Hi there, Thank you for choosing HCM for your query. Will gladly answer your question. As you mentioned that your grandson who is now 11 months has had a problem with blocked nostrils since birth which is taken care with spray you are using. Most likely the spray is saline. There are several possibilities for your grandson to have both nostrils blocking on a daily basis for such a long duration of time. 1. If anyone in the family smokes, kids are more prone to have a increased risk of allergies/asthma/chronic rhinitis/sinusitis. 2. If there is dry air circulating in the house. 3. If you donot have a good chimney in the house or there is smoke or carbon monoxide exposure from the stove you use. 4. If there are pets in the house and your grandson has a tendency towards allergy. 5. If you have carpets in the house and they are cleaned with dry vaccuming. 6. If there is mold in the house. To prevent your grandson from getting chronic nasal blockage or chronic rhinitis , I would suggest you follow some simple measures and see if that provides some relief. 1. Keep your pets outside for a while if possible. 2. Use a good chimney if you donot have one. 3. All smokers in the house should smoke outside and wash their hands and change their clothes before they touch the baby. 4. Carpets should be cleaned using a wet vaccum. 5. Have the mold in the house removed. 6. If your house air is very dry, you can use a humidifier but make sure its cleaned thoroughly since mould can grow in it if it is not cleaned on a regular basis. If even after following the measures above, you are concerned or there is no relief in your grandson s symptoms, then have him examined by his pediatrician or an ENT specialist. Hope this helps. Regards, Dr. Sumeet.