What is follicular conjunctivitis? Symptoms, causes & treatment

Follicular conjunctivitis is inflammation of the conjunctiva characterized by lymphoid follicles on the tarsal and fornix conjunctiva, most evident in the inferior fornix. It is most commonly caused by adenoviral infection but also occurs with chlamydial infection, herpesviruses, molluscum contagiosum, and topical drug toxicity (medicamentosa). Symptoms include red eye, foreign-body sensation, tearing, and preauricular lymphadenopathy; discharge is usually watery, sometimes mucous. Diagnosis is clinical; targeted testing is used when chlamydia, herpesvirus, or atypical causes are suspected. Treatment is etiology-specific: supportive care for adenoviral disease; systemic antibiotics for chlamydial conjunctivitis; lesion eradication for molluscum; drug cessation for toxic causes; antivirals for herpetic disease.

Key Points

• Follicles are pale, dome-shaped lymphoid aggregates (0.5–1.5 mm) without a central vascular tuft, most prominent in the inferior palpebral and fornix conjunctiva.
• Adenovirus is the leading cause; chlamydia (adult inclusion conjunctivitis), molluscum contagiosum, topical medications, and herpesviruses are key differentials.
• Preauricular lymphadenopathy and watery discharge favor viral or chlamydial etiologies over bacterial or allergic disease.
• Laboratory testing is reserved for suspected chlamydia (nucleic acid amplification) or herpesvirus (PCR/culture), atypical or chronic cases, and neonatal disease.
• Treatment is guided by cause: avoid unnecessary topical antibiotics; use systemic azithromycin or doxycycline for chlamydia and remove eyelid molluscum lesions to resolve chronic unilateral follicular conjunctivitis.
• Consider short-course topical corticosteroids for severe adenoviral membranes or subepithelial infiltrates only after excluding herpes simplex keratitis.

Anatomy and Physiology

The conjunctiva is a mucous membrane lining the tarsal surfaces of the eyelids and reflecting onto the globe (bulbar conjunctiva), forming superior and inferior fornices. It contains conjunctival-associated lymphoid tissue (CALT) with lymphoid follicles. Follicles are germinal centers with proliferating B cells and plasma cells beneath an intact epithelium; they appear clinically as avascular, translucent elevations with surrounding vessels. Papillae, by contrast, are fibrovascular elevations with a central vascular tuft, typically reflecting allergic or bacterial inflammation.

Etiology

• Viral
  • Adenovirus: pharyngoconjunctival fever, epidemic keratoconjunctivitis (EKC) [1,2].
  • Herpes simplex virus (HSV): blepharoconjunctivitis, often unilateral [1].
  • Varicella-zoster virus (VZV): herpes zoster ophthalmicus with follicular conjunctivitis [1].
• Chlamydial
  • Chlamydia trachomatis serovars D–K: adult inclusion conjunctivitis; neonatal conjunctivitis [3,4].
  • Chlamydia trachomatis serovars A–C: trachoma (rare in the US; consider in migrants or travelers) [2].
• Molluscum contagiosum
  • Eyelid lesion shedding viral particles causing chronic unilateral follicular conjunctivitis [2].
• Toxic/medicamentosa
  • Topical antivirals, glaucoma medications (eg, brimonidine), miotics, preserved drops; systemic isotretinoin and others can contribute [2,5].
• Bacterial and zoonotic syndromes
  • Parinaud oculoglandular syndrome (eg, Bartonella henselae): granulomatous follicular conjunctivitis with ipsilateral preauricular node [6].
• Other
  • Rare hypersensitivity or autoimmune conditions may show follicles but typically have mixed patterns.

Pathophysiology

Exposure to viral or chlamydial antigens stimulates CALT, producing lymphoid follicle hyperplasia. Adenovirus infects conjunctival and corneal epithelium; in EKC, corneal epithelial involvement is followed by immune-mediated subepithelial infiltrates (SEIs). Chlamydia replicates intracellularly in conjunctival epithelium, causing chronic follicular reaction, superior epithelial keratitis, and pannus in persistent disease. Molluscum virions from an eyelid lesion chronically seed the ocular surface. Toxic conjunctivitis results from epithelial toxicity and delayed hypersensitivity to medications or preservatives, often with punctate keratitis. HSV and VZV cause lytic infection of skin and mucosa, with unilateral follicular response and risk of corneal involvement.

