Urticaria and or angioedema

For the patient to receive the most accurate and timely review, photographs at the time of referral will speed up advice provided and aim to exclude alternative diagnoses. Whilst this is not mandatory, it is encouraged.

Referral Criteria

Urgent referral criteria

  • Patients experiencing life-threatening symptoms, severe anaphylactoid-type reactions or atypical urticarial lesions e.g. urticarial vasculitis. *
  • Patients experiencing life-threatening laryngeal episodes and are not on an ACE inhibitor
  • Pregnant or lactating women where it is unadvisable to go above licenced doses of antihistamines
  • Persistently raised mast cell tryptase
  • Angioedema in isolation with a low C4

*Urticarial vasculitis Is typically characterised by wheals which last from days to weeks, leave hyperpigmentation/scarring and the presence of constitutional symptoms such as arthralgia and fever

*If there is uncertainty as to whether the lesions are urticarial, advice and guidance on photographs should be sought.

Routine referral

  • Chronic Spontaneous Urticaria +/- angioedema– refractory to standard treatment
  • Angioedema in isolation – refractory to standard treatment

Not to refer

  • Isolated/intermittent episodes of urticaria not associated with food ingestion i.e. at least 2 hours after food
  • Pruritis in isolation without a rash
  • Generalised body swelling – this is not angioedema

Background

Urticaria (also known as nettle rash or hives) is an itchy, erythematous, elevated, well defined and irregularly shaped rash that can occur anywhere on the body and may last from only a few minutes up to twenty-four hours. Rashes with features of blistering, desquamation of the skin or with individual lesions lasting longer than 24 hours are not urticarial and an alternative diagnosis needs to be considered. A dermatology referral may be considered in these circumstances. We do not accept patients affected by pruritis (and no rash) and eczema.

Angioedema is usually (but not always) histamine mediated, in such cases it is usually responsive to antihistamine therapy and is managed like chronic urticaria. In a minority of cases, it may be bradykinin mediated.

Acute urticaria

Only a fraction of acute urticaria is due to a food allergy. Single episodes of urticaria may be the manifestation of a food allergy if there is a clear history of ingestion of an implicated food. More commonly it results from intercurrent viral infection, drug ingestion, particularly with non-steroidal anti-inflammatory drugs or is completely idiopathic. Non-recurring episodes of urticaria are highly unlikely to be due to any type of allergy and the patient should be reassured about this.

An isolated episode of urticaria that has occurred one hour after food ingestion does NOT need to be referred. Patients should be advised regarding antihistamine use. They can be advised to use antihistamines above the licensed dose (see chronic urticaria guidelines) as needed.

Patients should be directed to the following website which provides up to date patient information:

Urticaria and Angioedema | Allergy UK | National Charity

Chronic Spontaneous Urticaria (CSU)

Urticaria which last longer than six weeks is termed chronic spontaneous urticaria, patients should be directed to Urticaria and Angioedema | Allergy UK | National Charity and should be advised that testing for multiple allergies is not going to be of benefit.

Common triggers for chronic urticaria include:

  • Viral infections
  • Non-steroidal anti-inflammatory drugs, including over the counter medication
  • Physical stimuli such as pressure on the skin or changes in temperature
  • Stress
  • Additives, preservatives and colourants

Chronic urticaria management in primary care

  • NSAIDs such as Aspirin, Naproxen, Diclofenac, Mefenamic acid and Ibuprofen can exacerbate the condition and therefore should be avoided.

  • Pharmacological treatment at this stage consists of appropriate use of antihistamines. We recommend using a licensed dose of non-sedating 2nd or 3rd generation antihistamines, for example Loratadine or Cetirizine 10 mg daily. If symptoms persist more than 2 weeks, we would recommend increasing the dose of antihistamines up to 4-times the licensed dose. We generally use either Cetirizine/Loratadine at a dose of up to 40mg daily (20mg BD), or Fexofenadine at a dose of up to 720mg daily (360mg BD) as per British Society of Allergy and Clinical Immunology (BSACI) guidelines.

  • If antihistamine treatment has failed, please check haemoglobin, CRP, LFTs, thyroid function, calcium & vitamin D, folate, B12 and ferritin levels. We know that disturbances in any of these can cause or exacerbate disease. You should aim for a ferritin >25 mcg/ml even if not anaemic and treat a vitamin D <70 nmol/l with high dose Colecalciferol as per local guidelines.

  • In 80% of patients CSU will go into remission after 6 months, antihistamines can be titrated according to treatment response.

  • Referrals where the advice above has not been followed will be rejected.

  • If the patient is taking four times a day antihistamine and blood tests have been checked and corrected if applicable, and the patient is still having urticaria, please refer to our service.

  • You may also consider adding montelukast 10mg at night.

Cold/heat induced urticaria, solar urticaria and cholinergic urticaria should be managed in the same way as CSU.

The chronic spontaneous urticaria pathway is led by a highly advanced Clinical Pharmacist and senior nurses.  Including photographs of the patient’s rash is extremely helpful and will ensure more accurate triaging and early advice. From July 2025 we will be implementing a new virtual CSU pathway by which patients will be asked to send through photos of their rash and Urticaria Activity Scores.

Angioedema in association with urticaria

Where angioedema occurs in association with urticaria, the management is the same as the mechanism is likely to be histamine mediated. Consider prescribing an adrenaline autoinjector if there is tongue or throat swelling, these cases should be referred on a routine basis.

Useful resources

Patients may find the following websites useful:

British Association of Dermatologists (bad.org.uk) Urticaria and Angioedema | Allergy UK | National Charity

Angioedema in isolation on an angiotensin converting enzyme inhibitor (ACEi)

The most common cause of angioedema in isolation is ACEi use, it can occur a number of years after being on the drug. Where a patient is on an ACEi please follow the following advice.

  • Stop the ACE inhibitor.
  • An adverse reaction to ACE inhibitors should be recorded in their drug sensitivities section. Angiotensin II receptor blockers which have less propensity to cause angioedema may be used as an alternative if necessary.
  • Angioedema due to ACE inhibitors can continue for a number of months after the drug is stopped. High dose antihistamines such as Cetirizine/Loratadine up to 20mg BD or Fexofenadine up to 360mg BD can be used regularly for symptom control if required.
  • We would advise that the patient is reviewed 3 months after the drug is stopped, if at this point they continue to have episodes of angioedema please refer them to the Allergy Clinic.

Angioedema in isolation not on an ACEi

The same advice as CSU applies. However, to exclude hereditary angioedema please send a C3 and a C4 with “angioedema” in the clinical details. In cases where the C4 is low please make an urgent referral so that C1 esterase inhibitor deficiency can excluded.

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