Allergic reaction can cause eye itching, swelling and watering. To reduce the allergic reaction, you need to get out of touch with possible allergens. Get good ventilation and fresh air in. Use an air cleaner to filter the dust and allergens and an humidifier to add moist to air which can relieve the itching and dryness of eyes. Use some water to flush the eyes, washing possible allergens or irritants out of eyes. Because it is caused by allergy, once you are out of touch with the allergen, the reaction would be alleviated and it would clear out very soon. To speed up your recovery, you could apply some cold compress on eyes. Don't worry too much. If your symptoms persist and worsen as time goes, you should go to hospital immediately for proper treatment.