What are the common causes of conjunctivitis?

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Last updated: February 17, 2025View editorial policy

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From the FDA Drug Label

INDICATIONS AND USAGE: For the treatment of superficial ocular infections involving the conjunctiva and/or cornea caused by Bacitracin susceptible organisms. INDICATIONS AND USAGE For the treatment of superficial ocular infections involving the conjunctiva and/or cornea caused by organisms susceptible to erythromycin.

The common causes of conjunctivitis are bacterial infections, including those caused by Bacitracin susceptible organisms and organisms susceptible to erythromycin, such as:

  • N. gonorrhoeae
  • C. trachomatis 1 2

From the Research

Introduction to Conjunctivitis

Conjunctivitis, an inflammation of the conjunctiva, can be caused by various factors including infectious and non-infectious etiologies. The common causes of conjunctivitis are multifaceted and can be broadly categorized into viral, bacterial, and other types.

Viral Conjunctivitis

Viral conjunctivitis is the most common type of conjunctivitis, predominantly caused by adenoviruses, enteroviruses, and herpes viruses 3, 4. It is highly contagious and can lead to significant morbidity. Symptoms of viral conjunctivitis include swelling of the lid margin, ciliary injection, and serofibrinous eye discharge. Preauricular lymph node swelling can also occur.

Other Causes of Conjunctivitis

Other causes of conjunctivitis include:

  • Chlamydial conjunctivitis, which is dominated by trachoma and can lead to infectious blindness 4
  • Bacterial conjunctivitis, which can be caused by various bacteria
  • Allergic conjunctivitis, which is an immune-mediated response to allergens

Diagnosis and Treatment

Diagnosis of conjunctivitis is usually made based on clinical presentation, and rapid tests or PCR diagnostics can be used for confirmation 5. Treatment of conjunctivitis depends on the underlying cause and can include:

  • Symptomatic treatment with artificial tears and antibiotic eye drops for secondary bacterial infections
  • Local and systemic virostatic therapy for certain viral infections
  • Topical corticosteroids, which can be useful in treating ocular inflammation, but should be used with caution due to potential risks 6
  • Avoiding touching the eyes, washing hands frequently, and using disposable towels to minimize transmission

Differential Diagnosis and Caveats

Differential diagnosis of conjunctivitis includes:

  • Herpes simplex viral conjunctivitis, which requires careful diagnosis to avoid using corticosteroid eye solution 3
  • Chlamydial conjunctivitis, which can be associated with sexually transmitted diseases
  • Allergic conjunctivitis, which can be treated with anti-allergic medications

It is essential to recognize the affection of corneal or intraocular structures early to initiate adequate and effective therapy, as untreated conjunctivitis can lead to temporary or permanent impairment of vision 5.

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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