[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Diagnostic agents](https://durgical.com/en/pharmacology/classes/diagnostic-agents/) › Fluorescein

# Fluorescein

## Diagnostic agents?

Diagnostic agents

An orange dye that glows green under blue light. On the eye it shows corneal scratches; injected, it outlines the retinal vessels.

Updated Nov 1, 2026

## Quick facts

**Group**
[Diagnostic agents](https://durgical.com/en/pharmacology/classes/diagnostic-agents/)

**Target**
No receptor: a fluorescent dye (absorbs blue light, emits yellow-green light)

**Used for**
Corneal staining to find abrasions

**Key effects**
Nausea · Mild · Headache

**Monitor**
Hives · The injection site

**ATC**
S01JA01

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

Fluorescein absorbs blue light and gives off yellow-green light. As an eye drop or paper strip it spreads over the tear film; areas where the corneal epithelium is damaged take up the dye and glow green under a blue light. Injected into a vein, it travels to the retina within seconds, and a fundus camera with a blue flash records the retinal and choroidal vessels (fluorescein angiography), showing leaks and closed vessels.

- Fluorescein absorbs blue light and emits green light
- On the eye: damaged cornea takes up the dye and glows
- In a vein: the dye fills retinal vessels and is photographed

## Indications

- Corneal staining to find abrasions and foreign bodies [Corneal abrasion and ocular foreign body →](https://durgical.com/en/conditions/corneal-abrasion-and-ocular-foreign-body/)
- Corneal surface damage in dry eye [Dry eye disease →](https://durgical.com/en/conditions/dry-eye-disease/)
- Fluorescein angiography of the retina and iris, for example in diabetic retinopathy [Diabetic retinopathy →](https://durgical.com/en/conditions/diabetic-retinopathy/)

## Adverse effects

### Common

- Yellow skin and bright yellow urine after injection (harmless, temporary)
- Nausea, vomiting and a strong taste after injection
- Mild, brief sting from eye drops; dye can stain skin and clothes
- Headache; pain or phlebitis at the injection site

### Serious (rare, important)

- Anaphylaxis, rarely fatal; hives, bronchospasm
- Fainting, hypotension, and rarely cardiac arrest or shock
- Extravasation: skin sloughing, phlebitis, nerve inflammation
- Seizures (rare)

## Contraindications

- Hypersensitivity to fluorescein or another ingredient
- Caution with allergies or asthma (emergency equipment ready)

## Key interactions

**Topical anaesthetic drops**
Often combined with fluorescein in the same drop; without an anaesthetic the dye may sting briefly

## What is monitored

- Hives, breathing and blood pressure during and after injection
- The injection site, for extravasation

## Administration and safety

- Glasses and contact lenses come off before an eye stain test.
- For angiography, a well-placed vein is used; if the dye leaks, the injection is stopped and the area treated conservatively.
- An emergency tray is kept at hand; a negative skin test does not rule out allergy.

## Pregnancy and breastfeeding

Animal data are insufficient, so injected fluorescein is used in pregnancy only if clearly needed; it passes into breast milk.

## Nursing care

- Ask about earlier reactions to fluorescein, allergies and asthma.
- Explain that skin and urine will look yellow for a while and that this is expected.
- Keep a basin ready for nausea and watch for hives or breathlessness.
- Check the IV site for pain or swelling during the injection.

## Pharmacokinetics

**Distribution**
After injection in the arm it reaches the central retinal artery within seconds and spreads into the tissues

**Metabolism**
Converted to fluorescein monoglucuronide

**Elimination**
Mainly by the kidney, essentially gone within 48–72 hours; yellow skin fades in 6–12 hours and yellow urine in 24–36 hours

## Memory aid

«Orange in, green out»: under blue light, a scratch on the cornea lights up green.

## Test yourself

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

## What does a corneal abrasion look like after fluorescein under blue light?

A bright green-stained area where the epithelium is missing.

## Which harmless effect should every patient know about after fluorescein angiography?

Yellow skin and bright yellow urine for some hours.

## What is the most feared reaction to injected fluorescein?

Anaphylaxis, which is rare but can be fatal.

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

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

## Connections

## Related drugs 1

- [Tropicamide](https://durgical.com/en/pharmacology/tropicamide/)

## Related conditions 3

- [Corneal abrasion and ocular foreign body](https://durgical.com/en/conditions/corneal-abrasion-and-ocular-foreign-body/)
- [Dry eye disease](https://durgical.com/en/conditions/dry-eye-disease/)
- [Diabetic retinopathy](https://durgical.com/en/conditions/diabetic-retinopathy/)

[← Back to the class: Diagnostic agents](https://durgical.com/en/pharmacology/classes/diagnostic-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 - FLUORESCEIN injection](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0a2a65b1-dc88-445b-bfb7-53b2fd7bea2c) (DailyMed (U.S. National Library of Medicine), 2026); [Fluorescein eye stain: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003845.htm) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=S01JA01) (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/fluorescein/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/fluorescein/