Medically reviewed
Conjunctivitis (pink eye) is an infection in the thin outer membrane, called the conjunctiva, that covers a person’s eyeball. The infection causes the blood cells in the membrane to become inflamed and more visible, which in turn leads to the eye taking on a reddish or pinkish hue.
There are three major types of pink eye: allergic conjunctivitis, bacterial conjunctivitis, and viral conjunctivitis. Newborns and infants can develop conjunctivitis symptoms if they have underdeveloped tear ducts, while children and adults can develop pink eye if their eyes have recently been exposed to certain irritants (like pool chlorine), too.
Though it rarely affects vision or other functions of the eye, conjunctivitis can be uncomfortable, unsightly, and, if it’s viral or bacterial, highly contagious. So how do you get pink eye? How long does pink eye last? And how long is pink eye contagious?
What Is Conjunctivitis?
Conjunctivitis is an infection in the conjunctiva, the outer membrane of your eye that covers the whites of your eyeball and lines the inside of your eyelids. When your conjunctiva becomes irritated, the blood vessels within it become large and inflamed. Because they are larger than normal, the blood vessels are also more visible, which leads to the whites of the eyes taking on a pinkish or reddish color until the condition is cleared up.
Conjunctivitis is very common, affecting 6 million people in the United States every year. People can develop conjunctivitis because of seasonal allergies, exposure to irritants like smoke or chemicals like pool chlorine, or because of a bacterial or viral infection. Children often develop pink eye because the bacteria and viruses that can cause the condition are highly contagious and can easily spread between children in daycares and school settings.
Although pink eye is uncomfortable and unsightly, it is rarely dangerous. Conjunctivitis will rarely impact a patient’s vision or cause other lasting damage, particularly if the condition is treated quickly.
Types of Conjunctivitis
Most patients develop conjunctivitis because they have been exposed to an allergy, virus, or bacteria that causes a reaction in their eye.
Allergic conjunctivitis is a common condition that often affects people with seasonal allergies. When certain people are exposed to environmental allergens, it can trigger a misplaced immune response that includes eye redness and irritation, as well as coughing, sneezing, and other symptoms.
There are two types of allergic conjunctivitis:
- Acute allergic conjunctivitis: Often appearing during hay fever season, acute allergic conjunctivitis is short-term but uncomfortable. Conjunctiva redness is often accompanied by itchy or burning eyes, and a runny nose.
- Chronic allergic conjunctivitis: Although it is less common, some people develop chronic allergic conjunctivitis in response to pet dander, certain foods, or dust. Symptoms tend to be mild but include burning eyes, itching eyes, and light sensitivity in addition to eye redness.
Some people may develop allergic conjunctivitis in response to certain perfumes, chemicals, medications, or certain contact lens solutions.
Bacterial conjunctivitis is often caused by bacteria like Staphylococcus aureus and Streptococcus pneumoniae, the same germs that cause strep throat and staph infections. It can develop when a patient has a cold or flu, when they haven’t cleaned their contact lenses properly, or when they have shared contact lenses with someone else. Bacterial conjunctivitis usually affects only one eye, though it can sometimes spread to both. Patients usually develop a lot of mucus in the infected eye, along with eye redness and irritation.
Viral conjunctivitis is a very common form of pink eye. Most cases are caused by adenoviruses, the same family of viruses that are behind many common colds. It can also be triggered by an infection from the varicella-zoster virus, herpes simplex virus, and the virus that causes the novel coronavirus (COVID-19). A viral conjunctivitis infection often begins in one eye and then infects the other, causing redness, irritation, and watery discharge.
Is pink eye contagious?
If your pink eye is caused by an allergy or chemical irritant, it is not contagious, but both bacterial and viral conjunctivitis spread quickly and easily. If you suspect you have a bacterial or viral infection, take precautionary measures to keep from spreading it to other people. Refrain from touching or rubbing your eyes, wash your hands often, avoid sharing personal eye care products with others, and change your towels and pillowcases regularly.
Pink Eye Symptoms
In addition to a pink or reddish tint to their eye, patients with conjunctivitis can experience a range of symptoms related to the condition, depending on the kind they have.
The most common symptoms include:
- Redness or irritation
- Itchiness
- A burning sensation
- A sandy or gritty feeling in one or both eyes
- Tearing or watery eyes
- Mucus or pus in one or both eyes that forms a crust during the night
- A watery or runny nose
If you have viral or bacterial conjunctivitis, you may also experience:
However, there are other conditions that cause eye redness that aren’t pink eye. These conditions require immediate treatment. If you feel significant eye pain or discharge, feel like something is in your eye, have vision problems, or are sensitive to light, call your doctor to discuss your symptoms further.
