Combigan Eye Drops (Brimonidine/Timolol): Uses, Dosage & Side Effects

✓ Medically reviewed by  ·  Last reviewed: May 2026

Morgan Ellis

Pharmacy Researcher · 8 years experience

Pharmacy researcher with 8 years reviewing clinical drug information, generic formulation equivalence, and international pharmaceutical standards. Focuses on patient-facing accuracy in medication education.

Combigan eye drops are a fixed-combination glaucoma treatment that packs two different pressure-lowering medicines — brimonidine and timolol — into a single bottle. It is used when one eye drop is no longer enough to control the pressure inside the eye, and it is popular precisely because it replaces two separate bottles with one twice-daily drop. This guide explains, in plain English, what is inside Combigan, how the two drugs lower eye pressure in completely different ways, how to use it correctly, the side effects, and — importantly — the asthma and heart conditions that make it unsafe for some people, plus how it compares with the other glaucoma drops available.

What Are Combigan Eye Drops?

Combigan is a fixed-dose combination eye drop for glaucoma and ocular hypertension. Each drop delivers two established pressure-lowering medicines at once:

• Brimonidine tartrate 0.2% — a selective alpha-2 adrenergic agonist. It is the same molecule found in stand-alone brimonidine drops.
• Timolol maleate 0.5% — a non-selective beta-blocker, and the single most widely used pressure-lowering eye drop in the world. On its own it is sold as Iotim (timolol).

The point of combining them is simple: raised pressure inside the eye is the one risk factor for glaucoma that treatment can change, and many people need more than one drug to bring it down far enough. Rather than instil two separate bottles, Combigan puts both actives in one, dosed twice daily. It sits alongside the prostaglandins, beta-blockers and carbonic anhydrase inhibitors covered in our guide to the best glaucoma eye drops, and within the wider eye care range.

How Combigan Eye Drops Work

The pressure inside your eye depends on a balance between the fluid (aqueous humour) your eye makes and the fluid it drains away. If production outpaces drainage, pressure rises and, over years, can quietly damage the optic nerve — that is glaucoma. Combigan lowers pressure by acting on both sides of that balance:

• Timolol switches down the “tap.” By blocking beta-receptors on the ciliary body, it reduces how much aqueous fluid the eye produces.
• Brimonidine works on both the tap and the drain. It also reduces fluid production, and — unusually — it increases uveoscleral outflow, an alternative drainage route out of the eye.

Because the two drugs overlap on production but brimonidine adds a drainage effect the beta-blocker does not have, the combination lowers intraocular pressure more than either component alone — typically by roughly a quarter to a third from the starting pressure. That “attack both mechanisms” logic is the whole reason fixed-combination drops exist.

Combigan Eye Drops Dosage and How to Use Them

The standard dose is one drop in the affected eye (or eyes) twice a day, spaced about 12 hours apart — for example morning and evening. Do not exceed twice daily; more frequent dosing does not lower pressure further and increases side effects. Technique matters far more than people expect, because good technique both improves absorption into the eye and reduces absorption into the body:

1. Wash your hands and, if you wear soft contact lenses, take them out first (see below).
2. Tilt your head back, pull the lower eyelid down to make a small pocket, and hold the bottle above the eye without touching the tip to your eye, lashes or fingers.
3. Squeeze one drop into the pocket. A single drop is all the eye can hold — a second just overflows and is wasted.
4. Close the eye gently (do not squeeze or blink hard) and press on the inner corner, next to the nose, for about one minute. This punctal occlusion stops the drop draining into your tear duct and being absorbed into your bloodstream — the key trick for reducing the beta-blocker’s body-wide effects.
5. Wait at least 5 minutes before instilling any other eye drop, so the first is not washed straight out by the second.
6. Wait about 15 minutes before putting soft contact lenses back in — the preservative in the drop can be absorbed by the lens.

If you miss a dose, take it when you remember unless it is nearly time for the next one; never double up. And never share a glaucoma drop or stop it suddenly without advice — pressure rebounds quickly.

