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Jun 22, 2021
3 min read

Pink eye or allergies: how to tell the difference

It can be tough to know whether you have pink eye or allergies—but there are differences between the two. Pink eye is caused by inflammation of the lining of the eyeball and eyelid, also called the conjunctiva. It may be due to bacteria, viruses, or chemicals, in addition to allergies. Knowing the cause is important because the treatment depends on the type of pink eye.

Disclaimer

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

It’s happened to many of us—you notice that your eyes are red and watery, and you wonder, “Is this pink eye or allergies?”. If you’ve ever awoken to find your eyelashes stuck shut from its telltale discharge, or allergy season has people asking why you look like you’ve been crying, you know what we are talking about.

Pink eye (or conjunctivitis) can have several distinct causes, and to treat it, it’s important to determine which kind you have.

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What is pink eye?

Pink eye is also known as conjunctivitis because it is due to inflammation of the conjunctiva.  The conjunctiva is a thin layer of tissue covering the inside of the eyelid and the white part of the eye. It has tiny blood vessels that can become inflamed and swollen, making the normally clear conjunctiva look pink. Conjunctivitis can occur in one or both eyes, making them red, watery, or itchy. This eye condition may be caused by bacteria (such as streptococcus or staphylococcus), viruses (such as adenovirus), or some other type of irritant (chemicals, etc.) (Ryder, 2020). 

What are allergies?

Allergies occur when your immune system responds to allergens, which are otherwise harmless substances in our environment. Allergens can include things like pollen, pet dander, dust mites, and certain foods. For some people, these allergens cause allergic rhinitis leading to the typical symptoms of allergies—sneezing, runny nose, nasal congestion, etc. Certain allergens can also cause allergic reactions in the eye, characterized by red, itchy, watery eyes that may feel irritated or painful (Akhouri, 2021). 

Pink eye infection or allergies?

It can be challenging to know why your eye is pink and bothering you. Pink eye has multiple potential causes, and red, watery, irritated eyes are common signs in most types of pink eye—but each type also has some distinguishing features.

Bacterial conjunctivitis

Bacterial pink eye infections (conjunctivitis) tend to have more discharge and crusting, usually yellowish or yellow/green. Some people find that their eyelids are stuck together upon waking up in the morning. Bacterial conjunctivitis can occur in one or both eyes and may be accompanied by blurred vision and eye irritation. You can catch bacterial pink from others if you come in contact with their eye discharge—but it is not nearly as contagious as viral pink eye (Ryder, 2020). 

Viral conjunctivitis

Viral pink eye is highly contagious. It does not have as much discharge as bacterial pink eye, but your eyelids can still get crusty and stuck together with a viral infection. The eye discharge is watery or sometimes whitish and ropey; some people also experience eye irritation and light sensitivity, more so than itchy eyes (Ryder, 2020). 

Viral conjunctivitis can occur in one or both eyes. Often, it starts in one eye and spreads to the other. Most people with viral conjunctivitis have had a recent cold, exposure to someone with a cold, or close contact with someone at high risk for cold—like a child in school or daycare (Ryder, 2020). 

Allergic conjunctivitis

Eye allergies (allergic conjunctivitis) almost always happen in both eyes. The predominant eye symptoms of allergic conjunctivitis are itchy, watery eyes. It may also be accompanied by other allergy symptoms, including nasal congestion and sneezing. Your eyelids may swell, and your eyes can sometimes be sensitive to light (Ryder, 2020). 

Chemical conjunctivitis

Chemical conjunctivitis occurs when an irritant comes into contact with your eye and only affects the eye involved. Your eye may become very irritated, painful, light-sensitive, and watery. However, itchy eyes are not usually a major symptom. 

Treatment and prevention

If you think you may have pink eye, see your healthcare provider or an ophthalmologist (eye doctor), who can diagnose which kind of conjunctivitis you have and advise you on treatment.  

You can clear up pink eye from bacterial infections with antibiotic eye drops most of the time. Viral pink eye won’t respond to antibiotics, but artificial tears can help treat your symptoms. Viral conjunctivitis is very contagious, and you need to be sure to wash your hands anytime you rub your eyes and avoid close contact with others. Don’t share towels, pillows, cosmetics, etc., with other people, or you’ll risk passing the infection on to them. If you wear contact lenses, remove them and use your glasses until the infection resolves.

For pink eye caused by allergies, medications like antihistamines, corticosteroids, and artificial tears—many are available over the counter—can help treat your pink eye and allergy symptoms overall. 

To prevent allergy symptoms, avoid the offending allergens (whenever possible), frequently wash your bedsheets and pillowcases, and clean/vacuum your home regularly to eliminate irritants such as dust mites and dander. If you have seasonal allergies, use allergy medications when needed to prevent your symptoms from getting worse.

References

  1. Akhouri, S. & House, S.A. (2021). Allergic rhinitis. [Updated Mar 31, 2021]. In: StatPearls [Internet]. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK538186/
  2. Ryder, E.C. & Benson, S. (2020). Conjunctivitis. [Updated Aug 11, 2021] In: StatPearls [Internet]. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK541034/