Viral or Bacterial Conjunctivitis

What Is Conjunctivitis (Pink Eye)?

Conjunctivitis — commonly called pink eye — is inflammation of the conjunctiva, the thin clear membrane that lines the inner eyelids and covers the white of the eye. When this membrane becomes infected or irritated, the blood vessels dilate and produce the characteristic red or pink appearance.

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Viral and bacterial conjunctivitis are the two infectious forms of the condition. Both are highly contagious and can spread rapidly through households, schools, and workplaces. At West Boca Eye Center in Boca Raton, the team provides prompt diagnosis to determine the type of conjunctivitis and initiate the correct treatment — an important distinction because viral and bacterial forms require different management approaches.

Viral Conjunctivitis

Viral conjunctivitis is the most common form of infectious pink eye. It is caused by the same family of viruses (adenoviruses) responsible for the common cold and upper respiratory infections.

How It Spreads

Viral conjunctivitis is highly contagious and can spread through:

• Direct contact with tears, nasal discharge, or respiratory droplets from an infected person
• Touching your eyes after contact with contaminated surfaces (doorknobs, countertops, shared devices)
• Sharing towels, pillowcases, washcloths, or eye makeup
• Coughing or sneezing near others

The contagious period typically lasts 10 to 14 days from the onset of symptoms, even as the condition begins to improve.

Symptoms of Viral Conjunctivitis

• Watery, clear discharge (not thick or pus-like)
• Redness in one or both eyes — often starts in one eye and spreads to the other within days
• Itching or a gritty, sandy sensation
• Sensitivity to light (photophobia)
• Swollen eyelids
• Enlarged, tender lymph nodes in front of the ear (preauricular lymphadenopathy)
• Often accompanies or follows a cold, sore throat, or upper respiratory infection

How Viral Conjunctivitis Is Treated

Because viral conjunctivitis is caused by a virus, antibiotics are not effective. The infection typically resolves on its own within two to four weeks. Supportive care includes:

• Cool compresses — applied to closed eyelids several times a day to reduce swelling and discomfort
• Preservative-free artificial tears — to soothe irritation and wash away discharge
• Antihistamine or anti-inflammatory eye drops — to reduce itching and redness during the recovery period
• Strict hygiene measures — frequent handwashing, avoiding eye touching, and not sharing personal items to prevent spread

In severe cases — particularly those involving the cornea (epidemic keratoconjunctivitis) — your ophthalmologist may prescribe topical corticosteroids under close monitoring to prevent corneal scarring.

Bacterial Conjunctivitis

Bacterial conjunctivitis occurs when bacteria colonize the conjunctival surface. The most common culprits include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. In newborns, Neisseria gonorrhoeae and Chlamydia trachomatis are serious causes that require urgent treatment.

How It Spreads

Bacterial conjunctivitis spreads through the same contact routes as viral forms — contaminated hands, shared personal items, and direct contact with infected discharge. It can also develop secondary to other infections such as sinusitis or otitis media (ear infections).

Symptoms of Bacterial Conjunctivitis

• Thick, yellow-green or white pus discharge — the hallmark difference from viral conjunctivitis
• Eyelids stuck together upon waking due to dried discharge
• Redness in one or both eyes
• Swollen eyelids
• Mild to moderate discomfort or foreign body sensation
• Crusting along the eyelid margins

How Bacterial Conjunctivitis Is Treated

Bacterial conjunctivitis is treated with prescription antibiotic eye drops or ointment. Common options include:

• Fluoroquinolone eye drops — broad-spectrum antibiotics effective against most common bacterial causes
• Erythromycin ointment — often used for children and cases involving chlamydial or gonococcal infection
• Polymyxin B/trimethoprim drops — a commonly prescribed first-line combination antibiotic

Most patients see improvement within 24 to 48 hours of starting antibiotic treatment. The full course — typically five to seven days — should be completed even if symptoms resolve earlier to prevent recurrence and antibiotic resistance.

