You won’t run out of tears the way you’d run out of water in a bottle. Your tear glands produce tears continuously in response to nerve signals, and there’s no fixed reservoir that empties. But prolonged crying can temporarily outpace your glands’ ability to keep up, leaving your eyes feeling dry, gritty, and strained. And certain medical conditions, medications, and even aging can reduce tear production enough that your eyes struggle to stay properly lubricated.
How Your Body Makes Tears
Your main tear-producing organ is the lacrimal gland, a small, tear-shaped gland tucked behind the upper outer corner of each eye. It’s made up mostly of serous acini, clusters of cells that secrete the watery component forming the bulk of your tear film. When your nervous system sends a signal (parasympathetic or sympathetic), specialized muscle cells wrapped around these clusters contract and squeeze the fluid out through tiny ducts onto the surface of your eye.
Because tear production is driven by nerve signals rather than drawn from a stored supply, your glands can keep manufacturing tears as long as they’re healthy and you’re reasonably hydrated. There’s no documented daily maximum. What does happen during a long cry is that production temporarily lags behind demand. Your eyes redden, your lids swell, and the tears become thinner and less effective at coating your eyes comfortably. Once you stop crying, the glands catch up within minutes.
Three Types of Tears, Three Different Jobs
Not all tears are the same. Your body produces three distinct types, each with a different chemical profile and purpose.
- Basal tears are the thin, constant film that keeps your cornea moist and nourished every moment of the day. You don’t notice them unless they stop working.
- Reflex tears flood the eye in response to irritants like onion vapors, dust, or wind. They’re more dilute than basal tears and packed with antimicrobial compounds like lysozyme to wash away threats and prevent infection.
- Emotional tears are unique to humans. They’re triggered by cognitive and emotional brain processes rather than physical irritation, and they contain higher protein concentrations. That extra protein makes them more viscous and sticky, which is why emotional tears cling to your skin and roll down your face slowly instead of sheeting off.
Recent metabolic research has found that even positive and negative emotional tears differ from each other. Negative emotional tears show metabolic signatures linked to inflammation and hormone regulation pathways, while positive emotional tears correlate with different metabolic processes entirely. Your brain is essentially producing a slightly different fluid depending on whether you’re crying from grief or joy.
When Tear Production Actually Drops
While a healthy person can’t truly “run out” of tears, several conditions can reduce production to the point where your eyes feel chronically dry.
Aging
Tear production declines steadily with age. Research measuring the thickness of the muco-aqueous layer of the tear film (the watery portion produced by the lacrimal gland) shows a clear downward trend. People in their twenties average about 4,009 nanometers of thickness, while those over 70 average just 2,819 nanometers, roughly a 30% reduction. This thinning is one reason dry eye becomes so common later in life.
Autoimmune Disease
Sjögren’s syndrome is the most well-known condition that directly attacks tear-producing glands. The immune system mistakenly targets the lacrimal glands (and salivary glands), gradually destroying their ability to produce moisture. People with Sjögren’s can reach a point where they produce almost no tears at all, which is the closest real-world scenario to “running out.”
Medications
Several common drug classes reduce tear volume as a side effect. Antihistamines, diuretics, and isotretinoin (used for severe acne) are among the most frequent culprits. If you’ve noticed your eyes feeling drier after starting a new medication, the drug itself may be suppressing your lacrimal gland output.
Dehydration
Your tear composition tracks your overall hydration surprisingly closely. In one controlled study, young adults who lost 2 to 3% of their body mass through exercise and water restriction saw their tear salt concentration rise in lockstep with their blood concentration. Essentially, when your body is low on water, your tears become saltier and less effective at protecting the eye surface. The good news: rehydration restored normal tear chemistry. Some researchers now recognize “systemic dehydration dry eye” as a distinct, reversible form of dry eye, separate from gland damage or other chronic causes.
How Doctors Measure Tear Production
If you’re concerned your eyes aren’t producing enough tears, the standard screening tool is the Schirmer test. A small strip of filter paper is hooked over your lower eyelid, and after five minutes your doctor measures how many millimeters of the strip are wet. Longer than 15 mm is normal. Between 10 and 15 mm suggests possible dry eye. Between 5 and 10 mm indicates moderate dryness, and anything under 5 mm points to severe tear deficiency.
The test is painless and takes only a few minutes. It won’t tell your doctor why production is low, but it confirms whether the glands are underperforming and helps guide next steps.
Why Your Eyes Feel Empty After a Long Cry
The sensation that you’ve “cried yourself out” is real, even though your glands haven’t actually emptied. After sustained emotional crying, several things happen at once. Your lacrimal glands are temporarily fatigued from producing a large volume of high-protein emotional tears. The tissues around your eyes are swollen from increased blood flow. Your nasal passages are congested because excess tears drain through ducts into your nose. And your body may be mildly dehydrated if you haven’t been drinking water.
The result is eyes that feel raw, tight, and dry, a stuffy nose, and a headache from the swelling and muscle tension. It feels like you’ve run out, but your glands are simply resting. Within an hour or so, basal tear production returns to normal and the discomfort fades. Drinking water and applying a cool cloth to your eyes can speed the recovery.