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Topical antihistamine (H1)

Azelastine

Brand names: Rhinolast (nasal spray), Optilast (eye drops), Dymista (with fluticasone propionate)

Azelastine is a topical second-generation antihistamine available as a nasal spray and eye drops for allergic rhinitis and allergic conjunctivitis.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Allergic rhinitis, intranasal (adults and adolescents 12 years and older): 1 or 2 sprays per nostril twice daily — each spray delivers 137 micrograms of azelastine hydrochloride in 0.137 mL. Vasomotor rhinitis, intranasal (adults and adolescents 12 years and older): 2 sprays per nostril twice daily. Allergic conjunctivitis, ophthalmic: one drop in each eye twice daily, increased if necessary to four times daily (azelastine hydrochloride 0.5 mg/ml eye drops).
Route: Intranasal (allergic and vasomotor rhinitis — the page's primary route) and ophthalmic (allergic conjunctivitis). US label §2.3: 'Administer azelastine hydrochloride nasal spray by the intranasal route only… Avoid spraying azelastine hydrochloride nasal spray into the eyes.' The two products are not interchangeable.
Frequency: Twice daily by either route; the eye drops 'can be increased, if necessary to four times daily' (UK SPC §4.2).
Max: No maximum dose is stated for the nasal route in the fetched labelling — the highest intranasal dosage anywhere in the US label is 2 sprays per nostril twice daily (seasonal allergic rhinitis in adults and adolescents 12 years and older, §2.1; vasomotor rhinitis, §2.2), and no wording such as 'maximum' or 'do not exceed' appears for that route. For the ophthalmic route the upper frequency (four times daily) is already shown in the dose above; what the UK SPC caps is course length, not dose: 'As safety and efficacy have been demonstrated in clinical trials for a period of up to 6 weeks, the duration of any course should be limited to a maximum of 6 weeks.'
VERBATIM US LABEL, NASAL SPRAY — §2.1 Seasonal Allergic Rhinitis: 'The recommended dosage of azelastine hydrochloride nasal spray in adults and adolescent patients 12 years and older with seasonal allergic rhinitis is one or two sprays per nostril twice daily. The recommended dosage of azelastine hydrochloride nasal spray in pediatric patients 5 years to 11 years of age is one spray per nostril twice daily.' §2.2 Vasomotor Rhinitis: 'The recommended dosage of azelastine hydrochloride nasal spray in adults and adolescent patients 12 years and older with vasomotor rhinitis is two sprays per nostril twice daily.' STRENGTH THAT PINS THE SPRAY COUNT (§3): 'Each spray of azelastine hydrochloride nasal spray delivers a volume of 0.137 mL solution containing 137 mcg of azelastine hydrochloride.' PRIMING (§2.3): 'Prime azelastine hydrochloride nasal spray before initial use by releasing 4 sprays or until a fine mist appears. When azelastine hydrochloride nasal spray has not been used for 3 or more days, reprime with 2 sprays or until a fine mist appears.' VERBATIM UK SPC §4.2, EYE DROPS — Seasonal allergic conjunctivitis: 'The usual dosage in adults and children 4 years and older is one drop in each eye twice daily that can be increased, if necessary to four times daily. If allergen exposure is anticipated Azelastine hydrochloride Eye drops, solution should be administered prophylactically, prior to the exposure.' Non-seasonal (perennial) allergic conjunctivitis: 'The usual dosage in adults and children 12 years and older is one drop in each eye twice daily that can be increased, if necessary to four times daily. As safety and efficacy have been demonstrated in clinical trials for a period of up to 6 weeks, the duration of any course should be limited to a maximum of 6 weeks. Patients should be advised to contact their doctor if symptoms worsen or do not improve after 48 hours.' EYE DROPS — NOT FOR INFECTION (§4.4): 'Azelastine hydrochloride Eye drops, solution is not intended for treatment of eye infections.' CONTACT LENSES (§4.4): the drops contain benzalkonium chloride, which 'may cause eye irritation, especially with dry eyes or disorders of the cornea. Contact with soft contact lenses should be avoided. Contact lenses should be removed prior to application and the patient should wait at least 15 minutes before reinsertion. Known to discolour soft contact lenses.' SYSTEMIC EXPOSURE (§4.5, eye drops): 'No specific interaction studies have been performed. Interaction studies at high oral doses of Azelastine have been performed however they bear no relevance to Azelastine hydrochloride Eye drops, solution, as systemic levels, after administration of the eye drops, are in the picogram range.' UK/US DIFFERENCE TO CHECK: the UK nasal product's strength per spray is not in this bundle and is not necessarily 137 micrograms — do not transfer the microgram figure above to a UK nasal product without checking its SPC.