Viral vs. Bacterial Conjunctivitis: Key Differences

Distinguishing between viral and bacterial conjunctivitis is essential because the treatments differ. Key distinguishing features include:

• Discharge type — viral produces watery, clear discharge; bacterial produces thick, yellow-green pus
• Onset pattern — viral often starts in one eye and spreads to the other over days; bacterial may affect both eyes from the start
• Associated symptoms — viral is often accompanied by cold symptoms and swollen preauricular lymph nodes; bacterial may follow a sinus or ear infection
• Eyelid crusting — severe morning crusting with lids stuck shut is more typical of bacterial infection
• Treatment response — bacterial improves within 24 to 48 hours with antibiotics; viral must run its course over two to four weeks

How Conjunctivitis Is Diagnosed

At West Boca Eye Center, Dr. Brent Bellotte and the ophthalmology team diagnose conjunctivitis through:

• Patient history — recent cold symptoms, known exposure to an infected person, contact lens use, and timeline of symptom onset
• Slit-lamp examination — magnified inspection of the conjunctiva, cornea, and eyelid surfaces
• Discharge assessment — evaluating the type, color, and volume of discharge to differentiate viral from bacterial infection
• Lymph node palpation — checking for swollen preauricular lymph nodes, which point toward a viral cause
• Culture and sensitivity testing — in severe, recurrent, or treatment-resistant cases, a swab of the discharge may be sent to a laboratory to identify the specific organism and guide antibiotic selection

Preventing the Spread of Conjunctivitis

Infectious conjunctivitis spreads quickly, but these measures significantly reduce transmission:

• Wash hands frequently with soap and water — especially after touching the eyes or face
• Do not touch or rub your eyes
• Use separate towels, washcloths, and pillowcases — wash them daily in hot water
• Discard eye makeup used during or before the infection (mascara, eyeliner, eyeshadow)
• Do not share eye drops, cosmetics, or personal eye care items
• Discontinue contact lens wear until fully cleared by your ophthalmologist — discard the lenses and case you were using when symptoms began
• Stay home from work or school for at least 24 hours after starting antibiotic treatment (bacterial) or until symptoms improve (viral)
• Avoid swimming pools during active infection
• Clean frequently touched surfaces — doorknobs, phones, keyboards, light switches

When to See a Doctor for Pink Eye

While mild conjunctivitis sometimes resolves without treatment, schedule an evaluation at West Boca Eye Center if you experience:

• Moderate to severe eye pain (not just mild irritation)
• Thick pus discharge that returns quickly after cleaning
• Sensitivity to light that worsens or persists
• Vision changes or blurriness that does not clear with blinking
• Symptoms that do not improve after three days of prescribed treatment
• Pink eye in a newborn or infant — this requires urgent evaluation
• A weakened immune system or recent eye surgery

West Boca Eye Center is located at 9325 Glades Road, Suite 201, Boca Raton, FL 33434. Call (561) 488-1001 to schedule your appointment.

Frequently Asked Questions About Conjunctivitis

How long is pink eye contagious?

Viral conjunctivitis is contagious for 10 to 14 days from symptom onset. Bacterial conjunctivitis is generally considered non-contagious 24 hours after starting antibiotic treatment. Until then, strict hygiene measures are essential to prevent spreading the infection.

Can you get pink eye from a swimming pool?

Yes. Bacteria and viruses can survive in pool water, especially if chlorine levels are inadequate. Swimming during an active infection also risks spreading conjunctivitis to others. Avoid pools until your ophthalmologist confirms the infection has cleared.

Should I throw away my contact lenses if I get conjunctivitis?

Yes. Discard the lenses and the lens case you were using when symptoms began. Bacteria and viruses can adhere to lens surfaces and survive in the case even after cleaning. Start with a fresh pair and new case once your ophthalmologist clears you to resume wearing contacts.

Is pink eye always caused by an infection?

No. Conjunctivitis can also be caused by allergies (allergic conjunctivitis), chemical exposure, or foreign bodies in the eye. Allergic conjunctivitis is not contagious and is treated differently — typically with antihistamine drops rather than antibiotics. An eye exam is the best way to determine the cause.

When can my child return to school after pink eye?

For bacterial conjunctivitis, most schools allow children to return 24 hours after starting antibiotic eye drops, as long as there is no heavy pus discharge. For viral conjunctivitis, guidelines vary — consult your ophthalmologist and the school's health policy for specific guidance.

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