Why a Fixed Combination Instead of Two Bottles?

This is the feature that makes Combigan genuinely useful, and it is the part most short product descriptions skip. Glaucoma is almost entirely symptomless until late, so the biggest real-world problem is not which drug you use — it is remembering to use it every single day, for years. A fixed combination helps in several concrete ways:

• Fewer drops and fewer bottles. One twice-daily bottle instead of two separate regimens means far better adherence — the single strongest predictor of whether glaucoma is actually controlled.
• Less preservative exposure. Using one combination bottle exposes the eye surface to less benzalkonium chloride than two separate preserved bottles, which matters for the dry, irritated eyes many long-term glaucoma patients develop.
• No wash-out. Two separate drops taken too close together can rinse each other out; one combined drop removes that problem entirely.

Combigan is generally introduced as a step up — when a single drop is no longer holding the pressure down — or to consolidate a patient already taking separate brimonidine and timolol into one simpler bottle. You can see current packs on the Combigan eye drop product page.

Side Effects of Combigan

Most side effects are mild and local, but because Combigan contains a beta-blocker, some are body-wide and clinically important. They fall into two groups, reflecting the two drugs:

From the brimonidine — ocular and mild systemic:

• Allergic conjunctivitis — red, itchy, watery eyes. This is the classic brimonidine reaction and can appear months after starting, not just at the beginning.
• Burning or stinging on instillation, a gritty foreign-body feeling, and briefly blurred vision.
• Dry mouth, drowsiness or fatigue, dizziness and occasionally a drop in blood pressure.

From the timolol (beta-blocker) — systemic and worth taking seriously:

• A slower heart rate and lower blood pressure.
• Breathing problems — a beta-blocker can trigger wheeze or bronchospasm in anyone with reactive airways, which is why the airway cautions below matter.
• Tiredness, low mood, and — importantly for people with diabetes — it can mask the warning signs of low blood sugar such as a racing heart.

The guiding principle is to use the drops exactly as directed, use punctal occlusion every time to keep the beta-blocker out of your system, and report any breathlessness, slow pulse, fainting or a persistently red, itchy eye to your prescriber.

Who Should Not Use Combigan

This is the most important section, because the timolol in Combigan is a genuine beta-blocker and the brimonidine has its own hard limits. Combigan should not be used if you have:

• Asthma, or a history of it, or severe COPD — the beta-blocker can cause a dangerous narrowing of the airways. A beta-blocker-free drop such as Azopt (brinzolamide) is the safer route here.
• A slow heart rate (sinus bradycardia), second- or third-degree heart block, overt heart failure or cardiogenic shock.
• Babies and children under 2 years — brimonidine can cross into the brain and cause dangerous drowsiness and slowed breathing in the very young.
• Treatment with an MAOI antidepressant.

Use it only with medical supervision if you take an oral beta-blocker or a calcium-channel blocker (the heart effects add up), if you have diabetes, depression, reduced kidney or liver function, or circulation problems such as Raynaud’s. Always tell your prescriber every medicine you take — including drops for the other eye.

Combigan vs the Other Glaucoma Eye Drops

Combigan is one of several ways to lower eye pressure, and the right choice depends on the molecules, how many times a day you can realistically use drops, and — critically — whether you can safely take a beta-blocker. Here is how the main options compare:

The practical read: if you tolerate a beta-blocker and need two drugs, Combigan is a solid, well-established choice. If you cannot take a beta-blocker (asthma, slow heart), a beta-blocker-free combination — brinzolamide plus brimonidine (Simbrinza) — or a single beta-blocker-free drop such as Azopt is safer. And if a strict once-daily routine matters most, a prostaglandin such as Xalatan or the once-daily latanoprost-timolol combination Lacoma-T may fit your life better. Our glaucoma eye drops guide walks through all of them side by side.

Is There a Generic Version of Combigan?

