What is infective conjunctivitis, or pink eye?

What is infective conjunctivitis, or pink eye?

Conjunctivitis, or “pink eye,” occurs when the eye’s conjunctiva gets inflamed. The eye may become red or pink, swollen and irritated and mucus may be present. Conjunctivitis can be highly infectious.

The conjunctiva is a thin cell layer, or membrane, between the eyelids’ inner surface and the eye whites.

Inflammation causes tiny blood vessels, or capillaries, in the conjunctiva to become more prominent. This causes discomfort and the appearance of pink or red, which can last from a few days to several weeks.

Causes include pain , infection, and allergy. This article will concentrate primarily on infectious conjunctivitis.

Important facts about conjunctivitis:

Here are some of the main points about conjunctivitis, or pink eye. More details are given in the main article.

  • Pink eye can result from an allergy, an irriation, or an infection.
  • A virus or a bacteria can cause an infection. Sometimes it is linked to a sexually transmitted infection (STI).
  • Antibiotics are sometimes used, but they will not help if the cause is a virus.
  • Symptoms normally last up to 2 weeks, but they can persist for longer.
  • It is important to wash hands carefully and not to share personal items, such as towels, as this can spread the infection.


Eyes Bacteria
Inflammation can result from different kinds of bacteria or viruses.

Signs and symptoms may include the following:

  • redness, because of irritation and widening of the tiny blood vessels in the conjunctiva
  • a shiny, watery eye, as the tear glands become overactive
  • a sticky or crusty coating on the eyelashes, especially on waking after a long sleep, because the infection produces mucus
  • soreness and “grittiness,” like sand in the eye
  • swelling, due to inflammation or rubbing

The redness and soreness may affect one eye first, then spread to the other.

Other symptoms

There may also be:

Swollen lymph nodes: The lymph node in front of the ear becomes slightly tender and swollen. It can feel like a button under the skin. The lymph node is a part of the immune system in the body that fights infection.

Respiratory tract infection: The person may have flu-like symptoms such as fever , headache, painful limbs and sore throat.

A person should see a doctor if:

  • the eye is very red and painful
  • vision is affected
  • the eye becomes very sensitive to light

These symptoms may indicate a more serious condition.

Newborns sometimes grow pink eyes. Symptoms include eyelids which are red, tender and puffy. Urgent medical attention is needed to prevent complications and to identify and treat any conditions that underlie them.


Nearly half of infectious conjunctivitis cases resolve within 2 weeks without any medical attention, and a doctor can recommend that you watch and wait.

They may prescribe eye drops with decongestants or antihistamines to lower swelling and irritation symptoms.

Antibiotics for infective conjunctivitis

Antibiotics will not help if the cause is viral, and even a bacterial infection may last up to a month with antibiotics. Some studies show that for 1 in 10 patients, antibiotics may help speed up recovery.

Treatment may include eyedrops containing antibiotics or an antihistamine.
Treatment may include eyedrops containing antibiotics or an antihistamine.

Antibiotics may however be prescribed if symptoms are severe or lasted longer than 2 weeks. A doctor may give drops in the eye to antibiotics just in case they help.

For infective conjunctivitis the most commonly prescribed antibiotics are:

  • fluoroquinolones
  • tetracyclines
  • sulfonamides
  • chloramphenicol

These are eye drops or ointment which are administered directly to the eye. Dosage depends on the type. Ointments can be better to use on an infant or young child than eye drops.

Vision can become blurry shortly after using eye drops. When driving or running machinery make sure that you see clearly. If there is no improvement in the symptoms, or pain or blurry vision, you should go back to the doctor.

Self care

A number of home remedies can help ease the symptoms and may accelerate recovery.

Contact lenses: Do not use lenses until at least 24 hours after completion of antibiotic treatment, then throw away and replace lenses, lens case and solution

You can buy artificial tear-eye drops over the counter ( OTC) to help relieve soreness and stickiness.

Several times a day a wash cloth soaked in warm water can be used to clean any sticky substances gently. Do this gently, so as to avoid eye irritation. For any eye using a clean washcloth.

Regular washing of hands with warm water and soap will help prevent infection from spreading.

Warm compresses can soothe discomfort. Soak a clean, lint-free cloth in warm water, wring it out, and gently add to the eye that is closed.

The symptoms below may indicate a more serious condition. They need immediate medical assistance:

  • pain in the eye
  • sensitivity to light, or photophobia
  • loss of vision
  • very intense redness

Usually the condition becomes no longer contagious when the eyes look and feel normal again.


Eye infection can be caused by a virus or by bacteria.

Viruses causing conjunctivitis include adenoviruses, and some herpes virus types.

Bacterial causes include Staphylococcus aureus, Streptococcus pneumoniae, the species Haemophilus and Chlamydia trachomatis, which are less common.

Sometimes, bacterial conjunctivitis is due to a sexually transmitted infection ( STI), such as chlamydia. If after a month, symptoms do not disappear, this may indicate a STI. With treatment most other types of bacterial conjunctivitis will resolve faster.

Infective conjunctivitis is highly contagious and can be easily transmitted to another person.

Causes in newborns

In newborns, pink eye can be caused by infection, irritation or a blocked tear duct. The cause can be difficult to determine, because similar symptoms occur in each type.

The mother often passes on bacteria or a virus during childbirth, even though she has no symptoms. An STI can be linked to the bacteria or virus.

If a newborn has Chlamydia-related bacterial conjunctivitis, symptoms usually appear 5 to 12 days after delivery. If gonorrhea activates the bacteria, they normally turn up after 2 to 4 days.

It can also transmit the virus that causes oral and genital herpes at birth and appear as conjunctivitis.

Pink eye occurs in some cases as a reaction eyedrops given at birth, to prevent infection. The symptoms in this case usually pass after 24 to 36 hours.

Other causes of red eyes

Reddened eyes can also be a symptom of:

Blepharitis: This is an eyelid infection usually causing redness, pain and itching. The eyelashes will also feature dandruff-like scales. Blepharitis is not infectious.

Acute glaucoma: This is a rare type of glaucoma that causes pressure in the eye. Symptoms can quickly appear and include pain, red eyes and loss of vision, which can become permanent without treatment.

Keratitis: The cornea gets inflamed and maybe ulcerated. If scarring of the cornea occurs, this can lead to permanent loss of vision. At the front of the eye the cornea is the transparent part.

Iritis: The iris becomes inflamed. Untreated iritis can cause the iris to stuck onto the lens’ front surface, preventing the pupil from draining fluid. This can end up causing permanent damage to the eye. The iris is the colored part of the eye, that part which controls the amount of light entering the eye.


Depending on the cause there are three different types of conjunctivitis.

Chemical or irritating conjunctivitis: This can become inflamed and sore if something irritates the eye. The irritant could be an eyelash misdirected into the eye, or chlorine following a swim in a pool.

Allergic conjunctivitis: This occurs when an allergens, such as dust mites, pollen or animal fur, come into contact with the eye. An allergen induces an overreaction in the body’s immune system, causing pain and inflammation.

Infective conjunctivitis: An infection is caused by a bacteria or virus which makes the eyes red or pink and watery. The eyelashes and mucus can have sticky coating in the eyes.


A physician can diagnose conjunctivitis by examining the signs and symptoms and asking questions. Irritant and allergic conjunctivitis treatment for an infection is different from that.

Some infectious conjunctivitis cases resolve without treatment within a few days to 2 weeks but others can take up to a month. Antibiotics can shorten recovery time for bacterial conjunctivitis, and reduce the spread of infection to others.

If symptoms continue for 2 weeks or longer, the person will return to see their physician, who will reassess the condition and change the treatment.


For testing in a laboratory, the doctor may take a swab from the infected eye. Knowing what sort of bacteria causes the infection would help them to administer a suitable treatment. Most doctors, however, do not do that test.


The risk of catching or transmitting infectious conjunctivitis may be reduced with:

  • not touching or rubbing the eyes
  • washing the hands frequently with soap and warm water, or use hand sanitizer
  • always removing contact lenses at night, and following instructions about lens hygiene
  • keeping eyeglasses clean
  • not sharing personal items such as towels and pillows, make up and contact lenses with other people
  • using goggles in a swimming pool, and not swimming if you have an infection

It is a safe idea to throw out any contact lens solution and eye make up after the infection has gone away.

Avoiding potential or known irritants and allergens can reduce the risk of irritant and allergic conjunctivitis.

This includes ensuring that the rooms are well ventilated, cleaning and maintaining the air conditioning units, and avoiding smoky atmospheres.


The risk of bacteria or a virus causing complications caused by infective conjunctivitis is small. However, complications are likely when the pink eye is a symptom of an underlying disorder, such as a STI.

Newborns present an increased risk of complications. Infective neonatal conjunctivitis can be severe and can progress rapidly. It can impact vision in very severe cases.

Without treatment, 10 to 20 percent of newborns with Chlamydia-related infectious conjunctivitis will develop pneumonia, which may be life-threatening.

Other types of bacterial conjunctivitis can, in rare cases, also cause complications to a newborn.

These include:

  • Meningitis: A potentially fatal illness in which the meninges, a layer of cells that covers the brain and spinal cord, becomes infected.
  • Cellulitis: A bacterial infection of the deepers layers of skin and the fat and soft tissues that are under the skin.
  • Septicemia, or blood poisoning: Bacteria enter the bloodstream and attack the tissues in the body.

Most infants do, however, recover fully from infectious conjunctivitis without any complications.However, most infants make a full recovery from infective conjunctivitis with no complications.