Allegra Nasal Spray is a steroid. It relieves the symptoms of allergic rhinitis such as runny nose, sneezing and sinus discomfort. It works by blocking the production of certain chemical messengers that cause inflammation (swelling) and allergies, thus relieving the discomfort and irritation in your nose. You should always use it as advised by your doctor but to get the full benefit you should take it regularly. It may take a few days for the spray to take full effect. If you do not see an improvement in your symptoms after a week you should talk to your doctor. The most common side effects of Allegra Nasal Spray include nasal discomforts such as burning or itching. It can also cause nosebleeds, nasal inflammation, and headaches in some patients. Talk to your doctor if you are worried about side effects or they do not go away. This medicine may lower the ability of your body to fight off infections, so try to stay away from someone having chickenpox, measles, or tuberculosis. In general, you should try to avoid situations which make your symptoms worse (things like pollen and dust mites), and it would be best to avoid smoking. Before starting to use this medicine you should let your doctor know if you are pregnant or breastfeeding, discuss the risks and benefits with your healthcare team. If you use this medicine for a long time, your doctor may want to carry out certain medical tests during the duration of treatment to check your progress.