[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Anti-herpesvirus agents](https://durgical.com/en/pharmacology/classes/anti-herpesvirus-agents/) › Trifluridine (ophthalmic)

# Trifluridine (ophthalmic)

## Anti-herpesvirus agents?

Anti-herpesvirus agents

Antiviral eye drops for herpes simplex keratitis. They are also used for eye involvement in severe mpox.

Updated Nov 1, 2026

## Quick facts

**Group**
[Anti-herpesvirus agents](https://durgical.com/en/pharmacology/classes/anti-herpesvirus-agents/)

**Target**
Viral DNA synthesis (thymidylate synthase and DNA polymerase)

**Used for**
Primary keratoconjunctivitis

**Key effects**
Burning or stinging on instillation · Eyelid swelling

**Monitor**
Corneal healing on slit-lamp examination

**ATC**
S01AD02

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

Trifluridine is a fluorinated pyrimidine nucleoside. Its monophosphate inhibits thymidylate synthase, and its triphosphate competes with thymidine triphosphate and is built into viral and cellular DNA, which stops normal DNA synthesis. It is active against herpes simplex virus types 1 and 2, including aciclovir-resistant strains, and against vaccinia. Because it also affects human cells, it is used only on the eye.

- Trifluridine is phosphorylated in the cell
- Its monophosphate inhibits thymidylate synthase
- Its triphosphate is built into viral DNA
- Viral DNA synthesis fails

## Indications

- Primary keratoconjunctivitis and recurrent epithelial keratitis due to herpes simplex virus types 1 and 2 [Keratitis and corneal ulcer →](https://durgical.com/en/conditions/keratitis-and-corneal-ulcer/)
- Eye involvement in severe mpox, together with tecovirimat [Mpox →](https://durgical.com/en/conditions/mpox/)

## Adverse effects

### Common

- Burning or stinging on instillation
- Eyelid swelling
- Punctate keratopathy and irritation

### Serious (rare, important)

- Corneal epithelial toxicity with prolonged use
- Raised intraocular pressure
- Hypersensitivity reactions

## Contraindications

- Hypersensitivity or chemical intolerance to trifluridine

## Key interactions

**Systemic medicines**
No interactions are listed; systemic absorption appears negligible

## What is monitored

- Corneal healing on slit-lamp examination
- Signs of epithelial toxicity
- Intraocular pressure

## Administration and safety

- Instilled onto the cornea of the affected eye at frequent intervals while awake, as prescribed
- Continuous use beyond the recommended period is avoided because of corneal toxicity
- The dropper tip does not touch the eye

## Pregnancy and breastfeeding

Systemic exposure is minimal and animal studies were not teratogenic; it is used in pregnancy only when needed.

## Nursing care

- Explain that brief stinging is expected
- Teach correct drop technique and hand hygiene
- Report pain, worse vision or no improvement to the ophthalmologist
- Keep track of the total days of treatment

## Pharmacokinetics

**Absorption**
Penetrates the cornea; systemic absorption after eye drops appears negligible

**Half-life**
Very short in the body, which limits exposure

## Memory aid

TRI-FLU-ridine: three fluorines for the eye's herpes; drop by drop, but never for too long.

## Test yourself

Think of the answer, then tap the question to see it.

## Why is trifluridine used only on the eye?

It also inhibits human DNA synthesis, so it is too toxic for systemic antiviral use.

## Is trifluridine active against aciclovir-resistant herpes simplex?

Yes. It inhibits herpesviruses, including aciclovir-resistant strains.

## Why is prolonged use avoided?

It can damage the corneal epithelium.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/trifluridine/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 3

- [Aciclovir](https://durgical.com/en/pharmacology/aciclovir/)
- [Ganciclovir](https://durgical.com/en/pharmacology/ganciclovir/)
- [Tecovirimat](https://durgical.com/en/pharmacology/tecovirimat/)

## Related conditions 2

- [Keratitis and corneal ulcer](https://durgical.com/en/conditions/keratitis-and-corneal-ulcer/)
- [Mpox](https://durgical.com/en/conditions/mpox/)

[← Back to the class: Anti-herpesvirus agents](https://durgical.com/en/pharmacology/classes/anti-herpesvirus-agents/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - TRIFLURIDINE solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=abc1d07f-91ee-4421-bc9b-457d0ed41f4c) (DailyMed (U.S. National Library of Medicine), 2026); [Interim Clinical Treatment Considerations for Severe Manifestations of Mpox — United States, February 2023](https://www.cdc.gov/mmwr/volumes/72/wr/mm7209a4.htm) (Centers for Disease Control and Prevention (MMWR), 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=S01AD02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/trifluridine/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/trifluridine/