What is the cause of a 1-week duration of left eye redness, accompanied by pain, itching, and swelling, which began concurrently with seasonal allergies, in a patient who has been using Benadryl (diphenhydramine) and Zyrtec (cetirizine) with no relief?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: May 5, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

Differential Diagnosis for 1 Week of Eye Redness

  • Single most likely diagnosis
    • Allergic conjunctivitis: The patient's symptoms of redness, pain/itching, and swelling began with their seasonal allergies, and they have not found relief with oral antihistamines (Benedryl and Zyrtec). This suggests an allergic reaction, likely to pollen or other environmental allergens.
  • Other Likely diagnoses
    • Dry eye syndrome: Although the patient denies morning crusting/discharge, dry eye could still be a contributing factor, especially if their allergies are exacerbating the condition.
    • Blepharitis: This condition involves inflammation of the eyelids and could cause redness, itching, and swelling, although it often presents with crusting or discharge, which the patient denies.
    • Viral conjunctivitis: While the patient's symptoms began with their seasonal allergies, it's possible that they have a viral infection, which could cause similar symptoms.
  • Do Not Miss diagnoses
    • Acute angle-closure glaucoma: Although the patient denies vision changes, this condition can cause severe eye pain, redness, and swelling, and is an emergency that requires prompt treatment.
    • Orbital cellulitis: This is a bacterial infection of the tissues surrounding the eye, which can cause redness, swelling, and pain, and can lead to serious complications if not treated promptly.
    • Herpes simplex keratitis: This is a viral infection of the cornea that can cause eye redness, pain, and vision changes, and can lead to serious complications if not treated promptly.
  • Rare diagnoses
    • Sjögren's syndrome: This is an autoimmune disorder that can cause dry eye and other symptoms, but it is relatively rare and would not typically present with acute onset of symptoms.
    • Sarcoidosis: This is an inflammatory disease that can affect the eyes, but it is relatively rare and would not typically present with acute onset of symptoms related to seasonal allergies.

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.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.