Eye Infection vs Allergy: What’s the Difference?

Learn when it could be allergic conjunctivitis or bacterial infection

A young Asian woman looks up as she puts eye drops into her right eye - SD Health Magazine

Learn when it could be allergic conjunctivitis or bacterial infection

With the change of seasons into spring comes beautiful weather and super blooms. But often Mother Nature also strikes with allergy symptoms that may bring you to tears. 

“Classically, we see a lot of eye issues during seasonal changes,” says Wade Licup, MD, a family medicine physician at Scripps Coastal Medical Center Vista. “It’s dependent on where you live, but here in San Diego, it’s usually spring and fall.” 

If you’re experiencing eye symptoms, such as itching, redness, discharge and more, you could be suffering from allergies or a bacterial infection, commonly known as pink eye. 

“Pink eye is the common term for conjunctivitis, or problems with the conjunctiva,” Dr. Licup explains. “This includes the lining of the eye and the white part — it’s what keeps the eye moist.” 

Allergic vs bacterial conjunctivitis

How do you know if it’s allergic conjunctivitis or bacterial conjunctivitis? The difference is in the symptomology, Dr. Licup says. 

Plus, while one usually clears up on its own, the other may require medical attention. Here’s how to tell the difference — and how to find relief.

What is allergic conjunctivitis? 


  • An allergen in the air: pollen, grass or other airborne allergens 
  • Animal dander, dust or other environmental allergens 
  • Not contagious 


  • Affects both eyes at the same time 
  • Itchy, gritty or burning sensation 
  • Mild swelling or redness 
  • Discharge or tears are watery and clear 


  • Most cases resolve on their own 
  • Symptom relief can come from over-the-counter antihistamines, anti-allergy and lubricant eye drops, cold compress  


  • Avoid allergic trigger if possible 
  • Wash hands often; wash face after contact with allergen 
  • If symptoms persist, you may want to undergo allergy testing  

What is bacterial conjunctivitis?


  • A contagious bacterial infection spread by contact with infected fluids from the eye 


  • Usually affects one eye at a time 
  • More severe itching, swelling and redness; may be accompanied by pain and sensitivity to light 
  • Discharge is more profound; could be thick, mucus-like, smelly 


  • May require medical attention 
  • Prescription medications, like antibiotic eye drops or ointment 


  • Practice good hand hygiene, washing hands often and avoiding touching your eyes 
  • Use clean face towels daily; change pillowcases often 
  • Pause use of eye makeup and discard makeup used during infection 
  • Wear glasses instead of contact lenses; practice good contact lens hygiene  

Eyelid inflammation

Another common eye condition that is often confused with pink eye or conjunctivitis is known as blepharitis, which is inflammation of the eyelid. Pink eye is an infection of the conjunctiva. Both cause eye discomfort and redness.

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This content appeared in San Diego Health, a publication in partnership between Scripps and San Diego Magazine that celebrates the healthy spirit of San Diego.

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