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Alpha-1 Adrenergic Agonist — Mydriatic Pregnancy: §4.6, verbatim: 'Safety for use in pregnancy and lactation has not been established. This product should only be used during pregnancy if it is considered by the physician to be essential.'

Phenylephrine Eye Drops 2.5% / 10%

Brand names: Minims Phenylephrine

Phenylephrine eye drops are a topical sympathomimetic mydriatic used to dilate the pupil for ophthalmic examination and procedures and, at lower concentrations, to relieve minor ocular redness.

Adult dose

Dose: Mydriasis — to dilate the pupil in diagnostic or therapeutic procedures. SCOPE: this dose is for PHENYLEPHRINE 10% eye drops only (Minims Phenylephrine Hydrochloride 10% w/v); no source for the 2.5% strength also named on this page is present in this bundle, and the 2.5% strength is not covered by anything below. Adults: apply one drop to each eye. If necessary, this dose may be repeated ONCE only, at least one hour after the first drop. Phenylephrine 10% is contraindicated in children under 12 years and in the elderly, so this dose applies to non-elderly adults only.
Route: Topical (ophthalmic) — one drop instilled into each eye. Method of administration (§4.2, verbatim): 'The use of a drop of topical anaesthetic a few minutes before instillation of phenylephrine is recommended to prevent stinging.'
Frequency: Single application. §4.2, verbatim: 'If necessary, this dose may be repeated once only, at least one hour after the first drop.'
Max: Two drops per eye in total for phenylephrine 10%: the initial drop plus at most ONE repeat, given at least one hour after the first drop. §4.2 states no further ceiling for this indication.
LICENSED INDICATION (§4.1, verbatim): 'Phenylephrine is a directly acting sympathomimetic agent used topically in the eye as a mydriatic. It may be indicated to dilate the pupil in diagnostic or therapeutic procedures.' This matches the page's primary indication, route and population, so the dose is published — but only for the 10% strength. TWO-STRENGTH PAGE — READ THIS BEFORE USING THE FIELDS BELOW: the page is titled 'Phenylephrine Eye Drops 2.5% / 10%'. Every dose, contraindication and warning on this draft comes from the 10% SPC and each 10%-specific restriction has been tagged with its strength so that it cannot be read as applying to 2.5%. A previous review held this page because those restrictions ('children under 12', 'the elderly') rendered as unqualified page-level facts; the SPC states both of them strength-tagged itself ('Phenylephrine 10% is contraindicated in children aged below 12 years'; 'The use of phenylephrine 10% solution is contraindicated in this group because of the increased risks of systemic toxicity'), and that tagging is preserved here. To remove the limitation entirely, source the eMC SPC for the 2.5% w/v Minims presentation, or split the page into separate 2.5% and 10% monographs. POPULATION LIMITS (§4.2, verbatim): 'Phenylephrine 10% is contraindicated in children aged below 12 years (see section 4.3). There is no data in children aged 12 to 18 years. Phenylephrine is not recommended in these patients.' 'The use of phenylephrine 10% solution is contraindicated in this group [the elderly] because of the increased risks of systemic toxicity.' REDUCING SYSTEMIC ABSORPTION (§4.4, verbatim): 'Systemic absorption may be minimised by compressing the lacrimal sac at the medial canthus for one minute during and after the instillation of the drops. This blocks the passage of the drops via the naso-lacrimal duct to the wide absorptive area of the nasal and pharyngeal mucosa.' Also: 'Ocular hyperaemia can increase the absorption of phenylephrine given topically', and 'Corneal clouding may occur if phenylephrine 10% is instilled when the corneal epithelium has been denuded or damaged.' BEFORE USE (§4.4): 'To reduce the risk of precipitating an attack of narrow angle glaucoma evaluate the anterior chamber angle before use.' CAUTION (§4.4): 'Use with caution in the presence of diabetes, cerebral arteriosclerosis or long standing bronchial asthma.'

