Pink eye, medically known as conjunctivitis, is a common condition involving the inflammation of the conjunctiva. This thin, transparent membrane covers the white part of the eyeball and lines the inner surface of the eyelids. When the small blood vessels within this membrane become inflamed, they become more visible, causing the eye to appear reddish or pink. While highly transmissible, pink eye is rarely a serious health concern and typically resolves without long-term issues.
Symptom Onset Timelines Based on Cause
The speed at which pink eye symptoms appear after exposure depends on the underlying cause: viral, bacterial, or allergic. Viral conjunctivitis, the most frequent cause, often has an incubation period ranging from one to three days after initial contact, though symptoms can take up to twelve days to fully manifest. This form is frequently caused by adenoviruses, which are also responsible for many common cold symptoms.
Bacterial conjunctivitis has a much shorter onset time. Symptoms usually begin to appear within 24 to 72 hours after exposure to bacteria like Staphylococcus aureus or Streptococcus pneumoniae. These bacteria can spread quickly through contaminated hands or shared items.
Allergic conjunctivitis is not an infection and has no incubation period. This type occurs instantaneously or within minutes to hours of exposure to an environmental trigger, such as pollen, pet dander, or dust. The reaction is a direct immune response to the allergen, causing a rapid onset of irritation.
Recognizing the First Signs of Infection
The initial indications of pink eye are often subtle, starting with a gritty or sandy sensation in the eye. This is quickly followed by mild redness on the white part of the eye, increased tearing, and a slight itching or burning sensation.
As the condition progresses, a discharge appears, the nature of which can hint at the cause. Viral infections typically produce a watery or clear discharge. Bacterial infections often result in a thicker, pus-like discharge that is yellow, white, or greenish. This thicker discharge can cause the eyelids to stick together, particularly upon waking in the morning.
How Long Pink Eye Remains Contagious
Only infectious forms of pink eye (viral and bacterial) pose a risk of transmission. Viral pink eye is typically contagious for as long as symptoms are present, often spanning 10 to 14 days from the onset. Some viruses, like adenovirus, can continue to shed for up to two weeks, and the most transmissible period is generally the first three to five days after symptoms begin.
Bacterial conjunctivitis remains contagious until the symptoms resolve, which can take about a week without intervention. If antibiotic eye drops are prescribed, the contagious period is significantly shortened. A person is generally considered non-contagious 24 hours after starting treatment.
Allergic conjunctivitis is not infectious and cannot be spread from person to person. The symptoms will persist only as long as the eyes are exposed to the triggering substance.
Knowing When to Seek Medical Care
While many cases of pink eye are mild and resolve on their own, certain symptoms suggest the need for a professional medical evaluation. You should seek care if you experience severe pain in the eye or rapidly worsening redness and irritation. A significant increase in sensitivity to light, known as photophobia, is another sign that requires prompt attention.
Any change in vision, such as blurriness that does not clear with blinking, should prompt a doctor’s visit. Individuals who wear contact lenses must stop wearing them immediately and seek professional advice if pink eye symptoms appear, as they are at a higher risk for more severe eye infections. Medical care is also necessary if symptoms do not begin to improve after several days of self-care.