Allergic conjunctivitis — the itchy-eye side of allergy

About this guide

Allergic conjunctivitis is the “eye version” of the same allergic process that causes runny nose, itchy nose, and sneezing. If you’ve been diagnosed with allergic rhinitis, there’s a very high chance your eye symptoms are the same story in a different place — the two conditions coexist in roughly 60–75% of atopic patients and are often grouped together as “allergic rhinoconjunctivitis.”

This guide is a companion to our allergic rhinitis guide, focused specifically on the eye symptoms. It applies to adults and children, with paediatric-specific notes flagged where they matter.

If you’re here because of eye symptoms that keep coming back — itchy, watery, sometimes crusty in the morning — this guide is for you.

Does this sound familiar?

A story we hear often, especially from parents of young children:

“By about 10 in the evening, she starts rubbing her eyes — pressing them with her knuckles, then the backs of her hands, then her forearms. She’ll rub them red. Sometimes she wakes the next morning with her lashes stuck together and a bit of crust on the corners. She says it’s not painful — just ‘my eyes feel funny.’ She rubs them again on the way to school and after coming home. This has been going on for months. The kindergarten teacher keeps asking if she has eye infection.”

Or, from an adult:

“My eyes itch all the time. They water when I wake up, and I have to rub them before I can really open them. If I touch my eye, it flares up worse for half an hour. I’ve bought every eye drop at the pharmacy. Some help a bit for an hour or two, then it’s back.”

These are both classic allergic conjunctivitis. A few features tend to stand out:

• Itch is the dominant symptom — not pain
• Symptoms peak in the evening and early morning — after a full day of exposure and after a night on the pillow (where dust-mite allergen concentrates)
• Rubbing gives a moment of relief but makes things meaningfully worse for the next hour or two
• Morning crusting — collected discharge overnight; usually clear or whitish (not the thick yellow-green of a bacterial infection)
• Symptoms wax and wane over weeks or months, rather than running a clean 7–10 day course like a viral infection
• Often travels with nasal symptoms — even mild ones like a bit of morning sneezing or a stuffy nose in bed

The eye-rubbing is often the first thing a parent notices. It’s worth taking seriously — children can rub hard enough to cause corneal abrasions and, in the more severe forms of allergic eye disease, actual structural damage.

What is allergic conjunctivitis?

The conjunctiva is the thin, transparent lining that covers the white of the eye and the inside of the eyelids. Like the lining of the nose, it’s richly supplied with mast cells — immune cells that release histamine when they recognise an allergen. In an allergic person, exposure to the allergen (most commonly house dust mite here in Singapore) triggers these cells to release histamine and other mediators, producing:

• Itching — the cardinal symptom; absence of itch makes allergic conjunctivitis unlikely
• Redness (conjunctival injection — visible dilated blood vessels)
• Tearing and watering
• Mild swelling of the conjunctiva (chemosis) or eyelids
• A gritty, foreign-body sensation — not true pain
• Clear or whitish discharge, usually worst on waking

It is not an infection. You cannot catch it from someone; your child cannot give it to their classmates. This is one of the most common misunderstandings — and leads to unnecessary time off school, unnecessary antibiotic eye drops, and unnecessary worry.

How we recognise it on examination

When we examine the eye of a patient with allergic conjunctivitis, we typically see:

• Conjunctival injection — redness, usually diffuse rather than focal, often more marked in the lower and inner parts of the eye
• Papillary or follicular pattern on the inner (tarsal) surface of the eyelids — tiny raised bumps from the inflamed lymphoid tissue beneath
• Allergic shiners — darker discolouration of the skin under the eyes, from slowed venous drainage around the inflamed area
• Dennie–Morgan lines — sometimes — extra horizontal creases below the lower eyelids, a classic atopic sign
• Periorbital puffiness — mild swelling of the soft tissues around the eye
• Clear, watery discharge, sometimes with a few whitish strands — very different from the thick yellow-green of bacterial conjunctivitis

We typically do not need special tests. The diagnosis is clinical — the story and the examination usually make it clear.