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

  • Patients with cardiac disease, hypertension, aneurysms, thyrotoxicosis, long-standing insulin dependent diabetes mellitus and tachycardia
  • PHENYLEPHRINE 10% — children aged below 12 years: 'Phenylephrine 10% is contraindicated in children aged below 12 years.' Use in children aged 12 to 18 years is not recommended as adequate clinical experience is missing. (This restriction is stated for the 10% strength; the 2.5% strength is not covered by this source.)
  • PHENYLEPHRINE 10% — the elderly: 'The use of phenylephrine 10% solution is contraindicated in this group because of the increased risks of systemic toxicity.' (Stated for the 10% strength; the 2.5% strength is not covered by this source.)
  • Patients on monoamine oxidase inhibitors, tricyclic anti-depressants and antihypertensive agents (including beta-blockers)
  • Patients with closed angle glaucoma (unless previously treated with iridectomy) and patients with a narrow angle prone to glaucoma precipitated by mydriatics
  • Hypersensitivity to phenylephrine or to any of the excipients listed in section 6.1

Side effects

  • Frequency of all undesirable effects below is 'not known (cannot be estimated from the available data)'
  • Immune system disorders: hypersensitivity
  • Eye disorders: eye pain, eye irritation, vision blurred, photophobia, allergic conjunctivitis
  • Cardiac disorders: palpitations, tachycardia, extrasystoles, arrhythmias
  • Coronary arteriospasm, ventricular arrhythmia and myocardial infarction — 'These sometimes fatal reactions have usually occurred in patients with pre-existing cardiovascular disease'
  • Vascular disorders: hypertension
  • Paediatric population, respiratory/thoracic/mediastinal disorders: pulmonary oedema

Interactions

  • Anti-hypertensive agents — 'Topical phenylephrine should not be used as it may reverse the action of many antihypertensive agents with possibly fatal consequences'
  • Monoamine oxidase inhibitors — increased risk of adrenergic reactions when used simultaneously with, or up to three weeks after, the administration of MAOIs
  • Tricyclic anti-depressants — the pressor response to adrenergic agents and the risk of cardiac arrhythmia may be potentiated in patients receiving tricyclic anti-depressants, or within several days of their discontinuation
  • Halothane and other anaesthetic agents that sensitise the myocardium to sympathomimetics — use with caution during general anaesthesia because of the increased risk of ventricular fibrillation
  • Cardiac glycosides or quinidine — increased risk of arrhythmias

Monitoring

  • Evaluate the anterior chamber angle before use, to reduce the risk of precipitating an attack of narrow angle glaucoma (§4.4)
  • Corneal integrity — corneal clouding may occur if phenylephrine 10% is instilled when the corneal epithelium has been denuded or damaged (§4.4)
  • Compress the lacrimal sac at the medial canthus for one minute during and after instillation, to minimise systemic absorption (§4.4)
  • Watch for cardiovascular effects — palpitations, tachycardia, arrhythmias and hypertension are listed in §4.8; the SPC has no dedicated monitoring section, so these items are drawn from §4.4 and §4.8

Clinical monograph

How it works

It is a selective alpha-1 adrenoceptor agonist that stimulates contraction of the iris dilator muscle, producing mydriasis, and constricts conjunctival blood vessels.

Prescribing in practice

  • The higher-strength preparation can cause systemic cardiovascular effects, including a rise in blood pressure, so it should be used with caution in patients with cardiovascular disease, hypertension or hyperthyroidism, and avoided where high systemic absorption is a concern.
  • It may precipitate acute angle-closure glaucoma in predisposed eyes with narrow anterior chamber angles.
  • Unlike antimuscarinic mydriatics it does not cause cycloplegia, so accommodation is preserved.

Monitoring

When the higher-strength drops are used, blood pressure and cardiovascular status should be considered, and the eye observed for the intended dilation and any pressure rise.

Counselling the patient

  • Your vision may be blurred and your eyes sensitive to light for a period after dilation, so arrange not to drive until this settles.
  • Wear sunglasses to ease light sensitivity while the pupils are dilated.
  • Tell your clinician about any heart conditions or high blood pressure before the drops are used.

Evidence & guidelines

Topical phenylephrine is a long-established mydriatic for ophthalmic examination, with its effects and cardiovascular cautions described in ophthalmology references and the SPC.

Reference: RCOphth Mydriatic Guidelines; MHRA Phenylephrine 10% Safety; SPC Minims Phenylephrine; 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.

Pathways