Optrex Allergy 2% w/v Eye Drops 10ml

Optrex Allergy Eye Drops 10ml – sodium cromoglicate 2% w/v for the relief and treatment of seasonal and perennial allergic conjunctivitis.

  • Mast cell stabiliser – acts on the allergic reaction itself
  • For itchy, red, watering hay fever and allergy eyes
  • Works best used regularly, four times a day, through the season
  • Same active ingredient as Opticrom Allergy eye drops
  • Dispatched by a GPhC-registered UK pharmacy

£7.99

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Optrex Allergy Eye Drops contain sodium cromoglicate 2% w/v and are used to relieve and treat allergic conjunctivitis — the itchy, red, watering eyes caused by pollen, dust mite, pet dander and mould. Unlike a redness drop, sodium cromoglicate acts on the allergic reaction itself.

What are Optrex Allergy Eye Drops?

They are a 10ml bottle of sodium cromoglicate 2% w/v eye drops, licensed for seasonal and perennial allergic conjunctivitis — that is, both hay fever eyes and year-round allergy eyes. Sodium cromoglicate is a mast cell stabiliser. Mast cells in the lining of the eye are what release histamine when an allergen lands on them; cromoglicate makes those cells less likely to degranulate, so less histamine is released in the first place.

The consequence of how it works: use it as a preventer

This is the single most useful thing to understand about these drops, and the reason people conclude they “don’t work”. Because cromoglicate stops histamine being released rather than blocking histamine already released, its effect builds up over several days of regular use. Used four times a day, every day, through the season, it works well. Used once, on the worst day, when the eyes are already streaming, it does very little.

So start it a week or two before your usual hay fever season if you can, and keep using it consistently rather than only on bad days.

What are they used for?

  • Hay fever eyes — itching, redness, watering and swollen lids during pollen season
  • Perennial allergic conjunctivitis — the same symptoms year-round from dust mite, pets or mould
  • Eyes that itch and water alongside sneezing and a runny nose, where an antihistamine tablet has helped the nose but not the eyes

They are not for eye infections, and not for dry eye or plain redness. If your eyes are simply bloodshot from irritation, see Optrex Bloodshot Eye Drops; if they are dry and gritty, Optrex ActiMist targets the tear film.

How to use them

  • One or two drops into each eye, four times a day, or as directed.
  • Use them in both eyes even if only one feels bad — allergic conjunctivitis is almost always bilateral.
  • Wash your hands first and do not let the dropper tip touch the eye or any surface.
  • Discard four weeks after opening the bottle.

Contact lenses — read this before you buy

The drops contain benzalkonium chloride as a preservative, which is absorbed by soft contact lenses and can irritate the eye. Soft lenses should not be worn during the treatment period. If you wear soft lenses daily through hay fever season, discuss the options with your optometrist or our pharmacist — switching to glasses during the worst weeks, or to a preservative-free alternative, is usually the answer.

Side effects and cautions

The drops may sting briefly on instillation and can cause transient blurring of vision — do not drive or operate machinery until your vision has cleared. If you are in the first trimester of pregnancy, check with your pharmacist or doctor before using them. Stop and seek advice if your eyes become more irritated rather than less.

Optrex Allergy or Opticrom — is there a difference?

Both contain the same active ingredient at the same strength: sodium cromoglicate 2% w/v. Opticrom Allergy Eye Drops are the alternative brand and are usually the cheaper of the two on a like-for-like basis. Clinically there is little to choose between them — pick on price and on which bottle you find easier to use. We are happy to say that plainly rather than sell you the dearer one.

An antihistamine eye drop works differently again: it blocks histamine that has already been released, so it acts faster but does not build the same background protection. For heavy hay fever, many people take an oral antihistamine such as fexofenadine 120mg and add an eye drop for the eyes specifically. Browse the full eye care and allergy relief ranges.

When to get your eyes checked

Allergic conjunctivitis itches. If instead you have pain, reduced vision, marked light sensitivity, a sticky yellow-green discharge or one eye much worse than the other, that is not allergy — see an optometrist, GP or 111.

Buy Optrex Allergy Eye Drops online

Bury Healthcare Online is a GPhC-registered UK pharmacy (registration 1126145). Your order is checked and dispatched by our pharmacy team, and our pharmacist can advise on combining eye drops with an oral antihistamine.

Always read the label and the patient information leaflet before use. If symptoms do not improve, speak to your pharmacist or doctor.

Medically reviewed by Hassan Khan, MPharm, Independent Prescriber — Superintendent Pharmacist, Bury Healthcare Online (GPhC-registered pharmacy 1126145). Last reviewed: July 2026.

Optrex Allergy Eye Drops FAQs

What are Optrex Allergy Eye Drops used for?
They contain sodium cromoglicate 2% and are used to relieve and treat seasonal and perennial allergic conjunctivitis – the itchy, red, watering eyes caused by pollen, dust mite, pet dander or mould.
How long do Optrex Allergy Eye Drops take to work?
Sodium cromoglicate is a mast cell stabiliser, so its effect builds over several days of regular use rather than working instantly. Use it four times a day, every day, and judge it after about a week. Used only on bad days it will seem ineffective – that is a dosing problem, not a product problem.
Should I start using them before hay fever season?
Ideally yes. Because it prevents histamine being released rather than blocking histamine already released, starting a week or two before your usual season and continuing through it works much better than starting once symptoms are severe.
Can I wear contact lenses while using them?
No – soft contact lenses should not be worn during the treatment period. The drops contain benzalkonium chloride, which is absorbed by soft lenses and can irritate the eye. If you wear lenses daily through pollen season, speak to your optometrist or our pharmacist about the alternatives.
How often should I use them?
One or two drops into each eye, four times a day. Use both eyes even if only one is troubling you, as allergic conjunctivitis is nearly always bilateral.
What is the difference between Optrex Allergy and Opticrom?
They contain the same active ingredient at the same strength – sodium cromoglicate 2% w/v. Clinically there is little to choose between them, and Opticrom is usually the cheaper of the two. Choose on price and on which bottle you prefer to use.
Can I use them with antihistamine tablets?
Yes, and many people do. An oral antihistamine treats the nose, throat and general symptoms; the eye drops act directly on the eye surface, which oral antihistamines often do not fully control. Ask your pharmacist if you are taking other medicines.
Will they blur my vision?
They can cause brief blurring just after you put them in. Do not drive or operate machinery until your vision has returned to normal – usually a minute or two.
How long do the drops last once opened?
Discard the bottle four weeks after opening it, even if drops remain.
Are they safe in pregnancy?
Check with your pharmacist or doctor before using them in the first trimester of pregnancy. As with any medicine in pregnancy, it is worth a quick conversation rather than an assumption.

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