Red Eye: Causes, Symptoms & When to Seek Care

What Causes Red Eyes?

Red eyes occur when the small blood vessels on the surface of the eye (in the conjunctiva and sclera) become dilated and more visible. This happens due to irritation, infection, allergies, dryness, eye strain, or occasionally more serious conditions like acute glaucoma or iritis. Most causes are benign and self-limiting.

Red eyes are one of the most common eye complaints that lead people to seek medical care. The redness you see is caused by dilated blood vessels in the conjunctiva, the thin, transparent membrane that covers the white part of the eye (sclera) and lines the inside of the eyelids. When these blood vessels expand due to irritation or inflammation, they become more visible, giving the eye a red or bloodshot appearance.

Understanding what's causing your red eyes is important because treatment varies significantly depending on the underlying condition. While most cases of red eye are caused by minor, self-limiting conditions that resolve on their own, some causes require prompt medical attention to prevent complications, including permanent vision loss.

The eye is a delicate and complex organ, and the conjunctiva serves as one of its first lines of defense against pathogens and irritants. When this membrane detects a threat or irritation, it triggers an inflammatory response that increases blood flow to the area, resulting in the characteristic redness. This is actually a protective mechanism, but it can be uncomfortable and concerning when it occurs.

Common Causes of Red Eyes

Red eyes can be caused by many different factors, ranging from environmental irritants to infections and systemic conditions. Understanding these causes can help you determine when home treatment is appropriate and when you should seek professional medical care.

• Conjunctivitis (Pink Eye): The most common cause, which can be viral, bacterial, or allergic in origin
• Dry Eye Syndrome: Insufficient tear production or poor tear quality leads to irritation and redness
• Allergies: Seasonal or perennial allergens trigger histamine release, causing itching and redness
• Eye Strain: Prolonged screen use, reading, or driving can cause fatigue and redness
• Contact Lens Problems: Overwearing, poor hygiene, or lens reactions can irritate the eye
• Foreign Body: Dust, sand, or other particles trapped under the eyelid
• Subconjunctival Hemorrhage: A burst blood vessel causing a bright red patch on the white of the eye
• Blepharitis: Inflammation of the eyelid margins, often associated with clogged oil glands
• Stye (Hordeolum): A bacterial infection of an oil gland in the eyelid
• Environmental Irritants: Smoke, pollution, chlorine from swimming pools, or dry air

Less Common But Serious Causes

While most red eyes are caused by benign conditions, certain serious eye problems also present with redness. These conditions require immediate medical attention to prevent permanent damage to your vision. Recognizing the warning signs of these conditions is crucial for your eye health.

Acute angle-closure glaucoma is one of the most urgent causes of red eye. This condition occurs when the drainage angle in the eye becomes suddenly blocked, causing a rapid increase in eye pressure. Symptoms include severe eye pain, headache, nausea, vomiting, halos around lights, and decreased vision. This is a medical emergency requiring immediate treatment to prevent permanent vision loss.

Iritis (anterior uveitis) is an inflammation of the iris, the colored part of the eye. It causes deep, aching pain, sensitivity to light, blurred vision, and a smaller pupil in the affected eye. Without treatment, iritis can lead to complications including glaucoma and vision loss.

Keratitis is an infection or inflammation of the cornea, the clear dome at the front of the eye. It's particularly common in contact lens wearers and can be caused by bacteria, viruses, fungi, or parasites. Symptoms include severe pain, excessive tearing, light sensitivity, and decreased vision. Untreated keratitis can cause corneal scarring and permanent vision impairment.

What Are the Symptoms of Red Eyes?

Symptoms accompanying red eyes depend on the underlying cause. Common symptoms include itching, burning, watery eyes, discharge, gritty sensation, swollen eyelids, and light sensitivity. Pain, vision changes, and severe light sensitivity suggest more serious conditions requiring immediate medical attention.

Red eyes rarely occur in isolation. The accompanying symptoms provide important clues about the underlying cause and help determine whether you need to seek medical care. Paying attention to these additional symptoms can help you and your healthcare provider identify the problem more quickly and start appropriate treatment.

The pattern of symptoms is particularly helpful in distinguishing between different causes. For example, allergic conjunctivitis typically causes intense itching in both eyes, while bacterial conjunctivitis usually produces thick, yellowish discharge. Understanding these patterns can help you make informed decisions about your care.

Symptoms Indicating Mild Conditions

Many symptoms of red eye suggest relatively mild conditions that often resolve without medical treatment. These include mild itching, a gritty or sandy sensation, slight discomfort without actual pain, watery discharge, and mild swelling of the eyelids. The redness is typically diffuse across the white of the eye rather than concentrated in one area.

With mild conditions, your vision should remain clear or only slightly blurred due to excess tears or discharge. The symptoms are often bilateral (affecting both eyes), especially with allergies, and may come and go or vary in intensity throughout the day. These conditions usually improve within a few days with simple home care measures.

Warning Signs Requiring Immediate Medical Attention

Certain symptoms accompanying red eye indicate potentially serious conditions that require prompt medical evaluation. Recognizing these warning signs is essential for protecting your vision and overall eye health.

• Severe eye pain: Pain that goes beyond mild discomfort, especially if it's deep or throbbing
• Sudden vision changes: Blurred vision, partial vision loss, or seeing halos around lights
• Extreme light sensitivity: Photophobia that makes it difficult to open your eyes in normal light
• Nausea and vomiting: Especially when combined with eye pain and redness
• Eye trauma: Any recent injury to the eye or exposure to chemicals
• Unequal pupil sizes: One pupil larger or smaller than the other
• Fever: Especially in newborns and infants with eye redness
• