Excessive tearing, known clinically as epiphora, happens for one of two reasons: your eyes produce too many tears, or the tears you make can’t drain properly. Sometimes both problems occur at once. Understanding which mechanism is behind your watery eyes is the key to finding the right fix.
How Tears Normally Work
Your tear film has three layers: an outer oily layer, a watery middle layer, and an inner mucus layer. The oily layer, produced by tiny glands along your eyelid margins called meibomian glands, keeps tears from evaporating too quickly. The watery layer comes from the lacrimal gland above each eye. And the mucus layer helps tears stick evenly to the eye’s surface.
After tears coat the eye, they drain through two small openings (puncta) in the inner corners of your upper and lower eyelids, travel through narrow channels called canaliculi, and empty into the nasolacrimal duct, which leads into your nose. That’s why your nose runs when you cry. When anything disrupts either the production side or the drainage side of this system, tears overflow onto your cheeks.
Dry Eyes: The Most Counterintuitive Cause
It sounds backwards, but dry eye syndrome is one of the most common reasons for watery eyes. When your tear film breaks down too quickly or doesn’t coat the eye evenly, the exposed surface becomes irritated. Your nervous system detects that irritation and triggers the lacrimal gland to flood the eye with emergency “reflex” tears. All tear production is initiated by some form of stimulus, and a dry, unstable tear film provides constant stimulus.
These reflex tears are mostly water. They lack the balanced oil and mucus of a healthy tear film, so they don’t stick around or protect the surface effectively. The cycle repeats: the eye dries out again, triggers another wave of watery tears, and the overflow continues. This is why many people with chronically watery eyes are actually told they have dry eye disease.
Meibomian Gland Dysfunction
The meibomian glands produce the oily outer layer of your tears. When these glands become clogged or stop secreting enough quality oil, the tear film loses its protective seal and evaporates too fast. This condition, called meibomian gland dysfunction (MGD), is one of the leading contributors to dry eye and, by extension, to reflex tearing.
In the most common form, obstructive MGD, the glands fill up with thickened oil that can’t flow out. Over time, untreated MGD can lead to eyelid inflammation (blepharitis), eye surface disease, and persistent watering. Symptoms often include gritty-feeling eyes, redness, and, paradoxically, eyes that water frequently.
Blocked Tear Ducts
If your tear drainage pathway is narrowed or blocked, tears have nowhere to go and pool on the eye surface until they spill over. In adults, the three main causes of a blocked nasolacrimal duct are infection, injury, and tumors.
- Chronic infection or inflammation. Long-standing infections of the eyes, tear drainage system, or nose can cause the duct lining to swell and scar shut over time.
- Facial injury. Trauma to the face, particularly around the nose and cheekbones, can damage the bone or soft tissue near the drainage pathway and disrupt normal tear flow.
- Tumors. Rarely, a growth in the nose or anywhere along the tear drainage system presses on the duct and causes a blockage.
In infants, blocked tear ducts are extremely common. A thin membrane at the bottom of the nasolacrimal duct sometimes hasn’t opened at birth. The good news: roughly 90% to 96% of these cases resolve on their own within the first year of life with nothing more than observation and gentle massage of the inner corner of the eye.
Eyelid Malpositions
Your eyelids need to close fully and sit snugly against the eye for tears to spread evenly and reach the drainage openings. Two conditions interfere with this.
In ectropion, the lower eyelid turns outward, pulling away from the eye. The upper and lower lids can no longer meet properly, so tears aren’t spread across the surface and can’t reach the puncta to drain. In entropion, the eyelid turns inward, pushing the lashes against the eye. Both conditions cause irritation, a foreign-body sensation, redness, and watering. Ectropion causes tearing primarily because drainage is disrupted, while entropion causes tearing primarily because the lashes constantly irritate the cornea and trigger reflex tear production.
These eyelid changes are most common in older adults as the tissues supporting the eyelid loosen with age, but they can also follow scarring from injury, infection, or surgery.
Misdirected Eyelashes
Even when the eyelid itself sits in the correct position, individual lashes can grow inward toward the eye. This condition, called trichiasis, causes the misdirected lashes to scrape against the cornea and the delicate tissue covering the white of the eye. The constant friction irritates the surface, and the eye responds with persistent tearing. Left untreated, these rogue lashes can cause corneal scratches and, in severe cases, corneal ulcers.
Corneal Scratches and Foreign Bodies
Anything that damages or irritates the cornea triggers an intense reflex tearing response. A scratch from a contact lens, a speck of dust or metal, a splash of chemical irritant, or even a strong gust of wind can cause your eyes to water heavily. This is your body’s defense mechanism: flooding the surface to wash away the threat and keep the cornea moist while it heals. Most minor corneal abrasions heal within a day or two, and the tearing subsides once the surface is intact again.
Allergies, Infections, and Inflammation
Allergic conjunctivitis, commonly triggered by pollen, pet dander, or dust mites, causes itching, redness, and watery eyes. The watering is a reflex response to the inflammatory chemicals released on the eye’s surface. Viral and bacterial conjunctivitis (pink eye) also produce tearing, though the discharge tends to be thicker and may be yellowish or greenish with bacterial infections.
Blepharitis, or inflammation along the eyelid margins, disrupts the glands and structures at the base of the lashes. It often overlaps with meibomian gland dysfunction and creates a chronic cycle of irritation, poor tear quality, and overflow tearing.
Medications That Cause Tearing
Certain medications can trigger excessive tearing through different pathways. Some eye drops, particularly older glaucoma medications, can cause the puncta and drainage channels to narrow and scar over time, physically blocking tear outflow. Others stimulate the lacrimal gland directly. Drugs that activate the same nerve pathways your body uses to trigger crying (cholinergic pathways) can cause inappropriate tear production even when there’s nothing wrong with the eye itself. If your tearing started after beginning a new medication, that connection is worth discussing with whoever prescribed it.
Environmental Triggers
Wind, cold air, bright sunlight, smoke, and strong fumes are all common triggers for reflex tearing. These don’t indicate an underlying problem. They’re normal protective responses. However, if your eyes water excessively in conditions that don’t bother most people, it often points to an underlying tear film instability (like mild dry eye or MGD) that lowers your threshold for reflex tearing.
Screen use is another subtle trigger. When you concentrate on a screen, your blink rate drops significantly. Fewer blinks means the tear film breaks down faster between blinks, and the resulting dryness can kick off a reflex tearing episode, especially later in the day.
How the Cause Is Identified
An eye care provider typically starts by examining the eyelids, lashes, and eye surface under magnification to check for inflammation, misdirected lashes, or eyelid malposition. They’ll look at your tear film to assess whether it’s breaking down too quickly.
If a drainage blockage is suspected, one straightforward test involves placing a drop of fluorescein dye in each eye and checking after five minutes. Normally, most of the dye clears through the drainage system. If the dye pools on the eye surface, drains unevenly between the two eyes, or overflows down the cheek, that points to a blocked or narrowed drainage pathway. Further testing can pinpoint exactly where the blockage sits by flushing saline through the drainage system and checking whether it reaches the nose.
In most cases, the cause of excessive tearing is identifiable and treatable. The fix depends entirely on whether the problem is overproduction, poor drainage, or both, which is why getting the right diagnosis matters more than reaching for eye drops on your own.