Skip to main content

Phenylephrine Ophthalmic

Mydfrin, Neo-Synephrine Ophthalmic

Calculate dosage
Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.

Drug Class

Ophthalmic

Routes

TOPICAL (ophthalmic)

Indications

conjunctival decongestionMydriasisMydriasis without cycloplegiaposterior synechiae prevention

Mechanism of Action

Alpha-1 adrenergic agonist causing contraction of iris dilator muscle (mydriasis) without cycloplegia. Also causes conjunctival vasoconstriction.

Side effects & warnings

10% concentration can cause systemic hypertension — use 2.5% in small animals. Mydriasis without cycloplegia (pupil still accommodates). Avoid in narrow-angle glaucoma.

Species with Phenylephrine Ophthalmic dosing data (2 dose rules)

Cat (Domestic)Dog (Domestic)

Species references:All Cat (Domestic) drugsAll Dog (Domestic) drugs

Evidence levels across 2 dose rules

Moderate×2

Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.

Backed by a published source

  • · Plumb's Veterinary Drug Handbook, 9th Ed

Sample dosing (2 of 2 cited rules)

A dog/cat sample is shown here. Cited dosing for all 2 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.

SpeciesRouteDoseFrequencyEvidenceSource
Dog (Domestic)TOPICAL (ophthalmic)0 1 drop 2.5% per eyePRN for exam or q6-8h therapeuticModeratePlumb's Veterinary Drug Handbook, 9th Ed
Cat (Domestic)TOPICAL (ophthalmic)0 1 drop 2.5% per eyePRN for exam or q6-8hModeratePlumb's Veterinary Drug Handbook, 9th Ed

Upgrade for Full Details

Upgrade to Pro or Student to unlock the full dose ranges and frequency for every species. The drug's mechanism, warnings, indications, and cited sources are free to read.

View Plans

Other formulations of Phenylephrine

More Ophthalmic drugs

Calculate Dosage for Phenylephrine Ophthalmic