Conjunctivitis, allergic

Page last reviewed: 13/07/2011

Conjunctivitis is inflammation (swelling) of the conjunctiva. The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of the eyeball and the inner surfaces of the eyelids.

There are three different types of conjunctivitis, each with a different cause. The three types are:

  • irritant conjunctivitis
  • infective conjunctivitis
  • allergic conjunctivitis

Irritant conjunctivitis

Irritant conjunctivitis occurs when an irritant, such as chlorine (a chemical that is often used to purify water) or an eyelash, gets into the eyes and makes them sore. Rubbing the eyes can make the condition worse. The conjunctivitis should settle once the irritant is removed. If the eyes are very red and painful, medical attention should be sought immediately.

Infective conjunctivitis

Infective conjunctivitis is caused by a virus, bacteria or a sexually transmitted infection (STI), such as chlamydia or gonorrhoea. The most common symptoms include reddening and watering of the eyes, and a sticky coating on the eyelashes.

Allergic conjunctivitis

Allergic conjunctivitis occurs when the eyes come into contact with an allergen. An allergen is a substance, such as pollen or animal fur, that makes the immune system (the body's defence system) react abnormally. This causes irritation and inflammation, known as an allergic reaction. Allergic conjunctivitis causes itchy, swollen eyes.

There are four main types of allergic conjunctivitis:

  • seasonal allergic conjunctivitis
  • perennial allergic conjunctivitis
  • contact dermatoconjunctivitis
  • giant papillary conjunctivitis

These are caused by different allergens and may have slightly different symptoms.

How common is allergic conjunctivitis?

Allergic conjunctivitis is responsible for 15% of all eye-related problems that are recorded in GP surgeries. There are four to five cases of allergic conjunctivitis for every 1,000 people every year.

Half of all cases of allergic conjunctivitis are seasonal allergic conjunctivitis, which is commonly caused by grass pollen.

If seasonal or perennial allergic conjunctivitis also includes other symptoms, such as sneezing and an itchy nose, this could be hay fever, which affects around 20% of people in Ireland. See Hay fever for more information.

Giant papillary conjunctivitis is experienced by 1-5% of people using soft contact lenses and 1% of people using hard contact lenses.

Outlook

Seasonal and perennial allergic conjunctivitis can interfere with day-to-day life because they are usually triggered by common allergens, such as pollen. However, they can usually be managed effectively with medication, such as antihistamines.

Contact dermatoconjunctivitis and giant papillary conjunctivitis are usually caused by eye drops or contact lenses. Once the cause is identified and avoided, the symptoms usually clear up. However, it may be necessary to see an ophthalmologist (a medical doctor who specialises in eye conditions), who can provide advice about any further treatments that are needed.

Glossary

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

 

Page last reviewed: 13/07/2011

The symptoms of allergic conjunctivitis usually affect both eyes. Your symptoms can either:

  • appear very suddenly, often immediately after coming into contact with an allergen (a substance that you are allergic to) or
  • develop 24-48 hours after you have come into contact with the allergen

Main symptoms

If you have allergic conjunctivitis, you may experience some of the following symptoms:

  • Itchy eyes: this is the main symptom of allergic conjunctivitis. 
  • Red eyes: this happens as a result of the irritation and widening of the tiny blood vessels in your conjunctiva (the thin layer of cells inside your eyelids and over the white part of your eyes).
  • Watering eyes: the conjunctiva contains thousands of cells that produce mucus and tiny glands that produce tears. Irritation causes the glands to become overactive, causing them to produce more water than usual.
  • Swollen eyelids.
  • Soreness and a slight burning sensation: your eyes may feel sore or you may feel a slight burning sensation. They may also be slightly sensitive to light (mild photophobia).

The four types of allergic conjunctivitis are described in more detail below.

Seasonal allergic conjunctivitis

Seasonal or intermittent allergic conjunctivitis affects both eyes and occurs at a particular time of the year. For example, your symptoms may only appear in spring.

If you have seasonal allergic conjunctivitis, you may also experience allergic rhinitis (an allergic reaction that affects the nose). This can cause other symptoms, including:

  • a runny or blocked nose
  • sneezing
  • an itchy nose

Perennial allergic conjunctivitis

Perennial or persistent allergic conjunctivitis occurs throughout the year. It affects both eyes and you often experience symptoms when you wake up in the morning. You may also experience allergic rhinitis.

