Steriod nasal spray- how long does it take to work for sinus headache?

Steroid nasal sprays. While steroid nasal sprays may have some activity on reducing nasal inflammation as soon as 12 hours after a single dose, they don't achieve their maximum effect for several days. If you are having nasal congestion causing a sinus headache, you may need to take an oral or intranasal decongestant or antihistamine to get more temporary relief while the steroid spray takes effect.