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You’ve got red, swollen, watery, itchy eyes and are not sure what is causing your symptoms. Is it what is commonly called pink eye? Or do you have allergies? Continue reading to learn more about pink eye and allergies and how to tell the difference between the two. (You should always get medical advice, diagnosis, and treatment, but it doesn’t hurt to be informed).

What is conjunctivitis?

Conjunctivitis is an irritation and inflammation of the conjunctiva. The conjunctiva is a clear, thin membrane that covers the front, white surface of the eye and also lines the inner surface of the upper and lower eyelids. It keeps the eyes lubricated and protects them from dust, debris, and infectious organisms. When the conjunctiva becomes inflamed, it causes symptoms such as red eyes, swelling, itchy eyes, burning, excessive tearing, green discharge, watery discharge from the eyes, light sensitivity, and blurred vision. 

There are three main types of conjunctivitis: bacterial, viral, and allergic conjunctivitis.

What is pink eye?

Pink eye is the commonly used term for an infection of the conjunctiva. Both bacteria and viruses can cause a conjunctival infection. Technically speaking, only viral conjunctivitis is called pink eye. However, in common usage, people don’t usually differentiate between bacterial and viral infections, and both are called pink eye.

Many of the viruses that cause pink eye are viruses that also cause the common cold. Therefore, pink eye is sometimes called an “eye cold.” Several different types of bacteria can also cause symptoms of pink eye. For example, the bacteria that cause strep throat can also cause pink eye. Some other types of bacterial infections are serious and should be evaluated and treated promptly. Less commonly, certain fungi and parasites can cause infection and inflammation of the conjunctiva. 

Bacterial and viral pink eye is a highly contagious type of conjunctivitis. It spreads easily from person to person and is, therefore, common among young children in daycare centers and schools. It is important to differentiate clinically whether the cause is due to a viral or bacterial agent since the treatment will be different for each one. 

What is allergic conjunctivitis?

Allergic conjunctivitis is a very common type of eye allergy. It causes symptoms that are similar to pink eye. However, the inflammation of the conjunctiva occurs due to contact of the eye with allergens such as pet dander, dust, pollen, smoke, or with long-term use of contact lenses. Allergic conjunctivitis may be related to seasonal allergies and hay fever. Unlike viral and bacterial infections, allergic conjunctivitis isn’t contagious. 

What’s the difference between pink eye and allergies?

To gain an in-depth understanding of infectious pink eye vs. eye allergies, let’s take a look at different aspects of these two conditions. Both are types of conjunctivitis, but their prevalence, risk factors, causes, symptoms, diagnosis, treatment, and prevention can be different.

Prevalence

According to the CDC, around 6 million Americans contract conjunctival infections (pink eye) each year. Viral conjunctivitis is more common in adults. In children, however, fifty to seventy-five percent of conjunctival infections are bacterial pink eye.

An estimated 50 million Americans suffer from allergies each year, however not all allergies affect the eyes. Seasonal allergies are responsible for around 95% of allergic conjunctivitis.

Risk factors

The most important risk factor for bacterial or viral pink eye is coming in contact with someone who has an infection. Direct contact with an infected person and the transfer of germs from hand to eye can cause pink eye. Also, poorly fitting or dirty contact lenses increase the risk of pink eye.

Risk factors for allergic conjunctivitis include a family history of allergies and asthma. Children are also more likely to have allergic conjunctivitis. 

Causes

As noted above, bacterial or viral conjunctivitis (pink eye) is caused by infectious organisms. Allergic conjunctivitis, on the other hand, is caused by exposure to environmental irritants and allergens.

Symptoms

Common symptoms of infectious pink eye include redness, watery eyes, green discharge, and formation of a crust on the eyelids, causing stickiness of the eyelid to the point that it may be difficult to open the eyes in the morning. Infectious conjunctivitis can have systemic symptoms including adenopathy, fever, pharyngitis, and upper respiratory tract infection.

Symptoms of allergic pink eye include red eyes, itchy eyes, irritation, swollen eyelids, watery discharge, and sensitivity to light. The infection can start in one eye and spread to the other eye.

An important way to tell the difference between bacterial pink eye and allergic pink eye is that people with allergic pink eye symptoms often have other allergy symptoms such as sneezing, coughing, runny nose, and scratchy throat. Also, the discharge in allergic conjunctivitis tends to be watery, while the discharge from an infection is usually a yellow or green discharge.

Symptoms of allergic or infectious pink eye that need to be evaluated and treated immediately include blurred vision, loss of vision in one eye, and swelling or redness of the face near the eyes.

Diagnosis

A primary care physician, optometrist, or ophthalmologist (eye doctor) can diagnose bacterial or viral pink eye vs. allergic conjunctivitis based on a patient’s history, symptoms, and exam. The doctor may examine the eyes with an instrument that shines a light and magnifies the structures in the eye to see if anything is causing the inflammation. 

Sometimes, a sample of the cells lining the eye is sent to the laboratory for culture to identify which virus or bacteria is causing the infection. This is typically only necessary in people with a severe case of pink eye that is not responding to the usual treatments.

Treatment

You should never attempt to self-treat an eye condition. Always rely on medical advice, diagnosis, or treatment from a healthcare professional. 

In general, pink eye caused by a virus will run its course and clear on its own. Eye drops such as artificial tears and cold compresses can provide symptom relief. Antibiotic eye drops cannot treat viral infections. Sometimes, antiviral medications may be required, especially if the symptoms worsen or do not improve after a week to 10 days. 

Some mild bacterial infections of the conjunctiva clear on their own. However, a doctor may prescribe treatment with an antibiotic ointment or eye drops for pink eye caused by bacteria.

Allergic conjunctivitis can be treated with both over-the-counter and prescription allergy medicines. Oral antihistamines and antihistamine eye drops can help relieve symptoms. Steroids and immunotherapy may be required in more severe cases of pink eye caused by allergies.

Prevention

The easiest way to prevent infectious pink eye is to wash your hands regularly and avoid touching your eyes. When you rub your eyes with dirty hands, you can transfer bacteria or viruses to the eyes which cause pink eye. It’s also important to throw out old eye makeup like mascara and eyeliner. Clean your contact lenses as advised by your optometrist and do not use them for longer than recommended. Last but not least, you should go for regular checkups to ensure any eye health problems are caught and treated early.

Allergic conjunctivitis can be prevented by limiting exposure to seasonal allergens such as pollen. Also, you should practice good hand hygiene after handling animals. Some antihistamines medications can be used to prevent allergic conjunctivitis as well.

Now that you know the difference between infectious conjunctivitis of the eye (viral or bacterial pink eye) and allergies, a last word of advice: never treat symptoms of conjunctivitis, allergic or infectious, without medical advice. Do not use someone else’s prescription treatment, and seek care from a doctor if your pink eye or allergy symptoms do not improve with a few days of home treatment.

References:

1. https://www.aao.org/eye-health/diseases/pink-eye-conjunctivitis

2. https://www.cdc.gov/conjunctivitis/index.html

3. https://jamanetwork.com/journals/jama/article-abstract/1758756

4. https://acaai.org/news/facts-statistics/allergies

5. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/ocular-allergies?sso=y