Types of allergic conjunctivitis

The common patterns we see:

• Perennial allergic conjunctivitis (PAC) — year-round symptoms, driven by indoor allergens (house dust mite, moulds, pet dander). This is by far the commonest form in Singapore, and usually pairs with perennial allergic rhinitis.
• Seasonal allergic conjunctivitis (SAC) — symptoms follow a seasonal pattern, usually driven by pollen. Uncommon in Singapore but seen in patients who spent years in temperate countries.
• Contact allergic conjunctivitis — caused by something touching the eye: cosmetics, eye makeup, contact lens solution, or the preservatives in eye drops themselves (benzalkonium chloride is a common culprit). Symptoms usually settle within a week or two once the trigger is removed.

Most of what we see in primary care is perennial, dust-mite-driven, and responds well to the treatment outlined below.

What’s triggering it in Singapore

The triggers are essentially the same as for allergic rhinitis — see the allergic rhinitis guide for detail. Briefly:

• House dust mite dominates, as it does for AR. Over 80% of atopic people in Singapore are sensitised.
• Pet dander is a common additional trigger in pet-owning households.
• Moulds in damp, poorly-ventilated areas.
• Non-allergenic irritants that amplify symptoms without being true allergens — cigarette smoke, strong perfumes, incense, chlorinated swimming pools, air-conditioning blown directly at the eyes.
• Contact triggers — eye makeup, eye-drop preservatives, contact lens solutions, skincare that migrates into the eye during sleep.

If you’ve already identified house dust mite as the driver of your nose symptoms, the same measures (dust-mite-proof bed covers, hot-wash bedding, bedroom decluttering) benefit your eyes too, since most overnight exposure happens with your face on the pillow.

Why treat it — what you get back

People often put up with chronic eye itch for years, treating it occasionally with whatever “red eye” drop is nearest. Properly treated, here’s what usually comes back:

• Mornings without stuck-together lashes and a gritty start to the day
• Fewer headaches — chronic squinting and low-grade eye irritation quietly drive tension-type headaches
• Better concentration and screen tolerance — especially at work and in children doing schoolwork
• Fewer episodes of superimposed bacterial infection — chronic rubbing breaks the eye’s natural defences and occasionally introduces bacteria
• Less risk of corneal damage from rubbing — particularly important in children who rub very hard
• Preservation of contact lens wear — for patients who’ve given up lenses because of irritation
• Better overall allergy control — the eye and nose share the same allergic drive, and addressing both usually helps both

Treatment — practical options

Non-pharmacological measures (do these regardless of medication)

• Cold compresses are genuinely effective. A clean, cool, damp cloth laid over closed eyes for 5–10 minutes reduces itch and swelling surprisingly well. Kept in the fridge, they’re even better. In children, a cool gel eye-mask made for this purpose (available at most pharmacies) is an easy household tool.
• Preservative-free artificial tears — single-dose unit vials, used through the day — physically wash allergen away from the ocular surface, dilute inflammatory mediators, and ease the gritty sensation. Brands commonly available locally include Systane UD, Refresh Plus, Tears Naturale Free, and Hyabak.
• Avoid rubbing — easier said than done, especially for children. Rubbing feels like it helps for a moment because mechanical pressure briefly reduces itch — but it triggers mast cells to release more histamine within minutes, and the itch comes back worse. Replacing the rub with a cold compress, a splash of cool water, or a single drop of artificial tears breaks the cycle.
• Wash the face before sleep to remove pollen, dust, and skincare/makeup residue from around the eyes.
• Trigger reduction — bedroom dust-mite measures (see the AR guide) help eye symptoms, since dust-mite concentration in bedding is the overnight exposure.
• Consider the eye makeup — mascara, eyeliner, and false-lash adhesive are common hidden contributors in adult women. A two-week break often settles things.

First-line: dual-action eye drops

Modern eye-allergy drops combine two actions in one drop — they block histamine (antihistamine) and stabilise mast cells so they release less histamine in the first place. The combination is faster than pure mast cell stabilisers and longer-lasting than pure antihistamine drops. This is now the standard first-line treatment.

Commonly used in Singapore:

• Olopatadine 0.1% — Patanol. Twice-daily drop, registered for children from 3 years of age.
• Olopatadine 0.2% — Pataday. Once-daily drop (the higher concentration allows longer dosing intervals), also registered from 3 years.
• Ketotifen 0.025% — Zaditen. Twice- to three-times daily drop, registered from 3 years.

Other dual-action drops (epinastine, bepotastine, alcaftadine) are used internationally but availability in Singapore varies — we’d discuss at the visit if we’re considering something other than the standard options.

