Omalizumab (Dermatology — Chronic Urticaria)

How it works

It binds free immunoglobulin E and lowers its availability to bind mast cells and basophils, reducing the IgE-mediated mast-cell activation that drives the weals and angioedema of chronic urticaria.

Prescribing in practice

• Anaphylaxis can occur with omalizumab, so administer where resuscitation facilities are available and observe the patient after injection.
• It controls symptoms rather than curing the disease, and urticaria may recur after stopping, so review ongoing need.
• Given by subcutaneous injection at intervals; it is an add-on once antihistamine therapy has been optimised.

Monitoring

Monitoring is clinical, using urticaria activity and itch scores to assess response and observing for hypersensitivity reactions around dosing.

Counselling the patient

• This treats the symptoms of hives; they may return if treatment is stopped.
• Seek emergency help for any signs of a severe allergic reaction such as breathing difficulty or facial swelling.
• Continue your antihistamines as advised while on this injection.

Evidence & guidelines

Omalizumab is recommended by NICE for chronic spontaneous urticaria inadequately controlled by antihistamines, supported by the ASTERIA and GLACIAL trials.