Paediatric dose

Route: Intranasal (allergic rhinitis) / ophthalmic (allergic conjunctivitis)
Frequency: Twice daily; the eye drops can be increased if necessary to four times daily
Not weight-based — these are fixed spray and drop counts, so no per-kg figure exists and the weight calculator is deliberately left unset. NASAL (US label §2.1, verbatim): 'The recommended dosage of azelastine hydrochloride nasal spray in pediatric patients 5 years to 11 years of age is one spray per nostril twice daily'; patients 12 years and older are dosed as adults ('one or two sprays per nostril twice daily'). Each spray delivers 137 micrograms of azelastine hydrochloride in 0.137 mL (§3). The US label gives no nasal dosage below 5 years, and no vasomotor-rhinitis dosage below 12 years. OPHTHALMIC (UK SPC §4.2, verbatim): seasonal allergic conjunctivitis — 'The usual dosage in adults and children 4 years and older is one drop in each eye twice daily that can be increased, if necessary to four times daily'; non-seasonal (perennial) allergic conjunctivitis — 'The usual dosage in adults and children 12 years and older is one drop in each eye twice daily…'. The SPC gives no ophthalmic dose below 4 years, and none below 12 years for the perennial indication; course length is limited to a maximum of 6 weeks. No UK nasal-spray SPC was in this bundle, so the UK nasal product's strength and licensed lower age limit must be confirmed against its own SPC and a children's formulary before prescribing.

Dose adjustments

Renal

Not stated. Neither the UK eye-drops SPC nor the US nasal-spray label contains any renal dosing statement in the fetched sections (the UK §4.2 has no special-population dosing at all). UK §4.5 notes that after ocular administration 'systemic levels… are in the picogram range'.

Hepatic

Not stated. Neither fetched label contains a hepatic dosing statement (the UK eye-drops §4.2 has no special-population dosing at all). UK §4.5 notes that systemic levels after ocular administration are in the picogram range.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1 — the only contraindication in UK SPC §4.3 for the eye drops. The US nasal-spray label §4 states 'None.'
  • Not a contraindication but a limit of what is licensed/dosed: the fetched labelling gives no ophthalmic dose below 4 years of age (and none below 12 years for perennial allergic conjunctivitis), and no nasal dose below 5 years of age
  • Not a contraindication but a §4.4 warning: 'Azelastine hydrochloride Eye drops, solution is not intended for treatment of eye infections'
  • Not a contraindication but a §4.4 warning: the eye drops contain benzalkonium chloride — avoid contact with soft contact lenses, remove lenses before instillation and wait at least 15 minutes before reinsertion
  • Not a contraindication but a US §5.1/§7.1 warning for the nasal spray: avoid concurrent alcohol or other central nervous system depressants, 'because further decreased alertness and impairment of CNS performance may occur'

Side effects

  • Eye drops, common (≥1/100 to <1/10): mild, transient irritation in the eye (UK §4.8)
  • Eye drops, uncommon (≥1/1,000 to <1/100): bitter taste (UK §4.8)
  • Eye drops, very rare (<1/10,000): allergic reactions such as rash and pruritus (UK §4.8)
  • Nasal spray, most common adverse reactions at ≥2% incidence (US §6): bitter taste, headache, somnolence, dysesthesia, rhinitis, nasal burning, pharyngitis, epistaxis, sinusitis, paroxysmal sneezing, nausea, dry mouth, fatigue, dizziness and weight increase
  • Nasal spray, US §5.1: 'the occurrence of somnolence has been reported in some patients taking azelastine hydrochloride nasal spray' — patients 'should be cautioned against engaging in hazardous occupations requiring complete mental alertness and motor coordination such as operating machinery or driving a motor vehicle after administration'
  • The US §6.1 clinical-trials narrative is truncated at the source-fetch limit, so the nasal list above is incomplete

Monitoring

  • Review if symptoms do not settle — UK SPC §4.2 (eye drops): 'Patients should be advised to contact their doctor if symptoms worsen or do not improve after 48 hours'
  • Course length for the eye drops — UK §4.2: 'the duration of any course should be limited to a maximum of 6 weeks' (safety and efficacy were demonstrated in clinical trials for up to 6 weeks)
  • Contact lens wearers — UK §4.4: remove lenses before instillation and wait at least 15 minutes before reinsertion; the drops are 'known to discolour soft contact lenses'
  • Sedation with the nasal spray — US §5.1: warn against driving or operating machinery, and avoid alcohol and other CNS depressants
  • Device check for the nasal spray — US §2.3: prime with 4 sprays before first use, and re-prime with 2 sprays when it has not been used for 3 or more days
  • No laboratory monitoring is specified in any fetched section of either label

Clinical monograph

How it works

It selectively antagonises histamine H1 receptors and also has mast-cell stabilising and anti-inflammatory properties at the site of application.

Prescribing in practice

  • Patients may notice a transient bitter taste after nasal use, which can reduce adherence and is minimised by correct head-forward technique.
  • Onset of action is rapid, making it suitable for as-needed use in allergic symptoms.
  • It is also combined with a topical corticosteroid in some nasal preparations for more troublesome rhinitis.

Monitoring

No laboratory monitoring is required; review symptom control and local tolerability.

Counselling the patient

  • Tilt the head slightly forward and breathe gently when spraying to reduce taste in the throat.
  • A bitter taste shortly after use is common and harmless.
  • Use regularly during the allergy season for best effect.

Evidence & guidelines

Topical antihistamines are recommended options for allergic rhinitis and conjunctivitis in NICE guidance.

Reference: SmPC Rhinolast / Optilast / Dymista; BSACI Rhinitis Guideline 2017; MP4002 trial Berger et al. AAAI 2016; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). 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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