Contact dermatoconjunctivitis

In addition to the main symptoms above, contact dermatoconjunctivitis also causes allergic dermatitis of your eyelids. This means that the allergic reaction causes inflammation (swelling) of your eyelids, which makes them:

  • red
  • cracked
  • dry
  • sore

Giant papillary conjunctivitis

If you have giant papillary conjunctivitis, your symptoms will progress slowly. As well as the main symptoms above, you will also have very small spots on the inside of your upper eyelid.

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Unusual symptoms

Conjunctivitis can sometimes be confused with other eye conditions, such as iritis (inflammation of the iris, the coloured part of your eye). Unusual symptoms that are not normally caused by conjunctivitis include:

  • moderate to severe pain in your eyes
  • photophobia (sensitivity to light)
  • disturbed vision
  • intense redness in one or both of your eyes

Contact your GP immediately if you experience any of these symptoms. If this is not possible, visit your nearest accident and emergency (A&E) department.

Page last reviewed: 13/07/2011

Allergic conjunctivitis is caused when your eyes come into contact with an allergen. An allergen is a particular substance that causes your immune system (the body's defence system) to react abnormally. This is known as an allergic reaction.

Allergic reaction

In allergic conjunctivitis, the allergic reaction occurs in the conjunctiva. The conjunctiva is the transparent membrane (thin layer of cells) that covers the white part of your eyeballs and the inner surfaces of your eyelids. The allergic reaction triggers the symptoms of allergic conjunctivitis, such as itchy, swollen eyes. 

Seasonal and perennial conjunctivitis

Seasonal and perennial allergic conjunctivitis are usually caused by:

  • pollen from grass, trees or flowers
  • dust mites
  • flakes of dead animal skin

Seasonal and perennial allergic conjunctivitis are more common among people who also have other allergies, such as asthma (a condition that affects the lungs).

They also often occur with allergic rhinitis (an allergy that affects the nose, causing sneezing and a blocked or runny nose). 

Seasonal allergic conjunctivitis is most commonly caused by grass pollen. When it occurs with allergic rhinitis, it is known as seasonal allergic rhinitis or hay fever.

Contact dermatoconjunctivitis

Contact dermatoconjunctivitis is most commonly caused by eye drops, but it can also be caused by:

  • make-up (cosmetics)
  • chemicals

Giant papillary conjunctivitis

Giant papillary conjunctivitis is caused by:

  • contact lenses
  • stitches (sutures) used in eye surgery
  • a prostheses (artificial) part of the eye that is fitted during eye surgery

Giant papillary conjunctivitis is estimated to affect 1-5% of people who use soft contact lenses and 1% of people who use hard contact lenses. 

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

 

Page last reviewed: 13/07/2011

There is no procedure or test to confirm allergic conjunctivitis. Your GP will usually be able to make a diagnosis by assessing your symptoms and examining your eyes. If you have allergic conjunctivitis, you will usually have itchy and inflamed (swollen) eyes.

Your GP will also ask about any other symptoms that you may have. For example, if you have allergic conjunctivitis that is caused by pollen, you may also have a runny nose or be sneezing a lot.

Your symptoms can be easily confused with a different type of conjunctivitis, such as irritant or infective conjunctivitis. These have different causes and will be treated differently. In most cases, describing how your conjunctivitis started will indicate to your GP which type of conjunctivitis you have:

  • Irritant conjunctivitis is caused by an irritant, such as an eyelash getting into your eye. 
  • Infective conjunctivitis is caused by an infection, for example after being in close contact with someone who is infected.
  • Allergic conjunctivitis is caused by an allergen (a substance that you are allergic too, such as pollen).

Other conditions

If you have any unusual symptoms such as severe pain or sensitivity to light, you may have a different eye condition. In this case, it is very important to seek medical assistance immediately, either by contacting your GP or visiting your nearest accident and emergency (A&E) department.

If you experience unusual or severe symptoms, they may be a sign of a more serious condition. Your GP will need to rule out these conditions as part of your diagnosis, otherwise they may cause complications.

Other eye conditions that you may have include:

  • acute glaucoma: a rare form of glaucoma (an eye condition that affects your vision) and causes a painful build-up of pressure in your eye
  • keratitis: where your cornea (the clear layer at the front of the eye) becomes inflamed (swollen), leading to the formation of ulcers (open sores)
  • iritis: a type of uveitis (inflammation of the middle layer of your eye) that causes pain, headaches and watery eyes

Referral

If your conjunctivitis symptoms are severe or get worse, your GP may refer you to an ophthalmologist (a specialist in eye conditions).

