The science behind why only one nostril clogs when you’re sick

Your nose is smarter than you think

Being stuffed up sucks. Ever wonder why it seems like one nostril feels way more clogged than the other? It’s not just your imagination: There’s a scientific reason behind it.

Credit a physiological response called the nasal cycle, a process where your nostrils take turns sucking in more air, says Rachel Roditi, M.D., a surgeon in the division of otolaryngology at Brigham and Women’s Hospital. Find out why your nostrils play tag team—and what you can do when one side’s all jammed up.

Why One Nostril Gets More Congested

Structures in both sides of your nose called inferior turbinates are responsible for warming and humidifying air before it reaches your lungs, says Dr. Roditi. This protects your lungs by reducing dryness and irritation. That process is a lot of work. So your nose funnels its resources more to one side than the other to make the process more efficient.

It sends more blood flow to one nostril, which warms the air coming in through there, but also causes the turbinate on that side to swell. That swelling means there’s less room for air to make its way in. It’s pretty subtle, though—unless you have a cold, infection, allergies, or a structural problem like a deviated septum, you probably won’t notice it going on.

But when you are sick, blood flow to your nose increases even more, sparking more swelling and greater mucus production in your nasal region, says Dr. Roditi. Even though you’re congested throughout your entire nose, you feel it more strongly in the one nostril where the turbinate is already swollen as part of the normal nasal cycle.

How to Treat Your Congestion

There’s really nothing you can do to shut off the nasal cycle, says Dr. Roditi. It’s likely that one nostril will always feel more stuffed up than the other when you’re sick. Still, after about 90 minutes to 4 hours, your nose switches sides. When that occurs, you’ll probably feel some relief when the swelling in the one nostril goes down—but then the other side will start to feel clogged instead.

Your best bet is to work on easing the congestion overall. Steam from a hot shower or humidifier can help open the floodgates, says Dr. Roditi. And saline nasal sprays can help flush out mucus, too.

Consider topical nasal congestion sprays with oxymetazoline, like Afrin which constricts blood vessels—more of a last resort, says Jonathan A. Bernstein, M.D., an associate professor at the University of Cincinnati and editor-in-chief of the Journal of Asthma. “These sprays can cause rebound congestion,” he says. That means your nose becomes addicted to them, and relies on them to open up.

If you must use them, stick to two puffs a day for no more than five to seven days, he says. If your stuffed-up symptoms persist beyond 10 to 14 days, or you notice nasal congestion at times other than when you’re sick, check in with your doctor to make sure that something bigger—like a deviated septum—isn’t at play, says Dr. Roditi.