, rhinitis and even eczema.

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Hayfever (Alergic Rhino-Conjunctivitis)

Allergic rhino-conjunctivitis affects up to 20% of children and can significantly impair quality of life. 

Rhino-conjunctivitis/hayfever: in allergic rhino-conjunctivitis it is the nose and eyes bear the brunt of the inflammatory reaction; this results in characteristic symptoms such as a blocked or runny nose, repetitive violent sneezing, intense itching of the nose and/or eyes, and a postnasal drip. Mouth breathing results in dry teeth (associated with halitosis and poor dentition) and dry cracked lips which are licked repetitively resulting in a ‘lip licking’ eczema. Sleep patterns may also be disturbed, these children are frequently described as ‘restless sleepers’ as evidenced by chaotic bed linen in the morning. Hayfever can impact on schooling, particularly as exams are usually taken in the summer months. Rubbing of the nose may result in a clear line across the nose (called a nasal crease) and rubbing of the eyes may result in deep skin folds under the eye (called Morgan Denny’s folds); the dark areas under the eyes are called ‘allergic shiners’ - making the children appear fatigued. A post nasal drip may result in a dry hacking cough and ‘antisocial throat clearing noises’ that sometimes drive mothers crazy! Children with hay fever also blink repetitively and distort their itchy mid-facies sometimes resembling the ‘facial mannerisms of a rabbit’ or a nervous tick.

Pollen in UK

Different pollens can cause hay fever at different times of the year. Tree pollens cause hay fever in spring i.e. Feb, March, April months. Grasses are the biggest culprits during mid-summer from May to August. Weeds such as nettles and dock as well as mugwort and plantain can trigger hay fever in late summer and autumn. Birch and alder pollen sensitivity are particular problems for allergy sufferers in the UK (where Birch is increasingly popular); these allergies may give rise to the Oral Allergy Syndrome with increasing age. The main main fungal spore season is in late summer i.e. Sept-Nov. Hay fever is worse in the cities where the symptoms are compounded by pollution. 

Please follow the BBC pollen site in order to anticipate high pollen counts (in anticipation, increased doses of antihistamines can be taken).  The Grass Pollen Mix used in our Skin Prick Test contains cocksfoot, meadow grass, rye-grass, sweet vernal and timothy grass pollen.

Dust Mite

HDM is a perennial allergen that can irritate the surface of the skin, nose and lungs. I recommended the use of bed covers e.g. Allergaurd, hot washing and sun exposure of bed linen, cross ventilation of the bedroom, and reduction of bedroom dust 'traps', e.g. fluffy toys, carpets... Dr Du Toit does not recommend the use of humidifiers or acaricides. Holidays at altitude in cold environments represent an opportunity to assess a clinical improvement in a relative ‘mite free’ environment, possibly justifying the initiation of HDM immunotherapy.

Pet Dander Allergy

Pet allergens, particularly cat and dog, are ubiquitous in urban/school environments in the UK. Allergens originate from the pets hair, dander, pelt, saliva, glands (placed on coat through continual licking and grooming), and serum of the animal. There is great variability in the allergenicity of different breeds, with additional influences depending on hair length, condition of the animal’s skin, age, and sex of the animal. Exposure (esp. in high amounts or in confined spaces) can lead to one or more of hives, itching, eczema exacerbations, rhino-conjunctivitis and wheezing.  If a breed is to be acquired ensure your child has repeatedly tolerated exposure over 3 weeks (allowing time for antibodies to be made) prior to acquiring the pet as this can be an emotive business to deal with as a family.

Dr George Du Toit has extensive experience in the administration of Immunotherapy. This therapy is one of a few potentially curative therapies. SLIT has an excellent safety profile. Please contact the Practice Manager for costs and logistics associated with SLIT.


Allergic conjunctivitis is usually associated with rhinitis and is treated in a similar manner ie with front line medications (such as anti-histamines, eye drops) in conjunction with environmental modification. 

If these measures prove unsuccessful (and a causative trigger is identified) then Sub Lingual Immunotherapy therapy is indicated.

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Latex Allergy

We are able to test for latex allergy by skin prick test and/or specific-IgE blood testing and will then advise on products, cross reactivity and foods that may need to be avoided.

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Preservative, Additive, Colourant Allergy

There are many components added to modern day foods, these include agents to prolong the shelf life, enhance taste and the appearance of foods. Intuitively, these chemical cannot be good for one's health in high amounts.  