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Page last reviewed: 13/07/2011

Your treatment will depend on which type of allergic conjunctivitis you have. However, some self-help methods can ease your symptoms.

Self-help

If you have allergic conjunctivitis, you can follow the guidelines below to treat your condition at home:

  • Remove your contact lenses. If you wear contact lenses, take them out until all the signs and symptoms of the conjunctivitis have gone. If you have glasses, wear them instead.
  • Do not rub your eyes, even though your eyes may be itchy. Rubbing them can make your symptoms worse.
  • Place a cool compress over your eyes. Wetting a flannel with cool water and holding it over your eyes will help ease your symptoms.
  • Avoid exposure to the allergen, if possible. For advice on avoiding allergens.

Seasonal and perennial allergic conjunctivitis

If you have seasonal or perennial conjunctivitis, you may be prescribed the following medicines:

  • antihistamines
  • mast cell stabilizers
  • corticosteroids

These are described in more detail below.

Antihistamines

If your allergic conjunctivitis requires rapid relief, your GP will probably prescribe a medicine known as an antihistamine.

Antihistamines work by blocking the action of the chemical histamine, which the body releases when it thinks it is under attack from an allergen. This prevents the symptoms of the allergic reaction from occurring.

Antihistamine eye drops

You may be prescribed antihistamine eye drops, such as:

  • azelastine (not suitable for children under four years of age)
  • emedastine (not suitable for children under three years of age)
  • ketotifen (not suitable for children under three years of age)
  • antazoline with xylometazoline (Otrivine-Antistin, not suitable for children under 12 years of age)

Antazoline with xylometazoline (Otrivine-Antistin) is also available over the counter from pharmacies without prescription. Always follow the manufacturer's instructions.

Warnings and side effects

If you wear contact lenses, stop wearing them while you are using eye drops. Do not wear them again until 24 hours after you stop using the eye drops and your symptoms have completely cleared up.

If you are pregnant or breastfeeding, some antihistamine eye drops may not be suitable. Visit your GP to find out which ones you can use. 

If you have been prescribed eye drops, your vision may become blurred shortly after using them. Do not drive or operate machinery immediately after using eye drops. Always make sure that your vision is clear before driving or operating machinery.

Eye drops may cause a stinging or burning feeling in your eye. However, this should not last long.

Oral antihistamines

You may be prescribed an antihistamine to take orally (by mouth), such as:

  • cetirizine
  • fexofenadine
  • loratadine

You will usually only have to take an oral antihistamine once a day.

Warnings and side effects

If possible, oral antihistamines should not be taken if you are pregnant or breastfeeding. If you are pregnant, visit your GP who may prescribe loratadine or chlorphenamine. If you are breastfeeding, your GP may prescribe loratadine or cetirizine.

Although new antihistamines should be non-sedating (not make you drowsy), they may still have a sedating effect. This is likely to be increased if they are taken at high doses or if you drink alcohol while you are taking antihistamines.

If you are taking antihistamines for the first time, avoid driving or operating machinery until you know how the medicine affects you.

Mast cell stabilizers

Mast cell stabilizers are an alternative type of medicine that may be prescribed to treat allergic conjunctivitis. Unlike antihistamines, they will not provide rapid relief from your symptoms, but they are more effective at controlling your symptoms over a longer period of time.

It may take several weeks to feel the effects of mast cell stabilizers. You may also be prescribed an antihistamine to take at the same time so that your symptoms can be controlled while you are waiting for the mast cell stabilizer to take effect.

Mast cell stabilizers that are commonly prescribed in the form of eye drops include:

  • lodoxamide
  • nedocromil sodium
  • sodium cromoglicate 

Warnings and side effects

If you wear contact lenses, stop wearing them while you are using eye drops. Do not wear them again until 24 hours after you stop using the eye drops and your symptoms have completely cleared up.

If you have been prescribed eye drops, your vision may become blurred shortly after using them. Do not drive or operate machinery straight after using eye drops. Make sure that your vision is clear before driving or using machinery.

All of these eye drops may cause slight burning or stinging. This is most common with lodoxamide and affects 13% of people using it. Nedocromil sodium may also cause an unpleasant taste in your mouth immediately after using the eye drops. 