Epidemiology

• Adenoviral conjunctivitis accounts for the majority of infectious conjunctivitis in adults in the US and frequently presents with follicles [1,7].
• Adult inclusion conjunctivitis is underrecognized; prevalence is higher in sexually active young adults and mirrors urogenital chlamydia epidemiology [3,4,7].
• Neonatal chlamydial conjunctivitis occurs in 2–23 per 1,000 live births in settings without prenatal screening; US rates are lower due to routine screening and treatment [3].
• Molluscum contagiosum–related ocular disease is uncommon but occurs in children and immunosuppressed adults [2].
• Toxic conjunctivitis is prevalent among chronic topical medication users (eg, glaucoma) and with benzalkonium chloride exposure [5].

Classification

• By cause: viral (adenovirus, HSV, VZV), chlamydial (adult inclusion, neonatal, trachoma), molluscum-related, toxic/medicamentosa, oculoglandular.
• By course: acute (<4 weeks) vs chronic (≥4 weeks), with chronicity typical of chlamydia, molluscum, and toxic etiologies.
• By laterality: unilateral (often HSV, molluscum, early chlamydia) vs bilateral (common in adenovirus; chlamydia often becomes bilateral).

Symptoms and Signs

• General features (most variants)

  • Redness, foreign-body sensation, burning, tearing, mild photophobia.
  • Watery to mucoid discharge (mucopurulent suggests chlamydia).
  • Follicles on inferior tarsal/fornix conjunctiva; surface appears pebbled without central tufts.
  • Preauricular or submandibular lymphadenopathy (especially viral, chlamydial).

• Adenoviral follicular conjunctivitis/EKC

  • Acute onset, often bilateral sequential.
  • Pharyngitis, fever, or tender nodes (pharyngoconjunctival fever).
  • Punctate epithelial keratitis; SEIs at 1–2 weeks causing photophobia and glare.
  • Pseudomembranes; hemorrhagic conjunctivitis in some serotypes [1,2].

• Chlamydial (adult inclusion conjunctivitis)

  • Subacute, often unilateral then bilateral; persists >3–4 weeks.
  • Mucopurulent discharge, stringy mucus, crusting; superior epithelial keratitis and peripheral pannus can occur.
  • Concomitant urethritis/cervicitis; sexual exposure history [3,4].

• Neonatal chlamydial conjunctivitis

  • Onset 5–14 days after birth; chemosis, eyelid swelling, mucopurulent discharge; risk of chlamydial pneumonia [3].

• HSV blepharoconjunctivitis

  • Unilateral, vesicular lid lesions, follicular conjunctivitis; risk of dendritic keratitis [1].

• VZV (herpes zoster ophthalmicus)

  • Dermatomal vesicular rash; follicular conjunctivitis, keratitis, and uveitis can occur [1].

• Molluscum contagiosum–related

  • Chronic unilateral follicular conjunctivitis; look for small umbilicated lid lesion(s); diffuse punctate keratitis common [2].

• Toxic/medicamentosa

  • Chronic burning/irritation; follicular reaction with punctate epitheliopathy; often bilateral; history of chronic topical medication use (eg, brimonidine) or preserved drops [5].

• Parinaud oculoglandular syndrome

  • Unilateral granulomatous conjunctivitis with prominent preauricular node; cat exposure suggests Bartonella [6].

Complications

• Corneal involvement: punctate keratitis and SEIs in EKC; dendritic/geographic ulcers in HSV; pseudodendrites in VZV; peripheral pannus in chlamydia [1–4].
• Pseudomembranes and membranes causing conjunctival scarring, symblepharon (rare) [1,2].
• Chronic conjunctivitis with scarring in trachoma (rare in US) [2].
• Secondary dry eye from surface inflammation.
• Transmission within households, schools, and clinics (adenovirus) [1,2].

Diagnosis

Clinical evaluation

• History: onset, laterality, exposure to ill contacts/swimming pools, recent upper respiratory infection, sexual history, perinatal history, medication use (topical and systemic), contact lens wear, skin lesions, and systemic symptoms.
• Examination: visual acuity; external inspection for lid lesions (molluscum, HSV/VZV); preauricular nodes; slit-lamp exam of tarsal/fornix conjunctiva for follicles vs papillae; corneal staining for epithelial disease; look for membranes/pseudomembranes.
• Red flags for alternative or coexisting pathology: moderate to severe pain, photophobia, reduced vision, corneal staining defects, marked purulence, unilateral severe disease in contact lens wearer.

