Allergic conjunctivitis usually begins to improve within 24 to 72 hours once you start treatment and avoid the allergen, though it can last as long as you are exposed to the trigger. For quick relief, I recommend over-the-counter antihistamine eye drops containing ketotifen or olopatadine. Lubricating artificial tears are also excellent for flushing out allergens and soothing irritation. If you have nasal symptoms, oral antihistamines like cetirizine can help. Please avoid rubbing your eyes, as this worsens inflammation. If symptoms persist beyond a few days or you experience vision changes, please consult an eye specialist for prescription-strength drops.