Why Does Only One Nostril Get Stuffy When You’re Sick?
It never fails. The moment we have a wild swing in temperatures, which tends to happen frequently because we live in the Midwest, my sinuses go into overdrive which, as you can see by the size of the schnoz on my face (that's me in the picture above, 👋) can produce enough mucous for an entire army of noses. The snot factory will remain open 24 hours a day, seven days a week until the temperature remains in the same range for a few days. Even once that happens, it scales back production a bit, but it never completely shuts it down. And outside of constantly taking a decongestant, there's not a darn thing I can do about it. When I see the forecast show a drastic temperature change coming, all I can do is make sure I keep a box of tissues nearby. It is what it is. What I never have understood though is why it only happens on one side of my freakin' nose.
Turns out, there's quite a bit more going on than just passing air in and out of your lungs inside those two wind tunnels on your face.
After literally searching, "why does my nose only get stuffy on one side," I found the reason. It's all thanks to the same soft tissue that, uh, let's say, makes a man's soldier stand up and salute. Seriously.
A Literal Open and Shut Case
While you're sitting around, minding your own business, breathing in and out without thinking about it to keep yourself alive, your body's autonomic nervous system, which also controls several internal functions like heart rate and digestion without any thought on your part, is keeping your lungs safe from dry, harsh air by warming and humidifying it with the mucous it creates in your nose. The process takes quite a bit of work, so to protect itself from overworking, your nose alternates between which nostril is taking in more air by performing what science calls a "nasal cycle." In order to reduce the amount of air going in and out of the nostril it's giving a break, it pumps extra blood into the soft, a.k.a. erectile, tissue inside the sinus cavity. The tissue swells, limiting the amount of air that can pass through that side. Basically, it gives it a sinus boner. After a few hours, it relaxes and repeats the process on the other side. This happens every day for our entire lives.
It's a pretty impressive process, especially since it happens without our knowledge and has been happening since the day we took our first breath. But, it's not without its flaws. The nasal cycle doesn't care if your sinuses are already a bit swollen because your immune system is trying to fight off an illness or allergy to something in the air. Just like a good worker bee, all it knows is to shut down one side and open the other over and over and over again until you die.
As you may have guessed by now, with the already limited space in your sinus cavity, the additional swelling causes even less, or if there's enough swelling no, air to pass through, leaving you one stuffy or completely clogged nostril.
[Sources: Science Alert / Encyclopedia Britannica]
Goosebumps and other bodily reactions, explained