Yes. Both brimonidine and timolol are long-established, off-patent molecules, so the exact same 0.2%/0.5% combination is manufactured generically as brimonidine/timolol. A generic is not a weaker or different medicine — it is the same two actives at the same concentrations, produced to WHO-GMP-certified manufacturing standards. The only meaningful difference is price: the generic combination typically costs a fraction of the originator brand for an identical effect on eye pressure.

Ordering Combigan and Generic Brimonidine/Timolol

At MedsBase you can order Combigan eye drops — no prescription needed, with the medicine sourced from WHO-GMP-certified manufacturers. You can browse the full range of pressure-lowering drops in the eye care category.

That said, glaucoma is a serious, largely symptomless condition: it damages the optic nerve silently, and lowering pressure slows that damage but does not cure it. Combigan controls pressure — it does not replace the eye examinations that tell you whether that pressure is low enough. If you have not been formally diagnosed, or your vision is changing, get assessed by an eye specialist, and have your eye pressure and optic nerve checked regularly. Use this guide to understand your treatment, not to replace an eye exam.

📦 Every MedsBase order is covered by our Reshipment Assurance Policy — if your parcel does not arrive within 20 business days, we reship it.

Frequently Asked Questions

What is Combigan used for?

Combigan is used to lower raised pressure inside the eye in people with open-angle glaucoma or ocular hypertension. It is generally used when a single eye drop is not enough on its own, combining two pressure-lowering medicines — brimonidine and timolol — in one bottle.

How does Combigan lower eye pressure?

It works on both sides of the eye’s fluid balance. The timolol reduces how much fluid the eye produces, while the brimonidine both reduces production and improves drainage out of the eye. Because they act by different mechanisms, together they lower pressure more than either one alone.

How often do you use Combigan eye drops?

The usual dose is one drop in the affected eye or eyes twice a day, about 12 hours apart. Using it more often does not lower pressure further and increases the risk of side effects.

What are the most common side effects of Combigan?

The most common are eye redness, itching and a burning or stinging feeling, along with dry mouth and drowsiness from the brimonidine. Brimonidine can also cause an allergic eye reaction that sometimes appears months after starting. The timolol component can slow the heart rate and, in susceptible people, affect breathing.

Who should not use Combigan?

Combigan should be avoided by anyone with asthma or severe COPD, a slow heart rate, certain heart-rhythm or heart-failure problems, babies and children under two years, and people taking an MAOI antidepressant. It should be used with medical supervision by anyone on an oral beta-blocker or with diabetes, depression or reduced kidney or liver function.

Can I use Combigan if I have asthma?

No. The timolol in Combigan is a beta-blocker, and beta-blockers — even as eye drops — can trigger a dangerous narrowing of the airways in people with asthma or significant airway disease. A beta-blocker-free drop, such as brinzolamide (Azopt) or a brinzolamide-brimonidine combination, is the safer option in that situation.

Is there a generic version of Combigan?

Yes. Brimonidine and timolol are both off-patent, so the identical 0.2%/0.5% combination is sold generically as brimonidine/timolol, made to WHO-GMP-certified standards. It contains the same actives at the same strengths as the brand, usually at a much lower price.

Can Combigan be used with other glaucoma drops?

Often, yes — glaucoma is frequently treated with more than one type of drop, for example adding a prostaglandin. If you use more than one eye drop, leave at least five minutes between them so the first is not washed out, and always have your full list of drops confirmed by an eye specialist.

Why should I press on the corner of my eye after using Combigan?

Pressing gently on the inner corner of the eye next to the nose for about a minute — called punctal occlusion — stops the drop draining into the tear duct and being absorbed into your bloodstream. This keeps more of the medicine in the eye and reduces the beta-blocker’s body-wide side effects.

Written by

Sophie Chen

Pharmaceutical Content Researcher · 8 years experience

Sophie Chen is a pharmaceutical content researcher with 8 years covering generic medication access and clinical pharmacology. She specialises in international regulatory frameworks, bioequivalence standards, and patient-facing education on therapeutic drug classes. She is not a clinician.