Points worth knowing:

• These drops take a few days to a week of consistent use to reach full effect — give them time before concluding they aren’t working
• Used twice daily (or once for Pataday), ideally morning and evening
• Safe for long-term daily use — we routinely prescribe them for months at a time during high-symptom seasons
• The bottle typically has a preservative (benzalkonium chloride), which is generally fine but can occasionally irritate very sensitive eyes or dry-eye sufferers. Preservative-free unit-dose formulations exist in some regions; ask at your visit.
• Keep the bottle tip from touching the eye or lashes (to avoid contamination)

Oral antihistamines — a supporting role

Oral second-generation antihistamines (loratadine — Clarityn; cetirizine — Zyrtec; fexofenadine — Telfast; bilastine — Bilaxten) are very useful when nose and eye symptoms coexist, which is most of the time. For eye symptoms alone, however, they are less effective than a topical eye drop — the drug has to reach the eye via the bloodstream, which is slower and less concentrated than instilling it directly.

A common pattern we use:

• If only eye symptoms → dual-action eye drops
• If both eye and nose symptoms → nasal corticosteroid spray + dual-action eye drops, with or without an oral antihistamine
• If only nose symptoms → nasal corticosteroid spray ± oral antihistamine (see the AR guide)

Oral antihistamines can occasionally dry the eyes, especially cetirizine and levocetirizine, which is worth knowing if your eyes feel gritty rather than itchy — sometimes a switch of antihistamine helps.

A note on sodium cromoglycate

For many years, sodium cromoglycate eye drops (Allergocrom, Opticrom) were the standard children’s option — a pure mast cell stabiliser with an excellent safety record. In current practice, Allergocrom is no longer widely available in Singapore, and the dual-action drops above have largely taken over the same role. If you’ve used cromoglycate-based drops in the past and are looking for a replacement, the dual-action drops cover the same need with better effect — olopatadine (Patanol/Pataday) and ketotifen (Zaditen) are the usual substitutes, both registered for children from 3 years.

What we generally don’t recommend

• “Red eye relief” decongestant drops — tetrahydrozoline (Eye-Mo, Visine), naphazoline (Naphcon). These shrink blood vessels quickly and make the eye whiter, but they don’t address the underlying allergy. Used beyond a few days, they cause rebound redness when the effect wears off (a “conjunctival medicamentosa” similar to rhinitis medicamentosa with nasal decongestants) and set up a cycle of dependence. For a wedding or a meeting, occasional use is fine; regular use isn’t.
• Antibiotic eye drops (chloramphenicol, tobramycin, gentamicin, fusidic acid) — prescribed very commonly for “pink eye,” but unnecessary for allergic conjunctivitis (which is not an infection), and excessive use both promotes resistance and can cause contact allergy to the drops themselves. We use these only for genuine bacterial conjunctivitis.
• Long-term use of any eye drop without review — even safe drops should be reviewed periodically. The eye is a delicate organ and long-term medication deserves attention.
• Rubbing to “clear” the eye — see above. The rub feels helpful for seconds and worsens things for hours.

Children — age-specific notes

Instilling eye drops in a resistant child

Eye drops are one of the harder medications to give a young child. A few techniques that work:

• Have the child lie flat on their back, eyes gently closed. Place a drop in the inner corner of the closed eye. When they open their eyes, the drop rolls in — no fight needed.
• For older children (5+), sitting, looking up, pulling the lower lid down gently, and placing the drop into the lower pouch works well.
• Don’t chase a moving target. Hold the bottle close (without touching) and place a single drop — you only need one.
• Reward and routine matter more than you’d think. Morning and bedtime drops become part of the day quickly once established.

School and childcare — allergic conjunctivitis is not contagious

This point is worth making clearly, because it’s one of the most common misunderstandings:

• Allergic conjunctivitis is not infectious. Your child does not need to be excluded from school or childcare, and nobody is going to catch it from them.
• A classroom teacher who’s unfamiliar with atopic eye disease may still send your child home. If this happens, ask for a note to be kept on file — or we can provide one.
• The giveaway that this is not an infection: itch rather than pain; clear rather than thick coloured discharge; both eyes rather than one; a chronic or recurrent pattern rather than a 1-week acute episode.

