Red Eye: Causes, When to Worry, and Treatment

Red eye happens when blood vessels on the white part of your eye become swollen. It's usually caused by minor issues like allergies, dryness, or mild infections, but can sometimes indicate serious eye problems. See a doctor if you have pain, vision changes, or the redness lasts more than a few days.

In plain words

Red eye happens when blood vessels in your eye swell up, making the eye look red. It can be caused by many things like allergies, dryness, or minor infections. Most of the time, it’s not serious and gets better on its own. But sometimes, it can be a sign of a bigger problem like an infection or glaucoma. If you have pain, vision changes, or redness that won’t go away, see a doctor.

What is Red Eye: Causes, When to Worry, and Treatment?

Symptoms

Early symptoms

Mild eye irritation: Your eye may feel slightly scratchy or uncomfortable, without severe pain. The whites of the eye appear pink or red. (1) (6)
Increased tearing: Your eye may water more than usual as it responds to irritation or dryness. (1)
Slight light sensitivity: You might squint more in bright light than usual, though vision remains clear. (2)
Mild discharge or crusting: You may notice some clear or white discharge, especially in the morning, if conjunctivitis is developing. (4)

Serious or emergency symptoms

Severe eye pain: Intense pain that doesn't improve with over-the-counter pain relievers, especially if accompanied by nausea or vomiting. Seek emergency care immediately as this could indicate acute glaucoma. (5)
Sudden vision changes: Blurry vision, double vision, or loss of vision that comes on suddenly requires urgent medical evaluation. Go to an emergency room or call your eye doctor immediately. (5)

Causes

Primary causes

Conjunctivitis (pink eye): Inflammation of the clear membrane covering the white part of your eye, caused by viruses, bacteria, or allergies. Viral conjunctivitis is most common and very contagious. (1) (4)
Dry eye syndrome: When your eyes don't produce enough quality tears, leading to irritation and redness that often worsens in dry or windy conditions. (2) (6)
Allergies: Pollen, pet dander, or dust can trigger an allergic reaction in the eyes, causing itching, watering, and redness that often affects both eyes. (1) (2)
Eye strain: Prolonged screen use or focusing on close work without breaks can lead to tired, red eyes that feel better with rest. (2)

Contributing factors

Acute glaucoma: A sudden increase in eye pressure that damages the optic nerve, causing severe pain, nausea, and vision changes. This is a medical emergency. (5)
Corneal ulcers: Open sores on the cornea (clear front of the eye) often caused by infection and requiring prompt antibiotic treatment to prevent vision loss. (5)
Uveitis: Inflammation of the middle layer of the eye that can cause pain, light sensitivity, and floaters in your vision. (5)

Risk factors

Wearing contact lenses

Contacts can irritate eyes and increase infection risk, especially if worn too long or not cleaned properly. (1)

Dry environments

Living or working in air-conditioned spaces, airplanes, or dry climates makes dry eye and redness more likely. (2)

Allergies

People with seasonal or environmental allergies are prone to allergic conjunctivitis. (1)

Prolonged screen use

Staring at digital devices reduces blinking and can lead to tired, irritated eyes. (2)

Diagnosis

Your doctor will examine your eyes and ask about your symptoms, how long they've lasted, and if anything makes them better or worse. They may check your vision, use a special microscope to look closely at your eye's surface, and sometimes use eye drops that help highlight damage or measure eye pressure. The examination is usually not painful and helps determine if your red eye needs treatment or will improve on its own.

Visual acuity test

Standard eye chart test to check if your vision has changed due to the redness. (2)

Slit-lamp examination

Special microscope that gives your doctor a magnified view of eye structures to look for signs of infection or injury. (2)

Fluorescein staining

Orange dye and blue light that reveals scratches or ulcers on the cornea that might be causing redness. (2)

Tonometry

Painless test to measure eye pressure, important if glaucoma is suspected. (5)

Treatment

Medication options

Antibiotic eye drops or ointments

These treat bacterial infections that cause pink eye or other bacterial eye infections. They don't help with viral infections. (3) (7)

Antihistamine eye drops

Relieves itching and redness caused by eye allergies. Some newer formulas can be used once daily. (3) (4)

Artificial tears

Lubricates dry eyes and washes away irritants. Preservative-free options are best for frequent use. (3) (7)

Lifestyle and self-care

Cool compresses: Apply a clean, damp, cool cloth to closed eyelids for 5-10 minutes to soothe irritation and reduce swelling. (3) (7)
Protective eyewear: Wear sunglasses outdoors to shield eyes from wind and sun, and goggles when swimming to avoid chlorine irritation. (3)
Screen breaks: Follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds to reduce eye strain. (3)
Proper contact lens care: Always follow lens cleaning instructions, never sleep in daily wear contacts, and replace lenses as recommended. (7)

Always discuss dosing and treatment changes with your own prescriber.

Possible complications

Corneal damage: Severe or untreated eye infections can scar the clear front surface of the eye, potentially affecting vision. (5)
Spread of infection: Viral and bacterial pink eye are both highly contagious without proper hygiene, potentially affecting household members. (4)
Vision loss: Conditions like acute glaucoma or untreated uveitis can cause permanent vision damage if not treated promptly. (5)

When to see a doctor

Routine follow-up

Schedule a doctor visit if redness lasts more than a few days, gets worse with home care, or comes with mild discomfort or discharge. (1)
See your doctor if you develop red eye while wearing contact lenses, as this increases infection risk. (5)

Seek emergency care

Seek immediate medical care for sudden vision changes, severe pain, intense light sensitivity, or redness after eye trauma. (5)
Get emergency help if red eye is accompanied by nausea, vomiting, or seeing halos around lights — possible signs of acute glaucoma. (5)

Frequently asked questions

What causes red eye?

Common causes include allergies, dry eyes, infections like conjunctivitis, eye strain, and irritants like smoke or chlorine. More serious causes include glaucoma, uveitis, or corneal ulcers. Most cases aren't serious, but some require medical attention. (1) (4)

When should I worry about red eye?

Contact a doctor right away if you have severe pain, vision changes, or the redness follows an injury. Also seek care if redness lasts more than a few days or comes with thick discharge. Emergency symptoms include nausea, seeing halos, or extreme light sensitivity. (5)

How do I get rid of red eye?

Treatment depends on the cause. Allergies may improve with antihistamine drops, infections may need antibiotic drops, and artificial tears help dry eyes. Cool compresses can soothe irritation. Always consult a doctor if symptoms persist or worsen. (3) (7)

Is red eye serious?

Most often, no — but sometimes it can signal serious conditions like acute glaucoma or eye infections that threaten vision. Pain, vision changes, and light sensitivity are red flags that need prompt medical evaluation. (5)

Can red eye be prevented?

You can reduce risk by washing hands often, not rubbing eyes, properly cleaning contact lenses, taking screen breaks, wearing protective eyewear, and managing allergies. See your doctor for ongoing dry eye or allergy symptoms. (3) (7)

References

NHS — Red eye source 1
Mayo Clinic — Red eye causes source 2
Cleveland Clinic — Red Eye Treatment source 3
MedlinePlus — Conjunctivitis source 4
Mayo Clinic — When to see a doctor for red eye source 5
MedlinePlus — Red Eye source 6
NHS — Red eye treatment source 7