Hypromellose
Hydroxypropyl methylcellulose
Also known as: Isopto Plain · Tears Naturale (combination) · Genteal · Hydroxypropyl methylcellulose · HPMC
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Keratoconjunctivitis sicca (dry eye) / Ocular lubrication | 1-2 drops per affected eye | Topical (Ophthalmic) | q4h to q12h (or as frequently as needed) | Ongoing | 🌍 EU |
- Keratoconjunctivitis sicca (dry eye) / Ocular lubrication: Frequency depends on the severity of dry eye. May be used as often as every 1-2 hours in severe cases.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Ocular lubrication | 1-2 drops per affected eye | Topical (Ophthalmic) | q4h to q12h (or as frequently as needed) | Ongoing | 🌍 EU |
- Ocular lubrication: Frequency depends on the severity of dry eye.
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Ocular lubrication (e.g., during anesthesia or for exophthalmos) | 1 drop per eye | Topical (Ophthalmic) | As needed | Ongoing | 🌍 EU |
- Ocular lubrication (e.g., during anesthesia or for exophthalmos): Useful to prevent corneal desiccation during anesthesia.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Hypromellose is a cellulose-based, aqueous tear substitute used to replace the aqueous component of the trilaminar tear film. It acts as a lacrimomimetic agent to provide lubrication and relieve dryness in the eye.
Clinical Pearl: It is frequently used in the management of keratoconjunctivitis sicca (KCS) or 'dry eye' in animals, often in conjunction with tear stimulants like topical cyclosporine or tacrolimus. Because it is an aqueous substitute, it requires frequent application compared to more viscous ointments or gels.
Mechanism of action
Hypromellose is a hydrophilic polymer that acts as a lacrimomimetic. It increases the viscosity of tears and prolongs corneal contact time.
Cellulose-based polymer → binds to existing tears → stabilizes the aqueous layer of the trilaminar tear film → prevents rapid tear evaporation and provides mechanical lubrication to the cornea and conjunctiva.
Safety & warnings
Contraindications
- Hypersensitivity to hypromellose or any component of the formulation (such as preservatives like benzalkonium chloride in multi-dose bottles)
Adverse effects
- Transient blurred vision immediately after application
- Mild ocular irritation or stinging (rare)
- Crusting on the eyelids from dried polymer
Precautions
Contamination Risk: Do not touch the dropper tip to any surface, including the eye or eyelid, to avoid bacterial contamination of the bottle. Timing: If using multiple topical ophthalmic medications, administer hypromellose last, or wait at least 5-10 minutes between applications to prevent washout of the preceding drug. Preservatives: Multi-dose bottles often contain preservatives (e.g., benzalkonium chloride) which can be epitheliotoxic with very frequent use (e.g., >4-6 times daily). Consider preservative-free single-use vials for severe dry eye requiring highly frequent application.
Drug interactions
May wash out other eye drops if administered simultaneously. Hypromellose can also act as a barrier if applied before other drugs.
Monitoring
- Resolution of clinical signs of dry eye (e.g., redness, mucoid discharge, blepharospasm)
- Schirmer Tear Test (STT) if managing KCS
- Corneal staining (fluorescein) to monitor for corneal ulceration secondary to dry eye
Pharmacokinetics
Half-life
Absorption
Not systemically absorbed. Acts locally on the ocular surface.
Distribution
Remains on the corneal and conjunctival surfaces.
Metabolism
Not metabolized systemically.
Elimination
Cleared from the eye via the nasolacrimal duct and normal tear turnover.
Overdose
Overdosage is highly unlikely due to the topical route of administration and lack of systemic absorption. Excess drops will simply overflow from the eye.
Available products
Formulations
- Ophthalmic solution: 0.3% (10 ml dropper bottle)
- Ophthalmic solution: 0.5% (10 ml dropper bottle)
- Ophthalmic solution: 0.32% (single-use vial)
Human-labeled
- Isopto Plain (0.5% solution)
- Various generic hypromellose 0.3% eye drops
Regulatory status
Available Over-The-Counter (OTC)
Available as Pharmacy (P) or OTC medicine depending on the specific formulation.
Classified as a Pharmacy (P) medicine in the UK.
No regulatory data for: 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature (below 25°C). Do not freeze. Discard 28 days after opening (for multi-dose bottles) to prevent bacterial contamination. Single-use vials should be discarded immediately after use.
Client information
Hypromellose is an artificial tear drop used to keep your pet's eyes moist and comfortable.
- Wash your hands before applying the drops.
- Do not let the tip of the bottle touch your pet's eye, eyelids, or your fingers to prevent contamination.
- If your pet is receiving other eye medications, wait at least 5 to 10 minutes between applying different drops. Usually, artificial tears should be applied last.
- Store the bottle as directed and discard it if the liquid becomes cloudy or changes color.
- Multi-dose bottles should typically be discarded 28 days after opening.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.