Mast cell stabilizers should be avoided if you are pregnant or breastfeeding. Speak to your GP if you feel that they are necessary.

Corticosteroids

If your symptoms of allergic conjunctivitis are particularly severe and a diagnosis has been confirmed, you may be prescribed a short course of oral corticosteroids (steroids).

Corticosteroids are a type of medication that contain hormones (powerful chemicals that have a wide range of effects on the body). You may be prescribed a short course to take for three to five days. However, these are not usually prescribed unless absolutely necessary.

Contact dermatoconjunctivitis

If your contact dermatoconjunctivitis is caused by an allergic reaction to the eye drops that you were using, you may be advised to stop using them and to find an alternative. Discuss the eye drops with your GP.

You may to be referred to an ophthalmologist (a specialist in eye conditions) to confirm your diagnosis and recommend a suitable alternative treatment. This is likely to be at the eye department of your local hospital.

Giant papillary conjunctivitis

As giant papillary conjunctivitis is usually caused by contact lenses, the symptoms often clear up after you stop wearing them. The spots that form on the inside of your upper eyelid may last slightly longer.

Visit your optometrist (previously known as an ophthalmic optician) to discuss further treatment. They may discuss:

  • changing the type of contact lenses you use
  • prescribing mast cell stabilizers (see above) to prevent your symptoms reoccurring
  • effective hygiene measures to ensure that you are looking after your eyes and contact lenses safely

If you develop giant papillary conjunctivitis as a result of recent eye surgery, you will be immediately referred to an ophthalmologist. This is to ensure that your eyes can be carefully monitored and the most effective treatment given.

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Hormones
Hormones are groups of powerful chemicals that are produced by the body and have a wide range of effects.

Page last reviewed: 13/07/2011

Seasonal and perennial allergic conjunctivitis

If you have seasonal or perennial allergic conjunctivitis, it is very rare to experience any serious complications. However, you may find your reoccurring symptoms frustrating. For example, if your conjunctivitis is caused by pollen, you may find it difficult to go outside during the spring and summer months without triggering your symptoms.

This type of allergic conjunctivitis can affect your daily life and could make it difficult for you to concentrate at work or school, particularly if your eyes are severely irritated. Although this can affect your quality of life, it should not cause any long-term health problems.

Dermatoconjunctivitis and giant papillary conjunctivitis

As well as affecting your daily life, dermatoconjunctivitis and giant papillary conjunctivitis may cause more serious complications. For example, in rare cases dermatoconjunctivitis and giant papillary conjunctivitis can cause a condition called keratitis.

Keratitis is where your cornea (the clear layer at the front of your eye) becomes inflamed (swollen). This can be painful and make your eyes sensitive to light (photophobia). Sometimes, ulcers (open sores) form on the cornea. If the ulcers scar your cornea, your vision may be permanently damaged.

Contact your GP immediately if you experience any unusual symptoms or visit your nearest accident and emergency (A&E) department.

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Page last reviewed: 13/07/2011

You can try to prevent allergic conjunctivitis by avoiding the allergen that causes your symptoms (the substance that you are allergic to).

For example, if you know that a particular type of make-up causes allergic conjunctivitis, find an alternative.

Avoiding the allergen is not always possible, but the advice below may help.

Avoiding pollen 

If you have seasonal or perennial allergic conjunctivitis that is caused by pollen, you can reduce your exposure to pollen by:

  • keeping doors and windows closed when the pollen count is high
  • avoiding going out at certain times of the day when the pollen count is at its highest, such as in the mornings and evenings
  • wearing wraparound sunglasses when you are outside
  • fitting a pollen filter to your car

Avoiding house dust mites

In most cases, your medication should help control your allergy to house dust mites. If you are still affected by allergic conjunctivitis and allergy testing has confirmed that it is caused by house dust mites, some medical experts recommend the following measures:

  • Fit mattresses with covers that house dust mites cannot get through.
  • Use synthetic (man-made) pillows and duvets.
  • Keep soft toys off the bed.
  • Wash all bedding and soft toys at least once a week.
  • Choose wooden or hard floor surfaces instead of carpets.
  • Choose blinds that can be wiped clean instead of curtains.
  • Wipe surfaces regularly with a clean, damp cloth.

Some of these measures may be expensive and there is currently little evidence to confirm their benefit. 

Glossary

Allergy
Allergy is the term used to describe an adverse (bad) reaction that the body has to a particular substance.

Allergen
An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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