USE a steroid nasal spray and antihistamine at the same time:

This is because they work better together. But before you administer the steroid nasal spray, you can also use a nasal spray that contains sea salt, such as Sterimar Hayfever and Allergies Nasal Hygiene spray (100ml, €11.99, boots.ie). The salt spray can help dilute pollen and wash it away. Use a sea salt spray three to four times a day.