Conjunctivitis (Pink Eye): Causes, Symptoms, and Treatment

Reviewed by Dr. Richard Foxx, MD— Conjunctivitis, or “pink eye,” is a rather common condition marked by swelling in the outer membrane of the eye. It can affect the eye and eyelid, and can be unsightly and uncomfortable.

Inflammation of the conjunctiva, the thin membrane that lines the inside of the eyelid and the white of the eye, can cause the area to turn red or pink.

There are a number of causes of conjunctivitis, including highly contagious viral and bacterial infections. There is even a minor association between conjunctivitis and COVID-19.

Conjunctivitis (Pink Eye) Causes

There are four main causes of conjunctivitis:

• Viral infection
• Bacterial infection
• Allergies
• Environmental irritants

The exact cause of pink eye can be difficult to determine because symptoms sometimes overlap.

1. Viral Conjunctivitis

Most viral conjunctivitis cases are caused by an adenovirus, but they can also be caused by herpes-simplex, varicella-zoster, and other viruses, including the virus that causes COVID-19. Viral conjunctivitis is highly contagious and can result in outbreaks.

2. Bacterial Conjunctivitis

Various strains of bacteria can produce bacterial conjunctivitis. Potential bacterial pathogens include:

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis
• Chlamydia trachomatis
• Neisseria gonorrhoeae

These bacteria can spread very easily in certain settings, making them very contagious. This type of pink eye is more common in children, and the risk is highest between the months of December and April.

3. Allergic Conjunctivitis

Pink eye can also be an allergic reaction to any number of substances. Potential allergens that may lead to conjunctivitis include:

• Plant, tree, or grass pollen
• Dust mites
• Molds
• Animal/pet dander
• Medications
• Cosmetics

This form of pink eye is not contagious and generally occurs in allergy sufferers.

4. Irritant Conjunctivitis

Eyes can become irritated and symptomatic when they are exposed to environmental irritants. Pink eye caused by irritants is not contagious and can be treated rather quickly.

Common causes include:

• Smoke
• Dust
• Fumes
• Chemical vapor
• A foreign body in the eye, like an eyelash
• Chemical irritants (soap, shampoo, makeup, etc.)
• Wearing contact lenses longer than recommended or not cleaning them appropriately

Pink Eye Symptoms

Although pink eye is distinguished by how it makes the eye look and feel, there are some distinct features that may help you identify which type you have. General symptoms include:

• Pinkness/redness in the whites of the eyes
• Swelling of the conjunctiva or eyelid
• Increased tear production
• A sensation that something is in the eye/the urge to rub
• Itching/irritation/burning in the eye(s)
• Discharge (pus/mucus)
• Crusting of eyelids and/or lashes, particularly after sleep
• Discomfort wearing contact lenses (contacts may not stay in place or fit properly)

Below are some distinguishing features of the different types of pink eye.

Viral Conjunctivitis Symptoms

• May occur concurrently with a cold, the flu, or other viral respiratory infections
• Usually begin in one eye and may spread to the other within a few days
• More likely to feature watery discharge than thick discharge

Bacterial Conjunctivitis Symptoms

• More commonly associated with thick, discharge-like pus that can result in eyelids sticking together
• May occur alongside an ear infection

Allergic Conjunctivitis Symptoms

• Usually occur in both eyes
• Can lead to intense itching, tearing, and swelling in eyes
• May develop alongside other allergy symptoms like itchy nose, sneezing, scratchy throat, etc.

Irritant Conjunctivitis Symptoms

• Often include watery eyes and mucus discharge

Is There a Link between Pink Eye and COVID-19?

Because the eyes serve as an entry point for viral infections, pink eye and COVID-19 may have a relationship. There is work to suggest that a very small number of people infected with the virus develop pink eye as a symptom.

It should be noted that pink eye is not a standalone symptom of COVID-19, and a case of conjunctivitis does not mean you’ve been infected with the coronavirus causing COVID-19.

If you have noticed the onset of other symptoms like dry cough, shortness of breath, or high fever, visit your nearest testing center for a COVID-19 test. Pink eye, in most cases, is just that.

Current estimates suggest that one percent to three percent of people infected with COVID-19 may get pink eye. By comparison, 83% to 99% develop a fever, and 53% to 82% get a cough. Other research suggests that pink eye is more common in children and people with severe cases of COVID-19.

Natural Remedies for Conjunctivitis (Pink Eye)

The cause of pink eye will ultimately determine the treatment and whether a natural remedy will be effective. Viral and bacterial infections may be preventable, but treatment will almost always require either a prescription or an over-the-counter (OTC) antibiotic. The medications will be administered as eye drops or pills.

How long does conjunctivitis last? Most cases of viral or bacterial conjunctivitis will subside in about two weeks. If you’re patient, you could simply wait it out (and you will have to if it’s a viral infection).

During that time, however, you will have to be extremely diligent with your hygiene to prevent others from becoming infected and avoid re-infecting yourself. You will also have to be comfortable living with the irritating symptoms of pink eye. Natural treatments like a warm compress and OTC eye drops can help manage your symptoms.

If your conjunctivitis is a result of allergies, then using antihistamines may help relieve symptoms. Addressing the root cause is your best option for allergic conjunctivitis.

Some natural ways to potentially control allergy symptoms include:

• Stress management
• Apple cider vinegar
• Vitamin C
• Butterbur
• Bromelain
• Probiotics
• Quercetin

Irritants causing pink eye can be relieved with an eye flush and cold compress.

Conjunctivitis (Pink Eye) Prevention Tips

Viruses and bacteria lurk everywhere, and are very easily contracted. Touching an infected surface before touching your face can lead to infection, as can sharing towels, shaking hands, and other forms of contact. Taking this into account can greatly reduce your risk of contracting pink eye, COVID-19, colds, the flu, and other infections.

Consider the following tips:

• Wash your hands with soap and warm water when you return home from an outing. If this is not possible, use alcohol-based sanitizer (at least 60%).
• Wash your hands before and after cleaning your eyes and following any contact with treatments.
• Avoid touching and/or rubbing your eyes.
• Wash sheets, pillow cases, and towels in warm water. If you have an infection, wash these items regularly.
• Keep glasses and contact lenses clean and use as directed.
• Limit hand-to-hand contact with people.
• Don’t share personal items.
• Keep makeup brushes and other facial products clean; discard if you get pink eye.
• Only wash pink eye discharge when your hands are clean, using cotton balls. Discard cotton balls and wash your hands afterwards.
• Stay hydrated.
• Eat a nutritious diet rich in antioxidants.
• Keep your home clean.
• Limit exposure to allergens and irritants.

Final Thoughts on Conjunctivitis (Pink Eye)

Conjunctivitis (pink eye) is an infection or inflammation of the eye that has gained more attention during the coronavirus pandemic. However, pink eye can result from bacteria, allergens, and irritants of all types in addition to viruses.

Practicing good hand hygiene can help to reduce the spread of all viral and bacterial infections. Whether you’re trying to avoid COVID-19 or pink eye, the best way to limit your risk of infection is through maintaining good hygiene and identifying high-risk environments.

Avoiding contact with any potential allergens or irritants will reduce your chances of getting allergic or irritant conjunctivitis.