SCA Revision Guide: Allergy & Immunology

Allergic disease already occupies a hefty slice of everyday general practice, but in adults and children, with prevalence continuing to climb. With the SCA spotlight firmly trained on patient-centred consultations that test clinical reasoning and your ability to safety-net, Allergy & Clinical Immunology is a guaranteed fixture. There might be whole SCA cases on it, or it might make up a small but important part of an unrelated case.

For example, did you ask about a patient’s allergies before prescribing that antibiotic?

Let’s dive into this hot topic and see why a good grasp of allergy is important in order to do well in your exam:

• Frequency – The UK still leads European league tables for asthma, rhinitis and eczema presentations, meaning you will see allergic scenarios in surgery and in the exam.
• Risk-stratification – Missing anaphylaxis or mislabelling a drug allergy (or forgetting to ask and prescribing the wrong antibiotic or other medication) has immediate safety consequences that examiners love to probe.
• Societal narrative – Climate-related extensions of the pollen season and widening food allergen exposure keep allergy in headlines and consultations alike. 

8 Allergy Related Hot Topics

These are both a refresher for your SCA exam and helpful in clinical practice.

1. Anaphylaxis: recognise early, treat fast

• IM adrenaline remains first-line – 500 µg (0.5 mL of 1:1 000) for adults, repeat after 5 min if ABC compromise persists.
• Common pitfalls tested in SCA: delayed adrenaline, chasing IV access, or forgetting to dial 999 after community treatment. Although there are no practical scenarios, you may be asked to explain to a patient how to use adrenaline or walk them through anaphylaxis, help them recognise it and advise what they should do.
• Communication pearl – Check the patient understands device technique; you can use the “teach back” technique for this and other similar cases to check patient understanding.
• Follow-up after episode of anaphylaxis – Issue two auto-injectors, arrange same-day steroid/antihistamine scripts and an allergy clinic referral.

2. Drug allergy labelling & de-labelling

• Around 10 % of patients report a penicillin allergy, but < 1 % are truly allergic; mislabelling drives broad-spectrum use and AMR, but is often unavoidable. The waiting lists for penicillin allergy testing can be massive as this is often only done in hospitals rather than private clinics due to the high risk.
• Make sure you understand mechanisms (Type I-IV) and local β-lactam de-labelling pathways.
• SCA roleplays often centres on reassurance, shared decision-making and discussing supervised oral challenges, which is what an allergy specialist might do once the patient is seen in their allergy clinic after a potential reaction.

3. Atopy triad: asthma, eczema and allergic rhinitis

• Examiners like multi-system consultations: e.g. a teenager with poorly controlled asthma whose hay fever flares every June.
• Integrated management – Optimise preventer inhaler technique, introduce daily non-sedating antihistamines (Cetirizine, Loratadine, Fexofenadine), consider topical steroids for dermatitis, and flag relevant peak-flow diaries for escalation criteria.
• Link pollen counts to flare-ups and be able to give a few tips on how to decrease pollen count indoors or advise to avoid high pollen count days. 

4. Food allergy: IgE vs non-IgE

• Red flags for IgE-mediated reactions include rapid-onset urticaria, lip swelling, wheeze or collapse – cue adrenaline kit and referral.
• Non-IgE (e.g. delayed CMPA most common in infants) often manifests as colic, loose stools or failure to thrive/ vomiting; managed with exclusion and dietitian input.
• Be ready to explain Pollen Food Syndrome (birch–apple cross-reactivity) and how climate change lengthens birch seasons.

5. Urticaria & angio-oedema

• Most chronic spontaneous urticaria (CSU) is non-allergic;
• Patients will need to be reassured, avoid unnecessary tests, and step-up non-sedating antihistamines to a quadruple dose before considering omalizumab. Of course, Omalizumab will only be started after an allergy specialist consultation.
• Simple IgE testing may still need to be done to rule out other potential causes, but this will depend on the scenario. Is the patient pushing for an allergy test and your gut instinct is telling you that you shouldn’t do it? Then perhaps the SCA case is testing you on the ability to reassure the patient without the need to order tests that you think are unnecessary in order to guide clinical management.
• Ask yourself: Would the clinical management change if I do this test?

6. Venom allergy & immunotherapy

• Key revision point: refer after a systemic reaction to bee/wasp stings; immunotherapy cuts future severity by > 90 % and is very effective. Currently, immunotherapy for allergies is done through subcutaneous injections.
• SCA stations often revolve around risk-mitigation: carrying pens, gardening precautions, and driving advice post-stings.

7. Vaccination & immune modulation

• Hot post-pandemic line: COVID-19 vaccine guidance for high-risk allergy patients (previous PEG reactions, mastocytosis).
• Broaden scope to HBV serology interpretation (e.g. non-responders), post-transplant immunisation schedules and travel vaccines in immunocompromised hosts. You are unlikely to be asked the schedules but you may need to provide some general advice on travel vaccinations.
• Bring prescriptions alive: safe steroid dosing in eczema, nasal steroids for rhinitis, correct spacer use. Explain about the FTU (Finger Tip Unit) and how to use this depending on where the eczema is.

8. Climate change & the allergy landscape

• Longer pollen seasons and higher allergen potency escalate rhinitis and asthma morbidity. Like it or not, the RCGP wants you to be aware of potential changes in prevalence and severity related to climate change.
• Air pollution intensifies birch allergen Bet v 1 concentrations and can also raise Pollen Food Syndrome prevalence. 
• Emerging UK public-health alerts include thunderstorm asthma surges and potential mosquito-borne disease encroachment. 
  • Thunderstorm asthma happens when the humidity preceding a thunderstorm can make an asthma episode flare up. It’s now recognised as a potential risk factors.
• Practical SCA angle: discuss environmental triggers, apps for pollen forecasts, and nasal saline irrigation as non-pharmacological adjuncts. If you do advise nasal saline irrigation to someone, ensure that you emphasize the need to use sterile water or distilled water, and not tap water (unless of course they boil it first).

So there you go, this is a quick summary of the hot topics in allergy and clinical immunology. Our SCA AI Tutor is well trained around all these topics, so have a chat with it for further clarification or more tips!