Clinical effects of sulphite additives - "Sulphites are widely used as preservative and antioxidant additives in the food and pharmaceutical industries. Topical, oral or parenteral exposure to sulphites has been reported to induce a range of adverse clinical effects in sensitive individuals, ranging from dermatitis, urticaria, flushing, hypotension, abdominal pain and diarrhoea to life-threatening anaphylactic and asthmatic reactions. Exposure to the sulphites arises mainly from the consumption of foods and drinks that contain these additives; however, exposure may also occur through the use of pharmaceutical products, as well as in occupational settings. While contact sensitivity to sulphite additives in topical medications is increasingly being recognized, skin reactions also occur after ingestion of or parenteral exposure to sulphites. Most studies report a 3-10% prevalence of sulphite sensitivity among asthmatic subjects following ingestion of these additives. However, the severity of these reactions varies, and steroid-dependent asthmatics, th ose with marked airway hyperresponsiveness, and children with chronic asthma, appear to be at greater risk. In addition to episodic and acute symptoms, sulphites may also contribute to chronic skin and respiratory symptoms. To date, the mechanisms underlying sulphite sensitivity remain unclear, although a number of potential mechanisms have been proposed. Physicians should be aware of the range of clinical manifestations of sulphite sensitivity, as well as the potential sources of exposure. Minor modifications to diet or behaviour lead to excellent clinical outcomes for sulphite-sensitive individuals." (Vally H, Misso NL, Madan V. 'Clinical effects of sulphite additives' Clin Exp Allergy 2009 Sep 22).

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Pet (Dog, Cat, Horse) Allergy

Pet allergens, particularly cat and dog, are ubiquitous in urban/school environments in the UK. Allergens originate from the pets hair, dander, pelt, saliva, glands (placed on coat through continual licking and grooming), and serum of the animal. There is great variability in the allergenicity of different breeds, with additional influences depending on hair length, condition of the animal’s skin, age, and sex of the animal. Exposure (esp. in high amounts or in confined spaces) can lead to one or more of hives, itching, eczema exacerbations, rhino-conjunctivitis and wheezing.

If a breed is to be acquired ensure your child has repeatedly tolerated exposure over 3 weeks (allowing time for antibodies to be made) prior to acquiring the pet as this can be an emotive business to deal with as a family.

Dr Du Toit does offer Immunotherapy vs select pet danders for select patients i.e. where symptoms significant and the allergen can not easily be avoided through lifestyle changes.

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Insect Sting/Venom Allergy

Insect sting-induced anaphylaxis in the UK is mainly due to bee and wasp stings. In the USA, Asia and Australia it may also be caused by fire ant stings. The severity of the allergic reaction may be varied:

  • mild with local swelling

  • moderate with generalised urticaria

  • severe with systemic symptoms accompanied by wheezing or shock

Dr Du Toit tests for this allergy using specific IgE blood tests and if indicated, desensitisation using immunotherapy will be offered.

Children with a previous mild or moderate reaction are unlikely to develop a severe reaction in future. Those who react severely should carry an epinephrine auto-injector and be desensitised through specific immunotherapy.

Papular Urticaria - Insect Bite/Saliva Sensitivity

Certain individuals are at risk of more severe reactions to insect bites (not stings). This gives rise to local swellings and redness and can prove itchy, uncomfortable and disfiguring. These individuals seem to get bitten far more than others for reasons that remain unclear. Many different insects can result in the same outcome and this arises due to hypersensitivity to the saliva bite. This is more common in childhood but may persist for many years. It often runs in families. Bites are typically more common when families travel on holiday.

Treatment: Only if Dr Du Toit made this diagnosis for you/your child should you follow this approach!

  • To reduce lesions (when travelling or bites noted) please take Vitamin B1 (Thiamine) daily 25 mg; this is available from health stores and is a water soluble (safe) vitamin that is said to decrease bite frequencies.

  • If bitten, use an antihistamine to reduce itching/scratching, and apply a strong steroid ointment on to the bite mark e.g. Elecon Ointment.

  • Barrier protection with nets, long sleeves/trousers and insect repellent sprays should also be used.

  • Antibiotics are of little use (unless obvious signs of cellulitis follow).

  • PU will no result in anaphylaxis (which can occur to insect venom's); patients with PU are at no greater risk of venom allergy.

