Ophthalmic H1 antihistamine + mast cell stabiliser

Epinastine hydrochloride

Brand names: Relestat

Epinastine is a topical ocular antihistamine and mast cell stabiliser used to prevent and relieve the itching of 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: One drop in each eye

Route: Topical ophthalmic (eye drops, solution 0.5 mg/mL)

Frequency: Twice a day

NO UK SPC WAS FETCHED — dose taken from the US FDA prescribing information for EPINASTINE HYDROCHLORIDE ophthalmic solution (Somerset Therapeutics, label date 2025-03-22); verify against the UK SPC. §2: 'The recommended dosage is one drop in each eye twice a day. Treatment should be continued throughout the period of exposure (i.e., until the pollen season is over or until exposure to the offending allergen is terminated), even when symptoms are absent.' Strength (§3): ophthalmic solution containing 0.5 mg/mL epinastine HCl. Paediatric (§8.4): 'Safety and effectiveness in pediatric patients below the age of 2 years have not been established' — no per-kg paediatric dose is given. Geriatric (§8.5): no overall differences in safety or effectiveness between elderly and younger patients. For topical ophthalmic use only — not for injection or oral use. Do not use to treat contact lens-related irritation; patients should not wear a contact lens if the eye is red; the benzalkonium chloride preservative may be absorbed by soft contact lenses, so remove lenses before instillation and reinsert after 10 minutes. To minimise contamination, do not touch the dropper tip to any surface and keep the bottle tightly closed when not in use.

Dose auto-extracted from 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

None (US label §4 states 'None')

Side effects

Ocular (approximately 1% to 10%): burning sensation in the eye
Ocular (approximately 1% to 10%): folliculosis
Ocular (approximately 1% to 10%): hyperaemia
Ocular (approximately 1% to 10%): pruritus
Non-ocular: infection (cold symptoms and upper respiratory infections) in approximately 10%; headache, rhinitis, sinusitis, increased cough and pharyngitis in approximately 1 to 3%

Clinical monograph

How it works

It selectively antagonises histamine H1 receptors and stabilises mast cells, reducing histamine release and the ocular signs and symptoms of allergic conjunctivitis.

Prescribing in practice

It is for ocular use only and should not be used to treat contact lens-related irritation; lenses should be removed before instillation and reinserted only after an appropriate interval.
It is intended to prevent and relieve allergic eye symptoms rather than treat ocular infection, and persistent or worsening symptoms warrant review.
Mild transient ocular discomfort or burning can occur on instillation.

Monitoring

Routine laboratory monitoring is not required; review symptom control and ocular tolerance.

Counselling the patient

Remove contact lenses before using the drops and wait as advised before reinserting them.
Use regularly during the allergy season for best effect.
Report any worsening redness, pain or discharge, which may suggest infection.

Evidence & guidelines

Dual-acting topical antihistamine/mast cell stabilisers are well established for allergic conjunctivitis, with use guided by the SPC.

Reference: RCOphth; BSACI; SmPC; 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).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways