Allergies. Pollen counts are hitting record highs, making allergies worse than ever. Start with over the counter antihistamines; if that isn't enough, see your dr about a nasal steroid spray; if that still doesn't add enough relief, singulair (montelukast) may help. If you're really bad, a short course of Prednisone can help temporarily.
May not be hay fever. Sometimes what people think are nasal symptoms due to allergies or hayfever are in reality symptoms due to an unrecognized sinus infection. If these medications are not giving you relief it might be worthwhile seeing an ENT doctor for evaluation of your nose and sinuses possibly including a therapeutic trial of antibiotics.
Hayfever. Nasal saline spray helps remove allergens from nose. Zyrtec & Allegra work well. If nasal congestion is bad, then try sudafed or allegra-d, etc. Prescriptions like nasal steroids (i.e., flonase, rhinocort) or nasal antihistamine sprays (astepro) work well. Steroid shots or pills may work great but should be used no more than 1-2 times/yr. Visine allergy or Pataday (rx) for burn, itch eyes.
Hayfever. With allergies, the first line of treatment is avoidance. Pollen is highest in the ams and on windy days. Keep windows closed. In car, use ac on recirculated. Wear a mask if mowing grass, etc. When return home, change clothes, shower and use nasal saline to clean out allergens from nose. If avoidance and meds are not successful, immunotherapy shots may help.