What are the causes of bilateral conjunctivitis, excluding adenoviral (Adeno) infection, and is it contagious to others?

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Last updated: April 22, 2025View editorial policy

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From the Guidelines

Bilateral conjunctivitis is most likely caused by an infectious agent, with viral causes being the most common and highly contagious, and treatment should be focused on addressing the underlying cause while taking measures to prevent transmission. The causes of bilateral conjunctivitis can be classified into infectious and non-infectious types, with infectious causes including bacterial, viral, and chlamydial infections 1. If adenovirus has been ruled out, other contagious pathogens such as herpes simplex virus, enterovirus, or chlamydial infection should be considered 1. Non-infectious causes include allergic conjunctivitis, contact lens-related irritation, chemical exposure, and systemic conditions like Stevens-Johnson syndrome.

Some key points to consider in the diagnosis and management of bilateral conjunctivitis include:

  • Identifying the underlying cause of the conjunctivitis, whether it be infectious or non-infectious, to guide treatment decisions 1
  • Considering the potential for person-to-person transmission and taking measures to prevent the spread of infection, such as strict hand hygiene and avoiding sharing of personal items 1
  • Recognizing the clinical signs and symptoms associated with different types of conjunctivitis, such as the presence of follicles or purulent discharge, to aid in diagnosis 1
  • Providing supportive care and treatment based on the underlying cause, such as antibiotic eye drops for bacterial infections or antihistamine drops for allergic conjunctivitis 1

In terms of prevention and transmission, it is essential to advise patients to practice strict hand hygiene, avoid sharing towels or pillows, avoid touching their eyes, and stay home from work or school until discharge resolves, typically 24-48 hours after starting antibiotics for bacterial causes 1. By taking a comprehensive approach to diagnosis and management, and prioritizing measures to prevent transmission, healthcare providers can effectively address bilateral conjunctivitis and improve patient outcomes.

From the Research

Causes of Bilateral Conjunctivitis

  • Bilateral conjunctivitis can be caused by various factors, including viral, bacterial, and allergic reactions 2, 3, 4, 5, 6
  • Viral conjunctivitis is the most common overall cause of infectious conjunctivitis and is usually self-limiting 3, 5
  • Bacterial conjunctivitis is the second most common cause of infectious conjunctivitis and can be caused by bacteria such as Neisseria gonorrhoeae or Chlamydia trachomatis 2, 3
  • Allergic conjunctivitis is encountered in up to 40% of the population and is characterized by itching, mucoid discharge, chemosis, and eyelid edema 3, 6

Transmission of Conjunctivitis

  • Conjunctivitis can be transmitted through hand-to-eye contact, ocular secretions, respiratory droplets, and contact with ophthalmic care providers and their medical instruments 5
  • Strict personal hygiene, including frequent handwashing, is essential to decrease the risk of transmission 4

Diagnosis and Treatment

  • A comprehensive history and physical examination can guide diagnosis, but culture is occasionally necessary to establish the diagnosis or to guide therapy 2, 4
  • Treatment for viral conjunctivitis is mostly supportive, while bacterial conjunctivitis may require topical antibiotics 3, 4
  • Allergic conjunctivitis can be treated with topical antihistamines and mast cell stabilizers 3, 4

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Conjunctivitis.

American family physician, 1998

Research

Conjunctivitis: Diagnosis and Management.

American family physician, 2024

Research

Adenoviral keratoconjunctivitis.

Survey of ophthalmology, 2015

Research

Conjunctivitis: A Systematic Review.

Journal of ophthalmic & vision research, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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