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Allergen immunotherapy Pregnancy: There are no data on the clinical use of ACARIZAX in pregnant women; animal studies do not indicate increased risk to the foetus. Treatment should NOT be initiated during pregnancy. If pregnancy occurs during treatment, treatment may continue after evaluation of the patient's general condition (including lung function) and of reactions to previous administration; close supervision is recommended during pregnancy in patients with pre-existing asthma. Breast-feeding: no clinical data are available, but no effects on breastfed infants are anticipated. Fertility: no clinical data.

House dust mite extracts

Brand names: Acarizax

House dust mite extracts are standardised allergen preparations used for allergen immunotherapy in patients with house-dust-mite-driven allergic rhinitis, and in some products allergic asthma, available as sublingual or subcutaneous formulations.

Adult dose

Dose: SCOPE — SUBLINGUAL ACARIZAX ONLY. House dust mite allergic rhinitis, and allergic asthma in adults: one sublingual lyophilisate (12 SQ-HDM) daily, in patients aged 5-65 years. Subcutaneous house dust mite immunotherapy products and diagnostic skin-test extracts are different preparations and are NOT covered by this source.
Route: Sublingual — take the lyophilisate from the blister with dry fingers immediately after opening and place it under the tongue, where it will disperse. Avoid swallowing for approximately 1 minute; no food or beverage for the following 5 minutes.
Frequency: Once daily
Max: 12 SQ-HDM (one sublingual lyophilisate) once daily — the SPC gives no higher dose and no up-titration or escalation schedule.
Treatment should be initiated by physicians with experience in the treatment of allergic diseases. THE FIRST LYOPHILISATE MUST BE TAKEN UNDER MEDICAL SUPERVISION and the patient monitored for at least half an hour, to enable discussion and possible treatment of any immediate side effects. Onset of clinical effect is expected 8-14 weeks after initiation. International treatment guidelines refer to a treatment period of 3 years for allergy immunotherapy to achieve disease modification; efficacy data are available for 18 months of treatment with ACARIZAX in adults and no data are available for 3 years. If no improvement is observed during the first year of treatment there is no indication for continuing. INTERRUPTIONS: if treatment is interrupted for up to 7 days the patient may resume; if interrupted for more than 7 days, contact a physician before resuming. ELDERLY: there is no clinical experience of immunotherapy with ACARIZAX in adults over 65 years. ASTHMA: ACARIZAX is not intended to treat acute asthma exacerbations — use a short-acting bronchodilator; it should initially be used as add-on therapy and not as a substitute for pre-existing asthma medication, and abrupt discontinuation of asthma controller medication after initiation is not recommended. ORAL CAVITY: postpone initiation, and temporarily interrupt ongoing treatment, in severe oral inflammation, oral wounds, after oral surgery including dental extraction, or after tooth loss, to allow healing. ⚠ SOURCE COMPLETENESS: section 4.2 was retrieved complete, but sections 4.4 and 4.8 are truncated at the source-fetch limit, so the warnings and adverse-reaction lists below are partial. Source product: ACARIZAX 12 SQ-HDM (UK SPC).

Paediatric dose

Dose: One sublingual lyophilisate (12 SQ-HDM) — the label's own paediatric figure, identical to the adult dose and not scaled
Route: Sublingual
Frequency: Once daily
Max: 12 SQ-HDM (one sublingual lyophilisate) once daily — no higher paediatric dose is given
Allergic rhinitis: one sublingual lyophilisate (12 SQ-HDM) once daily — the posology to be used in children aged 5-17 years is the same as in adults. The safety and efficacy of ACARIZAX in children under 5 years of age have not been established and no data are available. Allergic asthma: the efficacy of ACARIZAX in children under 18 years of age has not been established. As with adults, the first lyophilisate must be taken under medical supervision with at least half an hour of monitoring. Verify any under-18 use against a children's formulary.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to any of the excipients listed in section 6.1
  • Patients with FEV1 below 70% of predicted value (after adequate pharmacological treatment) at initiation of treatment
  • Patients who have experienced a severe asthma exacerbation within the last 3 months
  • Patients with active or poorly controlled autoimmune diseases, immune defects, immunodeficiencies, immunosuppression, or malignant neoplastic diseases with current disease relevance
  • Patients with acute severe oral inflammation or oral wounds
  • In patients with asthma experiencing an acute respiratory tract infection, initiation should be postponed until the infection has resolved

