Allergic Conjunctivitis

Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

See also: Allergic Conjunctivitis written for patients

The term conjunctivitis refers to inflammation of the conjunctiva, and allergic conjunctivitis occurs when this is caused by an allergic reaction. This is most commonly a type 1 hypersensitivity reaction and it gives rise to seasonal or perennial allergic conjunctivitis.[1]

Other types of allergic conjunctivitis are outlined here but their management is generally guided by an ophthalmology team. If you are managing a non-allergic conjunctivitis, you may find the following separate articles helpful: Eye Drugs - Prescribing and Administering (notes about eye drop allergies); Conjunctivitis (viral and less common types of conjunctivitis); Bacterial Conjunctivitis; Ophthalmia Neonatorum (conjunctivitis in the newborn); Conjunctival Problems (including trauma, lesions, degenerative conditions, etc).

Although allergic conjunctivitis is generally not considered to be a 'serious' condition by patients, it can have a significant impact on the patient's quality of life during the acute episode and can cause significant distress and anger if it is not resolved.[2, 3]

  • Allergies are thought to affect about 20% of the population and, of these, about 20% of individuals experience eye problems.[3]
  • Over 50% of patients who seek treatment for allergies present with ocular symptoms.[4]Allergic conjunctivitis is the cause of around 15% of all eye problems presenting in general practice.[1]
  • Seasonal allergic conjunctivitis and perennial allergic conjunctivitis are often associated with a family history of atopy (asthma, eczema or rhinitis).

Vernal keratoconjunctivitis occurs mainly in hot climates and presents more often in young males (see 'Vernal conjunctivitis', below).

Allergic conjunctivitis presents with an intense itch or a burning sensation, a feeling of grittiness in the eyes and mild photophobia.  The eyes are often watery and red.[5]

Ask about exposure to allergens and irritants - for example:

  • A history of contact with chemicals or eye drops.
  • A history with a seasonal time course.
  • A history of reaction to eye make-up.
  • Contact lens use and hygiene.
  • Occupational exposure to potential chemical irritants.

Ask about known allergies: 

  • Major - hay fever, asthma, atopic dermatitis, eczema.
  • Minor - idiopathic urticaria, non-hereditary angio-oedema, food allergies.


  • Bilateral red eyes are typical, often with a clear watery discharge.
  • Oedema in round swellings on the inside of the eyelid.
  • Lid swelling.
  • Conjunctival injection.
  • Skin irritation on the lids in contact dermatoconjunctivitis.
  • Wearers of contact lenses may report decreased lens tolerance and mucous discharge in giant papillary conjunctivitis.
  • Lid oedema.
  • Conjunctival chemosis with papillae which may be giant (>1 mm) in contact lens or prosthesis users.

The diagnosis is usually straightforward but other causes of uncomfortable, inflamed eyes must be considered:

The diagnosis is usually made on history and eye examination. This should include staining the eyes, testing acuity, checking the anterior chamber for clarity (as far as possible with a handheld ophthalmoscope) and everting the lids to look for foreign bodies and examining the underside of the eyelids.

Investigations and/or referral are only indicated if there is any doubt in the diagnosis. Investigations may include conjunctival swabs, skin prick testing, serum immunoglobulin E (IgE) and radioallergosorbent test (RAST).

There are six recognised types of allergic conjunctivitis: seasonal, perennial, drug-induced, contact lens-induced, vernal and atopic.[6]The first four are caused by type 1 hypersensitivity reactions: vernal and atopic conjunctivitis are addressed separately below:

Conjunctivitis due to type 1 hypersensitivity reactions

  1. Seasonal conjunctivitis (aka conjunctivitis associated with hay fever). The most common allergen is pollen. Grass pollens peak from May to August whereas tree pollens tend to peak on either side of this period, depending on the tree species involved. Individual patients may have multiple allergies, but their symptoms tend to recur at the same time each year.
  2. Perennial conjunctivitis, where symptoms occur throughout the year in response to various allergens such as animal dander and house dust mites. Symptoms may be worse in the mornings.
  3. Giant papillary conjunctivitis - common causes include contact lenses, and (broken) sutures and prostheses following eye surgery. This is the most severe form of contact lens-associated papillary conjunctivitis. It is seen in contact lens and prosthesis users. However, the widespread use of disposable contact lenses has reduced its incidence.
  4. Contact dermatoconjunctivitis which tends to arise in response to eye drops or cosmetics. It is characterised by a complete lack of response to antihistamines and mast cell stabilisers.

