Conjunctivitis, commonly known as pink eye or red eye, is inflammation of the conjunctiva, the thin, transparent membrane that lines the white of the eye and the inside of the eyelids. When this membrane becomes inflamed, its small blood vessels become more visible, giving the eye its characteristic pink or red appearance. Conjunctivitis is extremely common and, in most cases, mild: the majority of people recover fully, often without any lasting effect on vision.
However, conjunctivitis is not a single illness, it has several different causes (viral, bacterial, allergic, and irritant), and because the right treatment depends entirely on the cause, it is worth understanding which type you may have. Most cases are harmless, but a few symptoms are warning signs that need prompt eye care, and these are flagged clearly below.
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The conjunctiva is a clear membrane that covers the sclera (the white of the eye) and lines the inner surface of the eyelids. It helps keep the eye moist and protected. Conjunctivitis simply means this membrane is inflamed, from an infection, an allergy, or an irritant. Because the conjunctiva is rich in tiny blood vessels, inflammation makes these vessels dilate and become visible, which is why the eye looks pink or red. Conjunctivitis can affect one or both eyes, and whether it is contagious depends on the cause: infective types (viral and bacterial) can spread easily from person to person, while allergic and irritant conjunctivitis cannot be passed on at all.
Conjunctivitis can also be described by how long it lasts. Acute conjunctivitis lasts less than four weeks and is by far the most common form. Chronic conjunctivitis lasts longer than four weeks and is worth investigating, as persistent inflammation can point to an ongoing allergy, an irritant that has not been removed, or another underlying cause that needs addressing.
Identifying the type of conjunctivitis is the most important step, because the treatment, and whether it is contagious, differs completely between them. There are four main types:
While the common-cold viruses (the adenovirus family) are the usual cause, viral conjunctivitis can also occur with other viral illnesses, including measles, mumps, COVID-19, eye herpes (herpes simplex), molluscum contagiosum, and hand, foot and mouth disease. The eye herpes type is important to identify, because it needs specific antiviral treatment and should not be treated with steroid drops.
Less commonly, bacterial conjunctivitis can be caused by sexually transmitted infections such as chlamydia and gonorrhoea. This is particularly important in newborns (who can be affected during birth) and in adults with persistent conjunctivitis alongside genital symptoms, both situations need prompt, specific medical treatment rather than ordinary pink-eye care.
Less common causes
Rarely, a fungus or parasite can cause conjunctivitis, this is uncommon but can occur, for example, in contact lens wearers exposed to contaminated water. In addition, some non-eye conditions can cause redness that is mistaken for pink eye: autoimmune diseases, and in rare cases tumours or eye cancers, can all produce a persistently red eye. This is one more reason that a red eye which does not settle, or keeps coming back, deserves a proper eye examination rather than being assumed to be simple conjunctivitis.
While only an examination can confirm the cause, the pattern of symptoms often gives a strong clue:
These are guides, not a diagnosis, the types can overlap and look similar, which is why an eye specialist’s assessment is the reliable way to know, especially if symptoms are severe or not improving.
Symptoms vary by type, but common features include:
Importantly, ordinary conjunctivitis usually does not cause significant pain or loss of vision. Mild blurring that clears when you blink (from discharge) can happen, but genuine eye pain or reduced vision is a warning sign, not a normal part of conjunctivitis.
Most conjunctivitis is mild and settles, but the following symptoms suggest something more serious than simple conjunctivitis, such as an infection or inflammation deeper in the eye, and need prompt assessment by an eye specialist:
The causes map to the four types, and certain factors make conjunctivitis more likely:
Infective causes (viral and bacterial)
Allergic causes
Irritant causes
General risk factors
Treatment depends entirely on the type of conjunctivitis, which is why an accurate diagnosis matters. The aim is to relieve symptoms, treat the underlying cause where treatment is needed, and prevent spread. Any medication should be used as advised by an eye specialist.
Viral conjunctivitis
Most viral conjunctivitis clears on its own within one to two weeks, so treatment focuses on comfort and preventing spread rather than medication, cool compresses, lubricating eye drops (artificial tears) to ease irritation, and strict hygiene. Antibiotics do not work against viruses and are not helpful for viral conjunctivitis. Your specialist will advise if anything more is needed.
