• Allergies
• Blepharitis (a condition that causes eyelid inflammation)
• Chalazion or stye, which comes from inflammation in the glands of your eyelid
• Complication from a recent eye surgery
• Contact lens complication
• Corneal abrasion (scratch): First aid
• Corneal herpetic infection or herpes
• Corneal ulcer
• Dry eyes (caused by decreased production of tears)
• Ectropion (a condition in which the eyelid turns outward)
• Entropion (a condition in which the eyelid turns inward)
• Episcleritis, which is inflammation of the covering of the white part of the eye
• Eye drops side effect or complication
• Floppy eyelid syndrome, which happens when the eyelid can easily fold on itself
• Foreign object in the eye: First aid
• Glaucoma (which is a group of conditions that damage the optic nerve)
• Hay fever (also known as allergic rhinitis)
• Injury, such as from a blunt trauma or a burn
• Iritis (which is inflammation of the colored part of the eye)
• Keratitis (a condition involving inflammation of the cornea)
• Orbital cellulitis, which is an infection of the area around the eye
• Pink eye (conjunctivitis)
• Scleritis (which is inflammation of the white part of the eye)
• Subconjunctival hemorrhage (broken blood vessel in eye)

Seek immediate medical care if:

• Your eyesight changes suddenly.
• Red eye happens with a bad headache, eye pain, fever or if light starts to hurt your eyes.
• You also have an upset stomach or are throwing up.
• Red eye is caused by an object or chemical splashed in your eye.
• You suddenly begin to see circles around lights.
• You feel as if something is in your eye.
• You have swelling in or around your eye.
• You cannot open or keep your eye open.

Make an appointment with a health care provider

Sometimes, having red eye for a short time is not a reason to worry. If you think the redness is caused by an over-the-counter eye drop, try a different brand or take a break from using them.

Call your health care provider for an appointment if you have red eye that doesn't clear up after several days, especially if you have thick pus or mucous for a long time.

Contact your eye surgeon if:

• You're having eye redness with pain.
• You've had eye surgery or an eye injection in the past.