Allergies are miserable, and what makes them even more miserable is when just a single nostril gets congested. You can sort of breath but not really, and there seems to be no helping that one side of your nose. But why does it happen?
Surprise, your nose is always doing some iteration of this, and it’s called the nasal cycle.
Men’s Health spoke with Rachel Roditi, M.D, an otolaryngologist, who explained that you have structures in your nose called inferior turbinates. They’re important because they help protect your lungs by warming and humidifying air to prevent dryness and irritation. The process of warming and humidifying, though, is hard work so to make it more efficient the work goes to one of your nostrils more than the other.
The nostril working a bit harder has more blood flowing to it which causes the turbinate to swell, and when that happens, there’s less room for air. Typically, you wouldn’t notice this, but when you’re congested, more blood flow goes to your nose causing that same turbinate to swell even more. That’s why it seems like one nostril is more congested than the other.
As for what to do about it, well, there’s not really a way to treat just one nostril. You’ve got to treat the congestion as a whole. You can’t shut off the nasal cycle which is always occurring whether you’re sick or not.
The next time you’ve only got one nostril stopped up, your best bet is to use your usual cold or allergy remedies and ride it out.