How can I relieve eyes that sting because of allergies?

Allergy eye drops. Allergy eye drops (topical) are the most effective. Some are over-the-counter (e.g. Zaditor), while other require a prescription (e.g. Pataday, optivar, etc.). Oral antihistamines can help as well.
Allergy eye drops. Although you can achieve some relief of allergy eye symptoms with oral antihistamines, allergy eye drops are far more effective. Medications such as zaditor, patanol, pataday, Bepreve (bepotastine besilate) and Optivar can be very effective at relieving allergy eye symptoms.