The answer to this depends on what you mean by nasal spray. There are some nasal sprays which are just saline water, and these are totally safe. Similarly, nasal irrigation systems, such as the Nettipot, are quite safe and are very useful for clearing up nasal allergies and sinus congestion.
On the other hand, if you mean a spray that is labeled as a "nasal decongestant" then you need to be careful. Nasal decongestants are medications that work by decreasing the flow of blood to the nasal lining. Although they are instantly effective, they should only be used for no more than 3 days before discontinuing them. This is because, if you continue to use them, your body will actually adapt to the medication and something called rebound congestion will occur - paradoxically, using the decongestant will actually make you more congested!
If your symptoms of sinus congestion have been going on for more than a week or so, you may want to see your primary care doctor
. They will be able to evaluate your symptoms, and they can offer you additional prescription medication options that will potentially help to clear up your symptoms more quickly.
I hope you are feeling better soon!