This is an old post I just discovered. I have both sinus problems (no allergies or asthma) and heartburn. I don't FEEL like I have acid reflux but can you have it and not know it?
I did a 2 week trial of Prilosec and for 10 weeks had no heartburn and no sinus problems. That's how I discovered they must be related. I was having a feeling of a lump in my throat that I couldn't clear, as many days as not. From sinus drainage I think. Using a sinus rinse helps. For a little while only.
After 10 weeks they both started coming back. I can only use the Prilosec every 14 weeks.
I'm not sure which causes which, but I read somewhere that mucus dripping down the back of the throat may inflame the stomach, causing acid to back up into the esophagus.
Then I also read the opposite--
When acid backs up, the body does certain things" in order to protect itself and one of the things is to produce extra mucus. The mucus will take away the caustic nature of the asset and neutralize the damage as well as stop the acid from spreading further up the esophagus. The funny thing is that sometimes when this is happening it actually stops the heartburn symptoms so you might not even know you're having acid reflux!"
Sue