Written by Ada’s Medical Knowledge Team
What is bacterial conjunctivitis?
Conjunctivitis is the name for inflammation of the conjunctiva; this is the thin layer of tissue on the inside of the eyelids and covers the white part of the eye. Also known as pink eye, conjunctivitis is often caused by bacteria, a virus (see viral conjunctivitis) or allergies (see allergic conjunctivitis). If pink eye is caused by bacteria, it is called bacterial conjunctivitis. Like all types of pink eye, bacterial conjunctivitis is common but not usually serious. 1 2 3 4 5
- Pinkness or redness of the eye
- Burning, itching, a sensation of grittiness, or mild pain or discomfort in the eye
- Thick, sticky discharge from the eye
- Swollen and/or reddened eyelids
If you think that you might have pink eye, you can try using the Ada app to find out more about your symptoms.
Many cases of mild bacterial conjunctivitis clear up on their own, within a week or two and without any specific treatment. Cleaning the eyes throughout the day with water and a clean cloth or sterile pad, and using lubricating eye drops, also known as artificial tears, may help to relieve symptoms. However, antibiotic eye drops or ointments may be recommended, particularly for more severe cases of bacterial conjunctivitis. 1 2 3 4
Generally, people make a complete recovery, and the condition does not cause any complications. However, if bacterial conjunctivitis occurs in newborn babies or people with weakened immune systems, such as those who have HIV or are undergoing treatment for cancer, it can be very serious, and medical advice should be sought without delay. 1 6
- Intense pain in the eye
- Extreme redness in the eye
- Inability to open the eye
- Severe sensitivity to light
- Blurred vision that persists after wiping away discharge
Furthermore, if symptoms are mild but do not go away, medical advice should also be sought.
Bacterial conjunctivitis can affect people of any age, but it is more common in children than adults. 4 It is very contagious, which means that it can be spread easily from person to person. For this reason, it is important for people who have bacterial conjunctivitis to take steps to avoid passing it on to others, such as practicing good hygiene.
Symptoms of bacterial conjunctivitis
- Pinkness or redness in the eye
- Burning, itching, a sensation of grittiness, or mild pain or discomfort in the eye
- Increased watering of the eye
- Thick, sticky, often yellowish discharge from the eye; this can form a “crust” at night, making the eyes feel as if they are glued shut in the morning
- Swollen eyelids
- Slight sensitivity to bright light
- Swelling of the lymph nodes in front of the ears
Bacterial conjunctivitis usually only causes mild symptoms and does not affect a person’s vision, other than causing slight blurriness when discharge has built up on and around the eye. 4 7 Depending on the type of bacteria causing the infection, there may be additional symptoms. If you are worried that you may have pink eye, you can try using the Ada app to find out more about your symptoms.
If symptoms are severe or vision is impaired, it is important to contact a doctor without delay. It is also extremely important to see a doctor if any signs of bacterial conjunctivitis are present in a newborn baby.
Causes of bacterial conjunctivitis
The most common causes of bacterial conjunctivitis are the following types of bacteria: 7
- Staphylococcus aureus
- Staphylococcus epidermidis
- Streptococcus pneumonia
- Haemophilus influenzae; this is not the same as the flu, which is caused by a virus
Less commonly, the infection can be the result of the following sexually transmitted infections (STIs): 4
Bacterial conjunctivitis caused by chlamydia or gonorrhea is more serious and requires treatment by a doctor.
Diagnosis of bacterial conjunctivitis
When symptoms are mild, a diagnosis of bacterial conjunctivitis can often be made without seeing a doctor, and the condition can be treated at home. However, if there is any uncertainty or concern over the condition, or the symptoms are severe, seeing a doctor is very important.
A doctor will take the person’s medical history and ask whether anyone they know might have had an eye infection recently. They will examine the eyes and assess the signs and symptoms present, taking care to rule out acute viral conjunctivitis, allergic conjunctivitis and other more serious eye conditions, such as uveitis. 3 5 7
In most cases, it will not be necessary to order laboratory tests to confirm the diagnosis. However, in cases that are severe or do not respond to treatment, as well as in the case of infants, the doctor may take a small swab from the eyelid and test it to determine the cause of the infection and ensure that the treatment approach is correct. 8 9 5
Treatment for bacterial conjunctivitis
Mild cases of bacterial conjunctivitis often clear up within 1-2 weeks without special medical treatment.
- Gently cleaning discharge from the eye with a clean cloth, sterile pad or cotton wool soaked in water
- Applying lubricating eye drops, called artificial tears, which are available without a prescription, to the eye; care must be taken not to use the drops in the other eye, if only one eye is infected
- Applying a cold or warm compress, a clean cloth that has been soaked in water, to the eye
- Avoiding the use of contact lenses until the infection has cleared
Antibiotics for bacterial conjunctivitis
Antibiotic eye drops or eye ointment may help to clear up the infection more quickly. However, they are not always needed, and many cases of mild bacterial conjunctivitis will resolve on their own, without antibiotic treatment. 7
Complications of bacterial conjunctivitis
Most cases of mild bacterial conjunctivitis clear up completely, without causing any complications. However, in a small number of severe cases, the infection can cause serious complications, including: 7
- Ulcers on the cornea of the eye
- Damage to vision
- Otitis media, an ear infection
If a person experiences any severe symptoms, or is concerned about an eye infection, it is recommended that they see a doctor without delay.
Bacterial conjunctivitis in newborns
Infants can be affected by various types of conjunctivitis, including bacterial conjunctivitis. Pink eye in newborns is called neonatal conjunctivitis or ophthalmia neonatorum. Babies with bacterial conjunctivitis typically develop puffy, red eyelids and discharge from the eyes within 1-14 days of birth. 3
Conjunctivitis in babies is sometimes mistaken for sticky eyes caused by a blocked tear duct. However, a blocked tear duct will not cause redness or swelling. 4
Prevention of bacterial conjunctivitis
- Avoiding contact with people who have pink eye
- Maintaining good hygiene, such as washing your hands often with soap and water, or using hand sanitizer
- Avoiding touching your eyes when your hands are not clean
- Maintaining good hygiene, such as washing your hands often with soap and water, or using hand sanitizer, especially after treating the eyes
- Cleaning your spectacles
- Avoiding touching the eyes other than when treating them, as this can spread the bacteria
- Washing pillowcases and towels often and avoiding sharing them with others
- Avoiding sharing makeup and eye drops
- When necessary, staying off school or work until symptoms of bacterial conjunctivitis have cleared; this is generally when the eyes are no longer red and irritated
- Avoiding the use of swimming pools
In addition, contact lenses should not be worn until symptoms have cleared, and a new pair used when the infection has gone away. Some makeup may also need to be discarded and replaced to prevent reinfection. 10 1
Bacterial conjunctivitis FAQs
Q: Viral vs. bacterial conjunctivitis – what is the difference?
A: While both types of conjunctivitis are highly contagious, the causes, some of the symptoms and the treatments are different. Viral conjunctivitis is caused by a virus, often from the group of viruses that cause the common cold, results in a watery discharge from the eye, and has no specific treatment. Bacterial conjunctivitis is caused by bacteria, often types of staphylococcus or streptococcus, is spread through poor hygiene or contact with other people or insects, results in a thick, sticky discharge from the eye, and may – in some cases – require antibiotic eye drops. 8 9 2 11 If you think that you may have a type of pink eye, you can try using the Ada app to find out more about your symptoms.
Q: My child has bacterial conjunctivitis. Is it necessary to keep them home from school?
A: It depends on the region and institution. Some experts feel that a child should not be required to stay at home with bacterial conjunctivitis, unless an outbreak of multiple cases has occurred. However, a particular daycare center or school may have their own policy and ask that a child with bacterial conjunctivitis be kept at home until their symptoms have cleared up, to reduce the likelihood of infecting other children. 4
Other names for bacterial conjunctivitis
- Bacterial eye infection
- Pink eye, or pinkeye