Imaging and laboratory testing

• Adenovirus: point-of-care antigen detection (eg, lateral flow immunoassay) can support diagnosis; clinical sensitivity varies and negative results do not exclude disease [1,7].
• Chlamydia: nucleic acid amplification test (NAAT) on conjunctival swab is preferred when available via validated laboratory-developed testing; culture or direct fluorescent antibody are alternatives. Test and treat sexual partners; screen for other STIs per CDC [3,4].
• HSV/VZV: PCR or viral culture of conjunctival/corneal scrapings when herpetic disease suspected [1].
• Neonatal: obtain ocular swab for chlamydia NAAT/culture; evaluate for concurrent pneumonia [3].
• Consider bacterial culture if hyperacute purulent discharge (eg, gonococcus) or severe disease.

Differential diagnosis

Treatment

Medical management

Management is cause-specific; avoid empiric topical antibiotics for presumed viral disease.

• Adenoviral follicular conjunctivitis/EKC

  • Supportive care: cold compresses, preservative-free artificial tears qid–hourly as needed; topical antihistamine/mast-cell stabilizer (eg, olopatadine 0.1% bid) for itching [1,2].
  • Short-course topical corticosteroids (eg, loteprednol 0.2–0.5% qid taper over 1–2 weeks) for visually significant membranes or dense SEIs, after excluding HSV keratitis. Off-label; improves symptoms but does not shorten disease or viral shedding [1,2].
  • Remove membranes and consider topical antibiotic prophylaxis if epithelial defects are present [1].
  • Counsel on contagion and hygiene; no role for systemic antivirals.

• Chlamydial (adult inclusion conjunctivitis)

  • Azithromycin 1 g PO once (single-dose therapy) or doxycycline 100 mg PO bid for 7 days; both are CDC-recommended regimens [3,4].
  • Alternatives: erythromycin base 500 mg PO qid for 7 days [3].
  • Treat sexual partners; test for other STIs; topical antibiotics are unnecessary adjuncts.

• Neonatal chlamydial conjunctivitis

  • Erythromycin base or ethylsuccinate 50 mg/kg/day PO divided q6h for 14 days; monitor for infantile hypertrophic pyloric stenosis [3].
  • Evaluate and treat mother and partners; assess for chlamydial pneumonia.

• HSV blepharoconjunctivitis

  • Supportive care for mild disease; if corneal involvement or extensive skin lesions, oral acyclovir 400 mg PO five times daily for 7–10 days or valacyclovir 1,000 mg PO tid for 7 days; topical ganciclovir 0.15% gel 5x/day for epithelial keratitis per FDA label [1].
  • Avoid topical corticosteroids unless directed by an ophthalmologist with concurrent antiviral coverage.

• VZV (herpes zoster ophthalmicus)

  • Oral valacyclovir 1,000 mg PO tid for 7 days or acyclovir 800 mg PO five times daily for 7–10 days, ideally within 72 hours of rash onset; consider adjunct topical lubricants [1].

• Molluscum contagiosum–related

  • Treat eyelid lesion(s) by curettage, cryotherapy, or excision; resolution of conjunctivitis typically follows lesion removal [2].
  • Lubricants and short-course mild topical steroids may be used for surface inflammation.

• Toxic/medicamentosa

  • Discontinue offending agent and switch to preservative-free alternatives when possible; lubricants, cold compresses, and short-course mild topical steroid (eg, loteprednol 0.2% bid–qid for 5–10 days) may be used [5].

• Parinaud oculoglandular syndrome (suspected Bartonella henselae)

  • Oral azithromycin (adult: 500 mg day 1, then 250 mg daily for 4 days) can shorten lymphadenopathy; severe cases may need doxycycline +/- rifampin per infectious disease guidance [6]. Off-label in ocular disease.

Note: Doxycycline is contraindicated in pregnancy and in children <8 years; use azithromycin or erythromycin instead [3,4].

