Referral Guidelines for Allergy in General Practice

Allergy in 10 minutes DETECTIVE WORK Presenting episode Previous episodes Consistent trigger or pattern to episodes Contacts/Foods in previous 4 hours (most begin within 30 minutes) Co-factors - exercise/alcohol/NSAIDS/intercurrent illness Other drugs Atopic medical history - CONCURRENT ASTHMA Assess severity

GRADING SYSTEM FOR GENERALISED HYPERSENSITIVITY REACTIONS GRADE Brown et al 2006 1 MILD Skin and subcutaneous tissues only: Generalised erythema, urticaria, periorbital oedema or angioedema 2 MODERATE Respiratory, cardiovascular or gastrointestinal symptoms: Dyspnoea, stridor, hoarseness, wheeze Nausea, vomiting Dizziness (presyncope), diaphoresis Chest or throat tightness, abdominal pain 3 SEVERE Hypoxia, hypotension or neurological compromise: Cyanosis or SpO2≤92% Systolic blood pressure<90mmHg in adults Confusion, collapse, loss of consciousness

Management of Anaphylaxis RESCUE KIT: MILD: Anti-histamine high dose MODERATE: ADD Soluble prednisolone 30mg (0.5mg/kg) SEVERE: ADD Adrenaline auto injector 300mcg/500mcg over 30kg 150mcg 15-30kg

Anaphylaxis Refer suspected severe anaphylaxis symptoms: Any combination of: Bronchospasm Laryngeal/pharyngeal oedema Hypotension USUALLY with flushing, urticaria, angioedema If blood sample taken: Gold top marked: ‘HOLD- allergens to be advised’

Urticaria & Angioedema Non –allergic cause suggested if: Spontaneous/overnight/early morning Physical triggers Several days duration No consistent relationship with food (ingestion/contact) In Food Allergy: Symptoms usually within 30 minutes of ingestion Delay of more than 2 hours is rare ACE-I with angioedema

Lots of guidelines…

Definition Urticaria Wheals Mediated by histamine ‘Hives’ ‘Nettle rash’ Wheals Central swelling of variable size with reflex erythema Associated with itching (or sometimes burning) Fleeting nature, lasting 1 – 24 hours Mediated by histamine

Definition Angioedema Mediated by bradykinin (also histamine) Sudden, pronounced erythematous or skin-coloured swelling of lower dermis, subcutis and below mucous membranes Sometimes pain rather than itching Slower resolution, up to 72 hours Mediated by bradykinin (also histamine)

Treatment: Angioedema with or without urticaria Rx as for urticaria Check not on ACE-I Isolated angioedema: check C3, C4, C1-inhibitor and electrophoresis If intraoral swelling: Add soluble prednisolone 30mg as stat PRN dose Consider need for adrenaline auto-injector REFER

Epidemiology Common – lifetime incidence of urticaria is 20% 30% of these go on to experience prolonged symptoms Can occur at any age 40% urticaria only 50% urticaria and angioedema 10% angioedema only

Quality of life issues Can significantly affect QOL Affects both objective functioning and subjective well-being Work Education Social aspects Comparable health status scores to patients with coronary artery disease Guidelines recommend objective QOL measures

Classification Acute <6 weeks Chronic >6 weeks Spontaneous Triggers Allergy Medication e.g. NSAIDs, oestrogens Infections Chronic >6 weeks

Classification of chronic urticarias Chronic spontaneous urticaria Previously ‘idiopathic’ or ‘ordinary’ urticaria Stimuli mostly unknown NOT allergy Chronic inducible urticarias Symptomatic dermographism Cold urticaria Pressure urticaria Solar urticaria Heat urticaria Vibratory angioedema Cholinergic urticaria Aquagenic urticaria Contact urticaria

Diagnosis History is very important

Investigations Acute spontaneous urticaria No routine diagnostic tests recommended Extended testing only if strong suggestion from history e.g. allergy Chronic spontaneous urticaria Routine: FBC, ESR or CRP Omit suspected drugs (e.g. NSAIDs) Extended testing based on history Infectious disease, Type I allergy, TFTs and thyroid antibodies, skin tests, low pseudoallergen diet, tryptase, skin biopsy, autoantibodies against IgE receptor, ANA, complement Inducible urticarias Physical provocation tests e.g. ice cube test for cold urticaria

Management Aim of treatment is complete symptom relief as safely as possible 2nd generation antihistamines cetirizine, loratadine, fexofenadine (desloratadine, levocetirzine, rupatadine, bilastine) Short course of steroids (up to 10 days maximum) for acute urticaria or acute exacerbations Long term treatment not recommended Same treatment algorithm for children Acute urticaria is self-limiting Need for treatment may vary with time (step up step down)

Management Avoidance of triggers Medication Physical factors (for inducible urticaria) Dietary manipulation Food allergy is very rare Patients with known food sensitisation should only avoid if there is clear history or relevant test e.g. food challenge to show that it is relevant to urticaria Low pseudoallergen diets Limited evidence Recommended by European guidelines, but not in American guidelines Long list of medicines with little evidence have been tried H2 antihistamines (although recommended in American guidelines) Nifedipine Warfarin Dapsone Hydroxychloroquine Sulfasalazine Methotrexate Mycofenolate Colchicine IVIG Azathioprine

Interactions with other medicines First-generation antihistamines Alcohol Night sedatives Benzodiazepines Tricyclic antidepressants Monoamine oxidase inhibitors Second-generation antihistamines Most second-generation antihistamines do not have important interactions Rupatadine  - antibiotics (minocyclines) or grapefruit juice Mizolastine  - nifedipine , cimetidine  and ciclosporin  Third generation Fexofenadine ketoconazole erythromycin

Side effects First-generation antihistamines Common: drowsiness (should not be underestimated) dry mouth dizziness constipation blurred vision urinary retention Less common: insomnia  nightmares hallucinations itchy skin Rare: palpitations chest tightness

Side effects Second-generation antihistamines Less common: (usually pass) drowsiness headache dry mouth dry nose Rare: palpitations chest tightness Third-generation antihistamines Similar to second-generation drowsiness (less common than with first-generation antihistamines) nausea Do not carry the same risk of arrhythmia

Low pseudoallergen diet Diet needs to be followed for 3 weeks

Management of isolated angioedema ‘Idiopathic’ ACE inhibitors Should be stopped Can cause angioedema Can worsen angioedema due to other causes Occurs even after a few years on medication Can take several months for effect to wear off even after stopping medication ARBs can be used in place if needed Small chance of swelling with ARB as well C1 inhibitor deficiency Hereditary angioedema (HAE) Acquired angioedema Very rare Low C4 Reduced C1 inhibitor levels and/or function

Summary Urticaria/angioedema is common Can have profound impact on quality of life Acute urticaria rarely needs investigating unless suggested by history Chronic urticaria is almost never due to allergy Usually chronic spontaneous, or inducible Aim of treatment is complete symptom relief - NO wheals, swelling or itch First line treatment is 2nd generation antihistamines Standard dose, can be increased up to 4x Stop ACE inhibitors in angioedema

Hay fever Start 2 weeks prior to earliest symptoms Continue daily treatment throughout season ‘Itchy –Sneezies’: Potent antihistamine up to 2 bd Nasal congestion: Intranasal Steroids up to 2 bd Ocular symptoms: opticrom/optilast Consider montelukast REFER: Rescue steroids/SLIT/IT

Eczema in Adults Adult patients often keen to find a dietary allergic cause Many demonstrate apparent sensitisation Routine blood testing not advised in the absence of symptoms of food allergy Contact eczema: Skin PATCH testing- Dermatology

SUMMARY: When to Refer Insect venom anaphylaxis Symptoms do not respond to treatment/avoidance Confirmed IgE mediated food allergy with asthma Tests are negative but a strong suspicion of allergy Anaphylaxis of uncertain cause Review of condition/for retesting/management