Pink eye, or conjunctivitis, may present as one or both eyes looking red and becoming irritated. Other symptoms can include discharge, increased tearing, and crusting.

”Pink eye” is the nonclinical term for conjunctivitis. It is a type of eye inflammation that affects the conjunctiva, which is the thin, moist membrane covering the white of the eyes and the inner eyelids.

Conjunctivitis can be present in one eye or both. It is common and does not always require a visit to the doctor.

This article explores the types of conjunctivitis and how to recognize symptoms.

Irritation of the conjunctiva can happen for different reasons. Four primary types of conjunctivitis exist, which doctors classify by cause:

  • bacterial — transmissible
  • viral — transmissible
  • allergic
  • irritant

Certain symptoms may be more common in specific types of conjunctivitis, but general symptoms include:

Bacterial symptoms

Bacterial conjunctivitis often causes thick discharge, or pus, in and around the eye. It can cause the eyelids to stick together and may occur alongside an ear infection.

Although it is usually not painful, bacterial conjunctivitis can seem alarming due to excessive yellow-green discharge.

Viral symptoms

More watery discharge is associated with viral conjunctivitis. This typically starts in one eye, spreading to the second eye over a few days. It may coincide with a respiratory infection such as flu.

A person will also usually experience swollen lymph nodes in front of their ears.

Pain, light sensitivity, and redness are more prevalent in viral infections.

Allergic symptoms

When an allergy causes conjunctivitis, both eyes are usually affected. Itching, swelling, and excessive tearing are common symptoms. Discharge tends to remain clear.

Learn more about allergic conjunctivitis.

Irritant symptoms

Foreign bodies, eye trauma, and chemical exposure are all examples of irritants that can cause conjunctivitis.

Symptoms tend to be redness, swelling, and excessive tearing.

It is possible to have a stye and conjunctivitis at the same time, but they are separate conditions.

Conjunctivitis is irritation of the conjunctiva. It is often a type of infection, but not always. Conjunctiva irritation can also occur due to noninfectious agents, such as allergens and irritants.

Styes are pustules of infection that form in the glands of the eyelid. They only affect the eyelid they develop in, whereas conjunctivitis involves both lids and the white of the eye.

Learn more about styes.

With so many potential causes, there is no singular test for conjunctivitis. Doctors typically diagnose conjunctivitis by visually assessing a person’s symptoms. They also ask about a person’s eye health history and whether they have associated symptoms.

In addition to assessing outward signs, physical eye tests help doctors evaluate the structures and function of the eye.

Doctors may use fluorescein eye stain to identify herpes simplex virus (HSV) when conjunctivitis occurs alongside a history of cold sores or other skin lesions. This involves using a nontoxic greenish-orange dye and UV light to look for abnormalities on the usually smooth corneal surface.

In severe cases, or when conjunctivitis is chronic, conjunctival tissue scrapings may also be necessary.

Conjunctivitis treatment depends on the underlying cause, but most cases result from self-limiting viruses, which resolve on their own within 1–2 weeks.

Even though antibiotics are ineffective for viral conjunctivitis, symptom relief may still be possible using:

A doctor may prescribe topical steroid drops to reduce inflammation if symptoms are severe. If HSV causes conjunctivitis, a doctor may recommend antiviral therapy.

Antiviral medications include:

  • trifluridine 1% drops
  • ganciclovir 0.15% gel
  • oral acyclovir

Bacterial treatment

Doctors may prescribe antibiotic eye drops or ointments to treat bacterial conjunctivitis. A person must use them on the affected eye every 2–6 hours for up to 7 days. Antibiotics include:

Allergic treatment

Allergy avoidance is the primary treatment and prevention approach for allergic conjunctivitis. Other treatment approaches include topical medications such as:

Oral antihistamines and immune modulators may be necessary when allergic conjunctivitis is part of a more systemic reaction.

Cold compresses may be more soothing than warm compresses for allergic conjunctivitis.

Read more about infective conjunctivitis, including prevention.

Most conjunctivitis cases are easy to treat, self-limiting, and leave no lasting damage to the eye.

The Centers for Disease Control and Prevention state that people with conjunctivitis symptoms may wish to avoid close contact with others to avoid transmitting the infection.

Conjunctivitis is irritation to the eye’s conjunctiva. It is typically self-limiting and resolves within 2–3 weeks.

The main symptoms include redness, itching, burning, discharge, and eye crusting. Causes include bacterial or viral infection or an allergic reaction to an allergen, such as pollen or mold spores.

Doctors may recommend eye drops to treat conjunctivitis and home remedies such as a cold or warm compress.