Is It Safe To Give My Toddler With Autism Fenistil Drops Daily For Nighttime Nasal Blockage?

Hi my question is my daughter can t sleep in night because of her noses block I gave her fenistil drops on night she started yo sleep is it ok to give her every day she is now 4 and half years and also has Diagnose autism vould you please let me know what is good to give her thank you