US Trends

what causes eyes to be red

Red eyes happen when the tiny blood vessels on the surface of your eye become swollen or dilated, making the whites look pink or bloodshot.

Main medical causes of red eyes

  • Allergies (like pollen, dust, pet dander) can inflame the clear tissue over the white of the eye (conjunctiva), leading to itchy, watery, red eyes.
  • Conjunctivitis (pink eye) – infection or irritation of the conjunctiva – makes the blood vessels swell so the eye looks pink or red, sometimes with discharge or a gritty feeling.
  • Dry eye syndrome leaves the surface of the eye unprotected, causing irritation, burning, and redness, especially after screens or in air‑conditioned rooms.
  • Contact lens problems (over‑wearing lenses, sleeping in them, poor cleaning) can irritate or infect the cornea and conjunctiva, causing redness, pain, and light sensitivity.
  • Injuries and foreign bodies (scratch, dust, chemical splash) directly damage the surface or deeper eye structures, which triggers redness and sometimes tearing or blurred vision.

Think of eye redness as your eye’s “check engine light” — it’s not a diagnosis itself, but a signal that something is irritating or inflaming the eye.

Less obvious but serious causes

Some causes are rarer but more urgent and should never be ignored:

  • Corneal ulcer or severe keratitis : an open sore or severe inflammation on the clear front surface of the eye, often from infection; usually brings intense pain, redness, light sensitivity, and sometimes a white spot on the cornea.
  • Uveitis / iritis : inflammation inside the eye (the colored part or deeper tissues) causing deep aching pain, light sensitivity, and blurred vision along with redness.
  • Glaucoma (acute angle‑closure) can present with a very red, very painful eye, halos around lights, headache, and nausea and is an emergency.
  • Orbital cellulitis or severe infection around the eye causes a red eye plus swollen, painful eyelids and sometimes fever and is also an emergency.

Everyday lifestyle and environmental triggers

Not all redness means disease; many day‑to‑day factors can set it off:

  • Lack of sleep or long screen time dries and strains the surface, making blood vessels more visible.
  • Smoke, fumes, chlorine, and dry air (planes, air‑con, windy environments) all irritate the eye and can cause temporary redness and burning.
  • Too much sun exposure without sunglasses can inflame the front surface (like a sunburn to the eye), leading to redness and soreness.
  • Overuse of “get the red out” drops : some decongestant eye drops temporarily shrink vessels but can cause rebound redness if used too often.

When red eyes are an emergency

You should seek urgent in‑person care (ER or same‑day eye doctor) if eye redness comes with:

  1. Sudden or severe eye pain.
  1. Sudden change in vision (blurry, dark curtain, halos).
  1. Sensitivity to light that makes it hard to open the eye.
  1. Significant trauma (hit in the eye, chemical splash, metal or glass in the eye).
  1. Fever, swollen eyelids, or the eye bulging forward.
  1. Recent eye surgery with new or worsening redness.

These situations can represent conditions that threaten sight and should not be managed at home.

Simple situations vs. see‑a‑doctor situations

For many people, mild redness that:

  • Affects both eyes
  • Feels more “scratchy” than painful
  • Improves with lubricating drops and rest

is often related to dryness or mild irritation.

But you should book a prompt eye‑care appointment if:

  • Redness lasts more than a few days.
  • There is thick discharge gluing the eyelids together.
  • You wear contact lenses and the eye becomes red, painful, or sensitive to light.
  • Redness keeps coming back with no clear trigger.

Information gathered from public forums or data available on the internet and portrayed here.