Further Information

Sting rates in the UK

Insect Stings UK

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Oral Allergy Syndrome (also called Pollen-food Syndrome)

The oral allergy syndrome (OAS) is caused by 'cross-reactivity' between proteins found in fresh foods (fruit, vegetables and nuts) and pollen (usually birch tree and grass pollen in the UK). The OAS is more common among teenagers and adults, but Dr Du Toit is noticing that children are now commonly affected even in their first decade of life. 

The OAS develops subsequent to the development of pollen sensitisation, hence tolerance of these foods is typical when younger. When children then start developing an aversion of these foods this confuses parents and often the aversion is seen as 'fussiness'. Confusing this further for parents and the patient alike is that the foods can be eaten when cooked e.g. Tomato sauce is tolerated but not fresh tomatoes, or apple as apple juice or apple pie. Furthermore, as the majority of the responsible allergens reside in the peel of the fruit, many individuals with OAS will tolerate the fruit when eaten peeled.  

The OAS is unlike a 'classic' food allergy, which develops independent of pollen allergy.  The responsible proteins in the food (fruits and/or vegetables and/or nuts) that cause the OAS symptoms are 'heat-labile' and are therefore easily destroyed by cooking and sometimes by freezing or processing of food. Very few patients outgrow the OAS although the severity of symptoms associated does vary and is typically most troubling during the relevant pollen season. 


Most people with OAS experience mild to moderate intra-oral symptoms, such as a 'metallic' taste, itching, burning and tingling. Occasionally, swelling of the lips, mouth, face, tongue and throat may occur. Symptoms are usually short lived (a few minutes) and rarely progress to anything more serious. Occasionally, in highly-sensitive individuals, gut pain, vomiting, diarrhoea and/or a flare in eczema may be experienced even when the food is eaten cooked. Symptoms are usually more severe during the season in which the responsible pollen is at its height. The allergy specialist only rarely prescribes an injectable adrenaline device for use in the OAS.

Cross reactions have been described for the follwing foods. Importantly not all the foods listed below will cause reactions for any one individual:

  • Birch pollen (common in the UK), including hazelnut, apple, peach, pear, apricot, carrot, celery, cherry, chicory, coriander, fennel, fig, kiwifruit, nectarine, parsley, parsnip, pepper, plum, potato, prune, soy, wheat; Potential reaction: almond nut, and walnut.

  • Alder pollen, including almond, apple, celery, cherry, hazel nut, peach, pear, parsley.

  • Grass pollen (common in the UK), including fig, melon, tomato, orange.

  • Mugwort pollen (more common in USA), including carrot, celery, coriander, fennel, parsley, pepper, sunflower.

  • Ragweed pollen (common in the USA, and increasing in parts of Continental Europe), including banana, cantaloupe, cucumber, honey dew, watermelon, zucchini; Potential reaction: Dandelion or chamomile tea.

  • Possible cross-reactions (to any of the above pollens), including berry (strawberry, blueberry, raspberry, etc), citrus (orange, lemon, etc), grape, mango, fig, peanut, pineapple, pomegranate, watermelon.


  • Awareness and diagnosis of OAS.

  • Avoidance of the offending food, but only in extreme cases.

  • Eating well-cooked, canned, pasteurized or frozen foods, as these cause little or no reaction.

  • Peeling food has shown to reduce the effects of the allergy in the throat and mouth, especially in the case of apples. These measures may not always help prevent/relieve symptoms in the gastrointestinal tract or skin for those who are highly-sensitive.

  • Antihistamines may relieve the symptoms - especially during the pollen season.

  • SLIT (Sub-lingual Allergy Immunotherapy) may improve OAS.

  • Rarely, persons with severe reactions may consider carrying injectable medication, such as an EpiPen, to bring relieve if necessary.

Further Information

UK Anaphylaxis Campaign Information sheet on OAS

Wikipedia Information on OAS

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Vaccines - Adverse Reactions

Adverse reactions to vaccines incorporate both allergic and non-allergic reactions. Millions of routine childhood vaccinations are given every year in the UK. It is reassuring therefore that allergic vaccine-induced reactions are increasingly rare events.

There are however certain conditions that increase the risk for allergic reactions - this comes about due to certain vaccines constituents. If this issue is of concern to you, please make an appointment to discuss this further with Dr George Du Toit.

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