Watery eyes, known medically as lacrimation or epiphora, is a very common symptom many parents notice when their child is sick. Tears clean and lubricate the eye, but during illness, this clear fluid can overflow constantly. This observation is rarely a sign of a serious problem and is often simply a side effect of the body’s immune response to a common cold or other respiratory infection. Understanding the connection between a runny nose and watery eyes involves looking closely at the delicate plumbing system that connects the eyes and the nasal passages.
How Illness Triggers Excess Tearing
The excessive tearing seen during an illness is typically caused by a combination of two distinct physiological events: overproduction of tears and impaired drainage of those tears. When the body detects a virus or allergen, it initiates an inflammatory response, which involves releasing compounds like histamine. This inflammatory action can directly irritate the eye’s surface, triggering the lacrimal glands to increase tear production in an effort to wash away the irritant.
The more common reason for overflow, however, is a temporary blockage in the drainage system. Tears usually drain through tiny openings called puncta, located in the inner corner of the eyelids, into the nasolacrimal ducts, and finally into the nose. When a child has a cold or flu, the mucous membranes lining the nasal passages and the tear ducts become swollen and inflamed. This swelling constricts the nasolacrimal duct, essentially clogging the drainpipe that carries tears away.
Because the tears cannot drain properly into the congested nose, they accumulate on the eye’s surface and spill over onto the cheek. Impaired drainage is why eyes appear wetter when lying down, as gravity no longer assists drainage.
Identifying the Most Common Causes
The most frequent culprit behind watery eyes in a sick child is a Viral Upper Respiratory Infection (URI), commonly known as a cold. Viruses like rhinovirus or adenovirus cause widespread inflammation in the upper respiratory tract, simultaneously increasing tear production and clogging the drainage paths. In some cases, an infection like adenovirus can cause viral conjunctivitis, or pink eye, which results in significant watery discharge and a reddish appearance. This type of watery eye is generally self-limiting and resolves as the viral illness passes.
Allergies, particularly allergic conjunctivitis, are another major contributor and frequently overlap with cold symptoms. The body’s reaction to environmental triggers like pollen or pet dander involves the release of histamine. Histamine causes small blood vessels in the conjunctiva to dilate and become leaky, leading to redness, itching, and an intense spike in tear production. Although not an infectious illness, allergic tearing—which includes clear, excessive, and sometimes itchy discharge—is often confused with a cold.
Illness can also make the eyes more sensitive to Environmental Factors and Irritants. When a child is already fighting a virus, the mucosal surfaces of the eyes are often more vulnerable to external factors. Exposure to dry air, wind, dust, or smoke can cause reflex tearing as the eye attempts to protect its already irritated surface.
Warning Signs and When to Consult a Doctor
While most watery eyes during illness are harmless, parents should monitor for specific red flags that may indicate a more serious condition requiring medical attention. A significant change in the nature of the discharge is a primary warning sign. If the tears are no longer clear and watery, but instead become thick, yellow, or greenish, this may suggest a bacterial infection like bacterial conjunctivitis. This discharge can cause the eyelids to stick together, especially after waking up.
Severe symptoms, such as intense eye pain, a noticeable change in vision, or extreme light sensitivity, known as photophobia, warrant immediate consultation with a healthcare provider. These signs may point toward inflammation of the cornea or a deeper, more serious eye infection.
Another serious, though rare, complication is dacryocystitis, which is a bacterial infection of the lacrimal sac that presents as a painful, red, and swollen bump near the inner corner of the eye. It is also important to seek professional advice if the watery eyes persist long after the primary symptoms of the cold have disappeared. Tearing that continues for weeks could suggest a persistent nasolacrimal duct obstruction or the presence of a foreign body in the eye.