If you have a newborn that is suffering from pink eye in the first thirty days of life, call your pediatrician. Your baby may be suffering from a condition called Ophthalmia Neonatorum, a rare but serious form of conjunctivitis that requires immediate treatment.
What Causes Pink Eye?
Pink eye can be caused by chemical or environmental irritants, bacterial or viral infections, or, in the case of some newborns, underdeveloped tear ducts. Very rarely, conjunctivitis can be caused by certain fungal and amoebic parasites.
Common environmental causes of allergic conjunctivitis include:
- Mold spores
- Tree or flower pollen
- Pet dander
- Certain foods
- Smoke
- Dust
- Ingredients in cosmetics
- Pool chlorine
- Contact lenses
- Certain shampoos and conditioners
- Dirt
- Medications
- Eye drops
Bacterial and viral conjunctivitis infections are caused by the same germs that cause the common cold, the flu, certain sexually-transmitted diseases, strep throat, staph infections, and COVID-19, among others.
Diagnosing Pink Eye
Your doctor may start an assessment over the phone, asking about your symptoms, recent activities, health history, and allergies. They may ask you whether you are experiencing itchiness or irritation, have any watery or thick discharge, or whether you are experiencing any other cold, flu, or allergy symptoms. If a doctor’s visit is needed, they may examine your eyes and check your vision.
Pink Eye Treatment
Each kind of pink eye requires a different kind of conjunctivitis treatment. If your pink eye is caused by an allergy, your doctor may suggest medicated pink eye drops that contain antihistamines, or prescribe medications that can help control inflammatory allergic responses like decongestants or steroids.
If a bacteria is causing your conjunctivitis, your doctor may prescribe antibiotic eye drops or eye ointment to help you fight off the infection. You should see significant improvement after only a few days of conjunctivitis treatment.
If you have viral conjunctivitis, there are unfortunately no medicated pink eye treatment options that will alleviate your symptoms while your infection is running its course. Though it will take 7-10 days for your infection to clear completely, there are home remedies for pink eye that you can use in the meantime to soothe your irritation. They include:
- Placing a warm or cool compress on one or both eyes
- Placing a wet cloth on one or both eyes
- Taking an over-the-counter medication like ibuprofen (Advil) or acetaminophen (Tylenol)
- Using over-the-counter false tears or eye drops to help lubricate your eye
- Stop wearing contact lenses for the duration of your infection
If your pink eye is caused by a chemical irritant, first treat it by rinsing your eyes in a lot of cold, clear water. If your symptoms do not clear up right away, or if you have been splashed by a caustic chemical, go to the ER for evaluation. A foreign object or chemical splash in your eye can cause lasting damage if it is not treated correctly.
How to Prevent Conjunctivitis
The best way to prevent contracting conjunctivitis is to always practice good hygiene. Some precautions you can take include:
- Refraining from touching your eyes with your hands
- Washing your hands often, with soap and warm water
- Using a clean towel daily
- Changing your sheets and pillowcases often
- Changing your cosmetics, particularly mascara, every three months
- Cleaning your contact lenses regularly
- Never sharing towels, washcloths, eye cosmetics or contact lenses.
- Staying away from exposure to environmental allergens or chemical irritants that negatively affect your eyes
If your doctor believes that you are developing pink eye because of your personal eye care items like contact lenses or contact lens solutions, you may be asked to avoid wearing contact lenses or consider switching to an alternative brand.
Risk Factors and Complications
Conjunctivitis is very common, but certain factors make individuals more at risk for developing the infection than others. They include:
- Being exposed to an allergen
- Being exposed to a chemical or environmental irritant
- Sharing personal eye care items
- Interacting with someone with pink eye
- Wearing contact lenses
Most cases of conjunctivitis are mild and clear up with medication, home treatments, or on their own. In very rare, severe cases, bacterial or viral conjunctivitis can spread to other parts of the body and cause secondary infections. Severe conjunctivitis can also lead to corneal inflammation in both children and adults that can affect patient vision. If you believe that you have something in your eye, develop a sensitivity to light, have blurred vision or other eye concerns, call your doctor right away.
When to See a Doctor
Although conjunctivitis is common, it’s important to treat it quickly. If your symptoms persist more than 12-24 hours, you have developed conjunctivitis in response to a chemical splash, you are suffering from other cold and flu symptoms, or you are experiencing blurred vision, sensitivity to light, eye pain, or feel that something is stuck in your eye, call your doctor right away. You could be suffering from a conjunctivitis infection or another eye condition that requires further treatment.
If you have a newborn that is suffering from pink eye in the first thirty days of life, call your doctor. Your baby may be suffering from a condition called Ophthalmia Neonatorum that can affect their long-term vision and requires immediate treatment.
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