Procedural and surgical management

• Removal of conjunctival pseudomembranes with cotton-tipped applicator or forceps to reduce scarring and discomfort; consider placement of a bandage contact lens for large epithelial defects with close follow-up [1].
• Eyelid lesion eradication for molluscum contagiosum (eg, curettage or cryotherapy) [2].
• Trachoma-related scarring (rare in US): eyelid surgery for trichiasis when present (specialty referral) [2].
• Representative CPT codes (contextual):
  • 67840: Excision of lesion of eyelid, not involving lid margin, when removing molluscum lesions.
  • 67850: Destruction of eyelid lesion(s), except chalazion.

Special populations

• Pediatric: Adenoviral disease is common and highly contagious; exclude from school/daycare while eyes are tearing and matted. Neonatal chlamydial conjunctivitis requires systemic therapy and pediatric follow-up for pneumonia [1,3].
• Pregnancy/lactation: Prefer azithromycin for chlamydia; avoid doxycycline. Most topical lubricants and antihistamines have minimal systemic absorption; use the lowest effective potency steroid only if necessary [3,4].
• Immunocompromised: More severe or prolonged adenoviral and herpetic disease; lower threshold for virologic testing, antiviral therapy, and ophthalmology referral [1].

Prognosis

• Adenoviral follicular conjunctivitis resolves in 1–3 weeks; SEIs may persist for weeks to months and can fluctuate [1,2].
• Adult inclusion conjunctivitis responds promptly to systemic antibiotics; untreated cases can persist for months with corneal involvement and transmission risk [3,4].
• Molluscum-related disease resolves after lesion eradication.
• Toxic conjunctivitis improves within days to weeks after discontinuation of the culprit agent.
• Herpetic disease prognosis depends on corneal involvement; prompt antiviral therapy reduces complications [1].

Prevention and Patient Counseling

• Hand hygiene, avoidance of eye rubbing, and not sharing towels, makeup, or contact lens accessories decrease transmission.
• Stay home from work/school during the period of active tearing and matting; adenovirus can remain contagious for 10–14 days [1,2].
• Disinfect instruments and surfaces in clinical settings; follow contact precautions during outbreaks [1].
• Suspend contact lens wear during active conjunctivitis; replace or disinfect lenses and cases before resuming.
• For chlamydial disease, ensure partner notification and treatment; abstain from sexual activity for 7 days after single-dose azithromycin or until completion of doxycycline and symptom resolution [3,4].

When to Seek Immediate Care

• Sudden drop in vision, severe light sensitivity, or severe eye pain.
• A contact lens wearer with a red, painful eye.
• Blistering rash on the eyelids, forehead, or nose with a red eye.
• A newborn with swollen eyelids and pus-like discharge.
• Large sheets/membranes on the inside of the eyelids or bleeding when they are removed.
• Worsening redness, swelling, or discharge after starting treatment.

References

1. Azari AA, Barney NP. Conjunctivitis: A Systematic Review of Diagnosis and Treatment. JAMA. 2013;310(16):1721-1729. doi:10.1001/jama.2013.280318.
2. American Academy of Ophthalmology. Viral Conjunctivitis. EyeWiki. Accessed July 2026. https://eyewiki.aao.org/Viral_Conjunctivitis
3. Centers for Disease Control and Prevention. Chlamydial Infections – STI Treatment Guidelines, 2021. Updated 2021. https://www.cdc.gov/std/treatment-guidelines/chlamydia.htm
4. American Academy of Ophthalmology. Chlamydial Conjunctivitis. EyeWiki. Accessed July 2026. https://eyewiki.aao.org/Chlamydial_Conjunctivitis
5. American Academy of Ophthalmology. Medicamentosa (Toxic Conjunctivitis). EyeWiki. Accessed July 2026. https://eyewiki.aao.org/Medicamentosa_(Toxic_Conjunctivitis)
6. Klotz SA, Ianas V, Elliott SP. Cat-scratch Disease. Am Fam Physician. 2011;83(2):152-155. PMID: 21243990.
7. Cronau H, Kankanala RR, Mauger T. Diagnosis and Management of Red Eye in Primary Care. Am Fam Physician. 2010;81(2):137-144. PMID: 20082511.

This article is for informational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified eye care professional about your specific condition. If you have sudden vision loss, severe eye pain, or an eye injury, seek emergency care immediately.