Bacterial conjunctivitis
Mild cases may settle without medication, but bacterial conjunctivitis is often treated with antibiotic eye drops or ointment, prescribed by an eye specialist, which can speed recovery and reduce spread. Gently cleaning away discharge with clean water and keeping up good hygiene also help.
Allergic conjunctivitis
The key is avoiding the trigger where possible. Treatment may include anti-allergy (antihistamine) eye drops, lubricating drops to wash out allergens, and cool compresses to ease itching. For ongoing or seasonal allergy, your specialist may recommend a longer-term approach. Because it is not an infection, it is not treated with antibiotics.
Irritant conjunctivitis
This usually improves once the irritant is removed and the eye is rinsed with clean water. Lubricating drops can soothe the surface. As noted, a chemical splash is an emergency and needs immediate rinsing and urgent care.
General comfort measures
Not sure which type you have, or symptoms not settling? The right treatment starts with the right diagnosis. Book a consultation.
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For most people, conjunctivitis is short-lived and resolves fully. Viral conjunctivitis usually clears within one to two weeks, though it can occasionally take a little longer, and symptoms sometimes seem to worsen in the first few days before improving. Bacterial conjunctivitis often improves within a few days, faster with treatment where it is needed. Allergic conjunctivitis improves once the trigger is removed or controlled, but can return with repeated exposure. Importantly, simple conjunctivitis typically heals without affecting vision. Your specialist will advise on the likely course for your specific case and when to follow up.
The outlook for conjunctivitis is generally very good. The great majority of cases are mild and resolve completely, with no lasting effect on the eye or vision. The main value of a proper diagnosis is twofold: making sure the right type is treated the right way, and, crucially, making sure a more serious condition is not being mistaken for ordinary pink eye. With the red-flag symptoms assessed and the cause correctly identified, conjunctivitis is a very manageable condition.
Viral and bacterial conjunctivitis are contagious, so good hygiene protects both you and the people around you. If you or a family member has infective conjunctivitis:
Many mild cases are recognised from the symptoms alone, but an eye specialist’s assessment is valuable when symptoms are significant, persistent, recurrent, or unclear, because it confirms the type and rules out more serious conditions. At Krishna Netralaya, assessment may include:
See an eye specialist if you have:
While much conjunctivitis settles on its own, an accurate diagnosis makes sure the right type is treated correctly and that nothing more serious is missed. If you are unsure or your symptoms are significant, book a consultation at Krishna Netralaya.
Disclaimer: All information, provided above is for informational purposes only and is not intended to serve as a substitute for the consultation, diagnosis, and/or medical treatment of a qualified physician or healthcare provider. Read our full disclaimer here.
Most conjunctivitis is mild and clears without any lasting effect on vision. It becomes a concern only if there are red-flag symptoms, such as eye pain, reduced vision, or strong light sensitivity, or if it occurs in a contact lens wearer or a newborn, which need prompt eye care.
It depends on the cause. Viral and bacterial conjunctivitis are contagious and spread easily through contact and shared items. Allergic and irritant conjunctivitis are not contagious and cannot be passed to others.
Viral conjunctivitis usually clears within one to two weeks. Bacterial conjunctivitis often improves within a few days, especially with treatment where it is needed. Allergic conjunctivitis lasts as long as you are exposed to the trigger.
The pattern helps: watery discharge after a cold suggests viral; thick yellow-green discharge with stuck-together lids suggests bacterial; intense itching in both eyes with sneezing suggests allergic. These are clues only, an eye specialist's examination gives the reliable answer, especially if symptoms are severe or persistent.
Not always. Antibiotics only help bacterial conjunctivitis, and even then mild cases may settle on their own. They do not work for viral or allergic conjunctivitis. Using the wrong treatment is one reason it is worth getting the type diagnosed.
No. Stop wearing lenses until the eye has fully recovered and a specialist confirms it is safe. Wearing lenses with conjunctivitis can worsen it and, importantly, raises the risk of a more serious corneal infection. Discard disposable lenses worn just before symptoms began.
Simple conjunctivitis usually does not affect vision. You may get mild blurring from discharge that clears when you blink. Genuine reduced vision is not a normal part of conjunctivitis and should be checked promptly.
Wash hands often, avoid touching the eyes, do not share towels, pillows, or cosmetics, wash bedding and cloths frequently, and avoid contact lenses while infected. These steps greatly reduce the chance of passing on viral or bacterial conjunctivitis.
