Your tear ducts are a drainage system that moves tears from the surface of your eye into your nasal cavity. Every time you blink, a small pumping mechanism pushes tears through a series of tiny channels, collecting them in a sac near the bridge of your nose and funneling them downward into your nose. That’s why your nose runs when you cry.
Where Tears Come From
Not all tears originate in the same place. Basal tears, the thin layer that keeps your eyes moist and nourished around the clock, come from small accessory glands tucked under your eyelids. Reflex tears and emotional tears come from the main lacrimal glands, which sit in the upper outer corner of each eye socket. When something irritates your eye (dust, onion fumes, wind), sensory nerve endings on the eye’s surface trigger those glands to flood the eye with fluid that washes away and chemically neutralizes whatever is threatening the surface.
All three types of tears are mostly water, plus electrolytes, proteins, and mucins that help the fluid spread evenly across the eye. Once tears have done their job on the surface, they need somewhere to go. That’s where the drainage system takes over.
The Drainage Path, Step by Step
If you pull down your lower eyelid slightly and look in a mirror, you can spot a tiny dot near the inner corner of the eye. That’s the punctum, a drainage opening only 0.2 to 0.3 millimeters wide. You have one on each eyelid, upper and lower, for a total of four.
Each punctum leads into a short vertical channel about 2 millimeters long called a canaliculus. This channel runs perpendicular to the eyelid margin before widening slightly and making a sharp 90-degree turn toward the nose. It then continues horizontally for another 8 to 10 millimeters, following the curve of the eyelid. In about 90% of people, the upper and lower canaliculi merge into a single common channel before reaching the lacrimal sac. In the remaining 10%, they enter the sac independently.
The lacrimal sac sits in a small bony groove near the bridge of your nose. From there, tears flow downward through the nasolacrimal duct, a channel that runs through the maxillary bone at a slight downward angle of 15 to 30 degrees. The duct opens into the nasal cavity beneath the inferior turbinate, a bony shelf inside the nose. A small tissue flap at the opening, called the valve of Hasner, prevents air and nasal contents from traveling back up into the eye.
How Blinking Pumps Tears Through
Tears don’t just trickle passively into the drainage system. Your eyelids act as a pump, and every blink powers the cycle.
When your eyelids close, the muscle around the eye (the orbicularis) contracts. This squeezes the canaliculi shut, pushing whatever tears are already inside them into the lacrimal sac. At the same time, the contraction pulls the upper wall of the sac outward, creating a drop in pressure that sucks tears in from the canaliculi. Meanwhile, the lower portion of the sac wall presses inward, building positive pressure that forces tears already in the sac downward through the nasolacrimal duct and into the nose.
When your eyelids open, the muscle relaxes. The canaliculi spring back open, creating negative pressure that draws fresh tears from the eye’s surface. The upper sac wall moves back inward, pushing tears from the upper sac into the lower sac and duct. And the lower sac wall relaxes outward, generating suction that pulls tears further down the system. This two-phase cycle, close and open, repeats with every blink, roughly 15 to 20 times per minute, keeping the surface of your eye continuously refreshed.
What Happens When Tear Ducts Get Blocked
A blockage anywhere along the drainage path causes tears to back up and overflow onto the face, a condition called epiphora (chronic watery eyes). In some cases, stagnant fluid in the lacrimal sac becomes infected, leading to pain, swelling, and redness near the inner corner of the eye. The chronic form of this infection may cause only persistent watering without the more dramatic swelling.
Blockages happen for different reasons depending on age. In newborns, the nasolacrimal duct sometimes hasn’t fully opened by birth. This is remarkably common, affecting roughly 1 in 9 live births (about 11% of newborns). It’s typically diagnosed around 5 weeks of age and shows up as persistent tearing or a sticky discharge from one or both eyes. The good news is that most of these cases resolve on their own as the duct finishes developing in the first year.
In older adults, the puncta gradually narrow with age, making it harder for tears to enter the drainage system. Chronic inflammation, previous sinus infections, or even long-term use of certain eye drops can also contribute to narrowing or scarring of the duct.
Treating Blockages and Dry Eyes
When a blocked tear duct doesn’t resolve on its own, the most common surgical fix creates a new drainage route from the lacrimal sac directly into the nasal cavity, bypassing the blocked duct entirely. This can be done through a small incision on the side of the nose or entirely from inside the nose with an endoscope. Both approaches have high success rates: 85% to 99% for the external approach and 91% to 96% for the internal version.
Interestingly, the same drainage system that causes problems when blocked can also be intentionally plugged to treat the opposite issue: dry eyes. Tiny silicone plugs inserted into the puncta prevent tears from draining away, keeping more moisture on the eye’s surface. Studies show these plugs increase tear volume, stabilize the tear film, and reduce dry eye symptoms more effectively than artificial tears alone. Because plugs preserve the eye’s own natural tears rather than replacing them with drops, the effect lasts longer and provides more consistent relief.
Why Crying Makes Your Nose Run
This is one of those questions people rarely think to ask, but the answer is built into the anatomy. When you cry, the lacrimal glands produce far more fluid than the drainage system can handle at its normal pace. Tears spill over your eyelids and down your face. But a significant volume still makes it through the ducts into the nasal cavity, where it mixes with nasal mucus. The result is a runny nose that accompanies every good cry. It’s not a coincidence or a separate response. It’s the same fluid, arriving through the same plumbing.