The management of allergic conjunctivitis is aimed at preventing the release of mediators of allergy, controlling the allergic inflammatory cascade and preventing ocular surface damage secondary to the allergic response.[3, 7]Many patients start medicating themselves of their own accord and go for help when basic measures have failed.[2]In milder cases, it is worth checking the following before considering drug treatment:

Non-pharmaceutical management[7]

  • Avoiding rubbing the eyes.
  • Using cool compresses, eye baths and preservative-free lubricants may be soothing.
  • Avoiding wearing contact lenses/prostheses until symptoms and signs resolve.
  • If lenses are essential, consider using daily disposable lenses.
  • Allergen avoidance is often tricky but should be the primary aim. Consider introducing air conditioning, reducing pet contact, and bedding change.
  • Artificial tears can be helpful in mild cases (they dilute the allergen).
  • Contact lenses should not be worn if conjunctivitis is present or during a course of topical therapy.

Pharmaceutical management[7]

  • Topical mast cell stabilisers - eg, sodium cromoglycate: mast cell stabilisers are recommended for use throughout a period of allergen exposure. Sodium cromoglycate is usually effective but the newer agents, lodoxamide and nedocromil, may be effective in those with an inadequate response to sodium cromoglicate.
  • Topical antihistamines (other than in contact dermatoconjunctivitis which is unresponsive to these). The topical ocular antihistamines, antazoline, azelastine, and emedastine provide rapid relief of the symptoms of allergic conjunctivitis. Azelastine seems to have additional mast cell stabilising properties.[4]Topical antihistamines are not appropriate for prolonged use (no longer than six weeks).
  • Combined antihistamine/vasoconstrictor drops - eg, antazoline with xylometazoline.
  • Diclofenac eye drops are also licensed for seasonal allergic conjunctivitis.
  • Oral antihistamines such as loratadine or chlorphenamine may be used. Oral antihistamines provide relief of symptoms and are particularly useful when there is associated allergic rhinitis. They can cause drowsiness, particularly the older compounds such as chlorphenamine, and patients need to be cautioned regarding this.
  • Topical corticosteroids (eg, betnesol) can be used if symptoms are very severe but there must be absolutely no doubt about the diagnosis.[8]Remember the risks of infections, including undiagnosed corneal herpes simplex or ocular herpes zoster, and of secondary glaucoma. Topical corticosteroids should never be given for an undiagnosed red eye, when visual acuity is impaired, or if there is a history of ocular herpes simplex infection. Long-term use is avoided because this can result in cataract, glaucoma, and severe bacterial or fungal infections involving the eyelid, conjunctiva, and cornea. There may be a role for intranasal corticosteroids which have been shown to reduce ocular symptoms.[9]
  • Oral steroids in a short (five-day) course may be used in severe cases where there is no doubt about the diagnosis. Ophthalmologists may use them in severe cases.[8]

Patients experiencing giant papillary conjunctivitis following surgery should be referred to the ophthalmologists. Also, consider referral where contact dermatoconjunctivitis is severe or where an alternative eye drop also needs to be prescribed (eg, for glaucoma).

Serious complications are very rare in the majority of cases of allergic conjunctivitis, but a severe allergic reaction can lead to corneal ulceration.

Prognosis is excellent with resolution over a variable time course.

This is an uncommon IgE and cell-mediated allergic condition, mainly affecting boys (usually after the age of 5) and young individuals (there is no gender bias post-puberty), living in warm conditions.[6]It rarely persists beyond the age of 25 years. Its incidence is decreasing among the white population but increasing among Asians. It is most common in Arabs and Afro-Caribbeans.

Vernal conjunctivitis may be seasonal or perennial, and is often more pronounced in the spring months.[6]

Think of this in patients not responding to conventional treatment.[1]A new grading system has recently been developed to indicate the severity of this disease, ranging from 0 (absence of symptoms and no therapy) to 4 (severe disease involving the cornea and needing pulsed high-dose topical steroid).[10]

Risk factors

  • Atopy (patient or family history in over 80% of cases).
  • Associated keratoconus (possible cause, possible effect) and other types of corneal malformations.

Suggestive symptoms[11]

  • Intense itching.
  • Thick ropey mucous discharge.


Look for:

  • Large cobblestone upper lid papillae (if these are very large, they may cause a mechanical ptosis).
  • Raised white mucoid nodules arranged around the limbus (margin) of the cornea.
  • Associated keratitis (in the form of little epithelial erosions, seen as tiny dots on slit-lamp examination with a fluorescein stain or in the form of an ulcer).


