[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antiglaucoma agents](https://durgical.com/en/pharmacology/classes/antiglaucoma-agents/) › Timolol

# Timolol

## Antiglaucoma agents?

Antiglaucoma agents

A non-selective beta-blocker eye drop that lowers eye pressure. Enough reaches the blood to slow the heart and narrow the airways.

Updated Nov 1, 2026

## Quick facts

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

**Target**
β1 and β2 adrenergic receptors

**Used for**
Open-angle glaucoma · Ocular hypertension

**Key effects**
Brief blurred vision after the drop · Eye pain

**Monitor**
Intraocular pressure · Pulse and blood pressure

**ATC**
S01ED01

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

◎**β1 and β2 adrenergic receptors**Timolol

ⓘ The figure shows timolol bound to the human β2 adrenergic receptor (crystal also holding cholesterol).

**Target in 3D:** β1 and β2 adrenergic receptors. PDB structure 3D4S (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/3D4S) · Drag to rotate · pinch to zoom

Timolol blocks β1 and β2 receptors without intrinsic sympathomimetic or local anaesthetic activity. In the eye its main effect is less formation of aqueous humour by the ciliary body, so intraocular pressure falls. The drug is absorbed into the bloodstream from the eye, so it can produce the same effects as an oral beta-blocker: slow heart rate, low blood pressure, heart failure and bronchospasm.

- Timolol blocks β receptors of the ciliary body
- Less aqueous humour is produced
- Intraocular pressure falls
- Drug absorbed into the blood blocks β1 (heart) and β2 (bronchi)

## Indications

- Open-angle glaucoma [Open-angle glaucoma →](https://durgical.com/en/conditions/open-angle-glaucoma/)
- Ocular hypertension
- Acute angle-closure glaucoma, only together with other treatment (never on its own) [Acute angle-closure glaucoma →](https://durgical.com/en/conditions/acute-angle-closure-glaucoma/)

## Adverse effects

### Common

- Brief blurred vision after the drop
- Burning and stinging
- Eye pain, itching, tearing or a foreign-body feeling
- Headache and dizziness

### Serious (rare, important)

- Bradycardia, hypotension, fainting
- Heart failure, or worsening of it
- Bronchospasm, severe in asthma
- Masked signs of hypoglycaemia in diabetes
- Depression, confusion, more muscle weakness in myasthenia gravis

## Contraindications

- Bronchial asthma, now or in the past
- Severe COPD
- Sinus bradycardia, second- or third-degree AV block
- Overt heart failure or cardiogenic shock
- Hypersensitivity to any component

## Key interactions

**Oral beta-blockers or a second beta-blocker eye drop**
Additive beta-blockade, on the eye and on the body; two topical beta-blockers are not combined

**Verapamil or diltiazem (oral or IV calcium antagonists), digoxin**
More slowing of AV conduction, low blood pressure or heart failure

**CYP2D6 inhibitors (quinidine, SSRIs)**
Stronger systemic beta-blockade, such as a slower pulse

**Epinephrine for anaphylaxis**
Patients may not respond to usual doses of epinephrine

## What is monitored

- Intraocular pressure
- Pulse and blood pressure
- Wheeze or shortness of breath
- Blood glucose in diabetes

## Administration and safety

- After the drop, light pressure on the inner corner of the eye (tear duct) and closed eyes for 2–3 minutes reduce the amount that reaches the blood.
- Other eye medicines are given at least 10 minutes before or after timolol.
- Soft contact lenses come out before the drop and go back in 15 minutes later.
- The surgeon and anaesthetist are told about timolol before surgery, since beta-blockade blunts heart responses.

## Pregnancy and breastfeeding

There are no adequate studies in pregnant women; it is used only if the benefit justifies the risk to the fetus.

## Nursing care

- Before the first dose, ask about asthma, COPD, slow pulse, heart block or heart failure.
- Check pulse and blood pressure at the start and at follow-up.
- In diabetes, explain that the racing heart of hypoglycaemia may not appear.
- Teach the patient to report wheeze, breathlessness, fainting, a slow pulse or swollen ankles.
- Teach the tear-duct pressure technique.

## Pharmacokinetics

**Absorption**
Absorbed into the systemic circulation after eye drops; measurable in plasma

**Onset and duration**
The pressure-lowering effect lasts about a day; in some patients the response takes a few weeks to stabilise

## Memory aid

«A drop in the eye is a pill in the blood»: timolol can slow the heart and tighten the bronchi, so ask about asthma first.

## Test yourself

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

## How does timolol lower intraocular pressure?

It reduces the production of aqueous humour by the ciliary body.

## Why is timolol eye drop contraindicated in asthma?

It is absorbed into the blood and blocks β2 receptors, which can cause severe bronchospasm.

## Which simple technique reduces systemic absorption of an eye drop?

Pressing on the tear duct (inner corner of the eye) and keeping the eyes closed for a few minutes.

## Which heart rhythm findings contraindicate timolol?

Sinus bradycardia and second- or third-degree AV block.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/timolol/)

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

## Connections

## Related drugs 4

- [Propranolol](https://durgical.com/en/pharmacology/propranolol/)
- [Latanoprost](https://durgical.com/en/pharmacology/latanoprost/)
- [Dorzolamide](https://durgical.com/en/pharmacology/dorzolamide/)
- [Brimonidine](https://durgical.com/en/pharmacology/brimonidine/)

## Related conditions 2

- [Open-angle glaucoma](https://durgical.com/en/conditions/open-angle-glaucoma/)
- [Acute angle-closure glaucoma](https://durgical.com/en/conditions/acute-angle-closure-glaucoma/)

[← Back to the class: Antiglaucoma agents](https://durgical.com/en/pharmacology/classes/antiglaucoma-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 - TIMOLOL MALEATE OPHTHALMIC GEL FORMING SOLUTION solution, gel forming / drops](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e93036c6-3120-e989-e053-2a95a90acf7f) (DailyMed (U.S. National Library of Medicine), 2026); [Timolol Ophthalmic: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682043.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=S01ED01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [RCSB PDB - 3D4S: Cholesterol bound form of human beta2 adrenergic receptor.](https://www.rcsb.org/structure/3D4S) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/timolol/
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