Contact lens wearers

A few points if you wear contact lenses:

• Allergic conjunctivitis and contact lenses don’t mix well. If you’re having a bad allergy period, give the lenses a break and wear glasses — lenses trap allergen against the cornea and often provoke a worse reaction.
• Preservative choice matters. Benzalkonium chloride (in many standard eye drops) accumulates on soft contact lenses and can irritate. If you need to use drops with your lenses in, preservative-free unit-dose formulations are worth the extra cost.
• Lens hygiene is non-negotiable. Chronic allergic conjunctivitis increases the risk of a lens-related infection. Never rinse lenses with tap water, always use fresh solution, and replace the lens case regularly.
• Giant papillary conjunctivitis — a variant where large papillae develop on the inside of the upper lid from the mechanical rubbing of a contact lens. Presents as lens intolerance, ropy mucus, and worsening itch with lens wear. Treatment starts with stopping the lens for a period; dual-action drops help; a change of lens type is often needed afterwards.

Pregnancy

Topical eye drops have minimal systemic absorption, so the options are generally safer in pregnancy than systemic medication. A reasonable approach:

• Cold compresses and preservative-free artificial tears — safe throughout pregnancy and a useful first move
• Olopatadine and ketotifen eye drops — limited human data, but topical absorption is minimal and they are generally considered acceptable when needed
• Sodium cromoglycate drops (where available) — long-standing safety record
• Avoid decongestant “red-eye” drops
• Oral antihistamines — loratadine and cetirizine have the most reassuring data; discuss with us

When to come in

Allergic conjunctivitis usually doesn’t need same-day assessment, but please book a visit if:

• Standard over-the-counter drops aren’t settling symptoms after 2 weeks of consistent use
• Symptoms are only in one eye and persisting (one-sided problems deserve a look)
• You’re waking with thick coloured discharge that genuinely sticks the lids together, rather than mild crusting — this raises the possibility of a superimposed infection
• Vision has changed — blurring that doesn’t clear with a blink, trouble seeing in bright light beyond mild squinting, or seeing halos
• Your child is rubbing hard enough to be hurting themselves, or has developed photophobia
• You wear contact lenses and symptoms are worsening with lens wear

The Singapore context — schemes that help

• Healthier SG Chronic Tier — enrolled patients can access chronic-disease consultations and some medications at subsidised rates
• Community Health Assist Scheme (CHAS) — means-tested subsidies for consultations and selected medications at participating GP clinics
• MediSave — usable for chronic disease consultations, up to the annual withdrawal limit

Allergic conjunctivitis often sits under the broader “allergic rhinitis and its impact on asthma” umbrella for chronic-care purposes — if you’re enrolled with us for rhinitis, eye symptoms are reviewed and managed within that plan.

Get in touch

Joo Chiat — 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952

Punggol — 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589

Email — admin@ktmc.sg

References

Guidelines and reviews

• Bousquet J, Schünemann HJ, Togias A, et al. Next-generation Allergic Rhinitis and Its Impact on Asthma (ARIA) guidelines for allergic rhinitis based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) and real-world evidence. J Allergy Clin Immunol. 2020;145(1):70-80. (Covers allergic rhinoconjunctivitis together.)
• Dupuis P, Prokopich CL, Hynes A, Kim H. A contemporary look at allergic conjunctivitis. Allergy Asthma Clin Immunol. 2020;16:5. doi.org/10.1186/s13223-020-0403-9
• American Academy of Ophthalmology. Preferred Practice Pattern — Conjunctivitis. 2023 update. aao.org

Dual-action eye drops

• Abelson MB, Gomes P, Crampton HJ, Schiffman RM, Bradford RR, Whitcup SM. Efficacy and tolerability of olopatadine 0.2% in the treatment of allergic conjunctivitis. Curr Med Res Opin. 2007;23:1221-1232.
• Greiner JV, Mundorf T, Dubiner H, et al. Efficacy and safety of ketotifen fumarate 0.025% in the treatment of seasonal allergic conjunctivitis. Acta Ophthalmol Scand. 2003;81(5):495-504.

National programmes

• Ministry of Health, Singapore. Healthier SG and Chronic Tier information. healthiersg.gov.sg
• Community Health Assist Scheme. chas.sg

This information is for general education only and is not a substitute for medical advice. Allergic conjunctivitis management should be individualised to your symptom pattern, triggers, and any coexisting conditions — please speak with our team. v1.0 · April 2026 · Review due April 2028.