  • Refer suspected vernal conjunctivitis to ophthalmologists, as management is specialised and serious corneal complications can occasionally occur.[6]
  • Topical steroids may need to be added to conventional anti-inflammatory treatment.
  • Systemic therapy with steroids ± ciclosporin may sometimes be needed.
  • Aspirin may be of benefit in older children. 
  • Systemic antivirals may be added to the treatment regime if immunosuppressants are used, as these patients are vulnerable to herpes simplex keratitis.
  • Permanent relocation to a cooler climate is a very effective therapy for vernal conjunctivitis although, clearly, this is not practicable in many cases.

This is a relatively rare but potentially serious condition affecting mainly young individuals (onset: age 25-30 years) suffering from atopic dermatitis. Presentation can be similar to vernal conjunctivitis but the condition persists for years and is associated with significant visual morbidity secondary to keratoconus, presenile cataract and occasionally, retinal detachment.

Suggestive symptoms

  • Itching
  • Redness
  • Photophobia ± blurred vision.


Look for:

  • Red, thickened, scaly and occasionally fissured lids (lid eczema and blepharitis).
  • Cicatrisation of the conjunctiva in advanced cases.
  • Keratopathy (including keratoconus).
  • Evidence of concurrent infections such as herpes simplex virus (HSV) and microbial keratitis.
  • Unlike vernal conjunctivitis, the discharge tends to be watery.


Referral to ophthalmology, where the approach is similar to that for vernal conjunctivitis. This condition is associated with a higher rate of corneal scarring than vernal conjunctivitis and needs specialised care.[6, 12]

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Further reading & references

  • Chigbu DI; The management of allergic eye diseases in primary eye care. Cont Lens Anterior Eye. 2009 Dec 32(6):260-72. Epub 2009 Oct 30.
  • Bielory BP, Perez VL, Bielory L; Treatment of seasonal allergic conjunctivitis with ophthalmic corticosteroids: in Curr Opin Allergy Clin Immunol. 2010 Oct 10(5):469-77.
  • Owen CG, Shah A, Henshaw K, et al; Topical treatments for seasonal allergic conjunctivitis: systematic review and meta-analysis of efficacy and effectiveness. Br J Gen Pract. 2004 Jun 54(503):451-6.
  • Szczotka-Flynn LB, Pearlman E, Ghannoum M; Microbial contamination of contact lenses, lens care solutions, and their Eye Contact Lens. 2010 Mar 36(2):116-29.
  • Pollen Count Forecast
  1. Conjunctivitis - infective; NICE CKS, August 2012 (UK access only)
  2. Palmares J, Delgado L, Cidade M, et al; Allergic conjunctivitis: a national cross-sectional study of clinical Eur J Ophthalmol. 2010 Mar-Apr 20(2):257-64.
  3. Chigbu DI; The management of allergic eye diseases in primary eye care. Cont Lens Anterior Eye. 2009 Dec 32(6):260-72. Epub 2009 Oct 30.
  4. Williams PB, Crandall E, Sheppard JD; Azelastine hydrochloride, a dual-acting anti-inflammatory ophthalmic solution, Clin Ophthalmol. 2010 Sep 7 4:993-1001.
  5. Conjunctivitis - allergic; NICE CKS, August 2012 (UK access only)
  6. What sets vernal keratoconjunctivits apart form other allergic conditions, and how to create targeted treatments for it; Review of Ophthalmology, 2012
  7. Azari AA, Barney NP; Conjunctivitis: a systematic review of diagnosis and treatment. JAMA. 2013 Oct 23 310(16):1721-9. doi: 10.1001/jama.2013.280318.
  8. Bielory BP, Perez VL, Bielory L; Treatment of seasonal allergic conjunctivitis with ophthalmic corticosteroids: in Curr Opin Allergy Clin Immunol. 2010 Oct 10(5):469-77.
  9. Origlieri C, Bielory L; Intranasal corticosteroids: do they improve ocular allergy? Curr Allergy Asthma Rep. 2009 Jul 9(4):304-10.
  10. Sacchetti M, Lambiase A, Mantelli F, et al; Tailored approach to the treatment of vernal keratoconjunctivitis. Ophthalmology. 2010 Jul 117(7):1294-9. Epub 2010 Apr 10.
  11. The Wills Eye Manual
  12. Chen JJ, Applebaum DS, Sun GS, et al; Atopic keratoconjunctivitis: A review. J Am Acad Dermatol. 2013 Dec 13. pii: S0190-9622(13)01150-X. doi: 10.1016/j.jaad.2013.10.036.
Original Author:
Dr Colin Tidy
Current Version:
Dr Mary Lowth
Peer Reviewer:
Dr Helen Huins
Document ID:
1548 (v25)
Last Checked:
11 February 2014
Next Review:
10 February 2019

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

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