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Conjunctivitis, also commonly known as pink eye, is the inflammation of the outermost covering of our eye called the conjunctiva. It is a common condition and can occur at any age due to allergies, infections, or environmental factors. Conjunctiva is the protective layer of our eyes. When an external factor or infective agent triggers this layer, it leads to the inflammation of the conjunctiva, which results in the characteristic ‘pink eye’ appearance. It usually lasts for a short time and can be resolved with or without treatment.


There are multiple causes of conjunctivitis. It can occur due to viral or bacterial infection, allergic reaction, irritable contact lenses, chemical irritation, etc. Viral infections cause the majority of cases of infective conjunctivitis. Common viruses that lead to inflammation of conjunctiva include adenovirus, herpes simplex virus, rubella virus, Epstein-Barr virus, varicella-zoster virus, etc. Common causative agents of bacterial conjunctivitis include streptococcus pneumoniae, staphylococcus aureus, Haemophilus influenzae, Neisseria gonorrhoeae, etc. Certain viruses can result in severe septic conjunctivitis that occurs in newborn babies. Allergic conjunctivitis is much more common than infectious conjunctivitis. Causes of allergic conjunctivitis include airborne irritants, pollen, smoke, dust particles, toxic fumes, eye drops, etc. Other conditions that may lead to conjunctivitis include Sjogren’s syndrome, trauma or injury to the eye, reduced mucin production, or nutritional deficiencies.


Conjunctivitis can be divided into three types based on the onset and duration. These include hyperacute, acute, and chronic conjunctivitis.

Hyperacute conjunctivitis is the most severe form of conjunctivitis, usually caused by a bacterial infection. The involved bacteria are Neisseria gonorrhoeae and Neisseria meningitides. Both eyes are affected in most cases, accompanied by a greenish-yellow discharge. It has an abrupt onset and needs immediate care and management.

Acute conjunctivitis is the most common form, and it is caused by viral or bacterial infections, allergies, or chemical irritants. The symptoms are mild compared to hyperacute conjunctivitis. It does not require a specialist’s care, and most cases resolve by themselves within a few days.

Chronic conjunctivitis is usually caused by bacterial infections as well. The bacteria, in this case, can be antibiotic-resistant and can persist for longer than six days. This causes extreme irritability in the affected individuals and disrupts their normal daily activities. 

Risk Factors And Epidemiology

Various risk factors are involved in the development of conjunctivitis. A major risk factor for infective conjunctivitis is coming in contact with the eye discharge of an infected person. Sharing contact lenses or other personal items, ill-maintained hygiene, and weak immunity can also make you prone to infective conjunctivitis. Risk factors associated with allergic conjunctivitis include pollen, dirt particles, toxic perfumes, chemical irritants, smog, smoke, etc. Drying eyes due to medication or diseases is also a risk factor for conjunctivitis. Newborn babies are at risk of contracting conjunctivitis from their infected mothers during vaginal delivery. 
Conjunctivitis may affect individuals of any age. However, studies have reported that viral conjunctivitis is more prevalent among adults and bacterial conjunctivitis is more prevalent among children. During delivery, neonatal conjunctivitis is also commonly spread by infected mothers to their babies. Conjunctivitis occurs in both males and females equally.

Signs And Symptoms

Signs and symptoms of conjunctivitis depend on its cause. Redness, irritation, and watery eyes are common symptoms of every type. Viral conjunctivitis is generally accompanied by other symptoms, including fever, headache, sore throat, runny nose, etc. It is the type with the least pain or irritation. Bacterial conjunctivitis can have mild to severe symptoms, including pain, itching, swelling of eyelids, and pus discharge from the affected eye or eyes. Neonatal bacterial conjunctivitis develops hyperacute symptoms that may risk the newborn baby’s vision. Allergic conjunctivitis causes constant watery eyes, irritation, and itching in both eyes. Other symptoms experienced during conjunctivitis may include foggy or blurry vision, sensitivity to light, mucoid discharge, constant blinking, swelling of eyelids, or subconjunctival hemorrhage.


The first step towards diagnosing conjunctivitis is to obtain a detailed history and a thorough clinical examination. History of symptoms, onset, duration, and allergies can point towards the pathological cause. Clinical examination of the eyes and other systemic signs and symptoms also aids in diagnosis. Ophthalmologic examination is done in patients with severe symptoms of conjunctivitis. In certain cases, your eye doctor may recommend suitable diagnostic tests for infection, allergies, or other diseases if they are suspected of identifying the primary cause.

Differential Diagnosis

It is necessary to differentiate conjunctivitis from other conditions with similar symptoms. These include scleritis, glaucoma, keratitis, blepharitis, dry eye syndrome, iritis, nasolacrimal duct obstruction, orbital cellulitis, uveitis, etc.


Treatment of conjunctivitis is based upon its cause. Viral conjunctivitis does not require treatment in most cases and usually recovers well on its own with only symptomatic care. Mild cases of bacterial conjunctivitis need supportive care, but antibiotic eye drops or topical ointments treat severe cases. Allergic conjunctivitis requires washing your eyes with cold water, artificial tear drops, and antihistamines to reduce symptoms. Corticosteroids may also be indicated in some cases. Analgesics are prescribed if the pain is persistent.


Antibiotics such as chloramphenicol, fluoroquinolones, sodium sulfacetamide, etc., are prescribed only in cases of severe conjunctivitis with pus discharge. Antihistamines such as diphenhydramine, loratadine, etc., are prescribed in cases of allergic conjunctivitis. Analgesics such as naproxen, ibuprofen, etc., are preferred if there is severe pain and inflammation. 


The majority of the cases of conjunctivitis recover well within three days to a week. If the severe bacterial infection persists, immediate medical attention is required to prevent complications.


Prevention methods for conjunctivitis include maintenance of hygiene, avoiding direct contact with the infected discharge of other patients, washing hands frequently, using a hand sanitizer, avoiding rubbing eyes, avoiding sharing of contact lenses or other personal items (contact lens solution, makeup brushes, etc.), avoiding active and passive smoking and changing your bedcovers/pillowcases frequently. Understanding the risk factors of conjunctivitis is critical to preventing this disease.


Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on April 29th, 2023.




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