Side effects

  • Throat irritation, ear pruritus, lip oedema, mouth oedema, oral pruritus, nasopharyngitis (very common)
  • Mild to moderate local allergic reactions are primarily expected within the first few days, usually starting within 5 minutes of intake and abating after minutes to hours, subsiding with continued treatment over 1-3 months
  • Oropharyngeal pain, pharyngeal oedema, dysphagia, mouth ulceration, glossitis, tongue oedema, oral paraesthesia, stomatitis (common)
  • Asthma, cough, dysphonia, dyspnoea (common)
  • Dysgeusia, eye pruritus, pruritus, urticaria, chest discomfort, fatigue (common)
  • Anaphylactic reaction (uncommon)
  • Throat tightness, nasal oedema, pharyngeal erythema, tonsillar hypertrophy (uncommon)
  • Laryngeal oedema, tracheal oedema, nasal obstruction (rare)
  • Angioedema, eosinophilic oesophagitis (rare)
  • Isolated cases of severe acute worsening of asthma symptoms have been reported

Monitoring

  • Take the first lyophilisate under medical supervision and monitor the patient for at least half an hour
  • Discontinue and contact a physician immediately for severe systemic allergic reactions, severe asthma exacerbation, angioedema, difficulty swallowing, difficulty breathing, changes in voice, hypotension or a feeling of fullness in the throat
  • Advise patients to seek medical attention immediately if asthma deteriorates suddenly, or if a short-acting bronchodilator becomes ineffective or is needed more often than usual
  • One option for treating severe systemic allergic reactions is adrenaline — note its effects may be potentiated by tricyclic antidepressants, MAOIs and/or COMT inhibitors (possible fatal consequences) and reduced by beta-blockers
  • Consider carefully before initiating in patients who have previously had a systemic allergic reaction to subcutaneous house dust mite immunotherapy, and have measures to treat potential reactions available
  • Patients with cardiac disease may be at increased risk in the event of a systemic allergic reaction; clinical experience in this group is limited
  • Reduce asthma controller medication only gradually and under physician supervision, in line with asthma management guidelines

Clinical monograph

How it works

Controlled repeated allergen exposure induces immunological tolerance, modulating allergen-specific T-cell responses and promoting protective blocking IgG antibodies while dampening IgE-mediated reactions.

Prescribing in practice

  • Systemic allergic reactions including anaphylaxis can occur, so treatment must be initiated under specialist supervision with resuscitation facilities available and an appropriate observation period after dosing.
  • Should only be prescribed and supervised by clinicians experienced in allergen immunotherapy after confirmation of clinically relevant mite sensitisation.
  • Use with caution in unstable or severe asthma, which raises the risk of serious systemic reactions; consult the SPC for the individual product.

Monitoring

Monitor for immediate and delayed allergic reactions, with particular vigilance at treatment initiation and dose escalation.

Counselling the patient

  • Mild mouth itching or local swelling is common early in treatment and usually improves over time.
  • Get emergency help for breathlessness, wheeze, widespread rash, or swelling of the face or throat.
  • Treatment is taken regularly over a prolonged period and the full course is needed for lasting benefit.

Evidence & guidelines

Allergen immunotherapy for house dust mite allergy is endorsed by international allergy guidelines, with NICE recognising it for selected patients with severe persistent allergic rhinitis inadequately controlled by conventional treatment.

Reference: BSACI guideline; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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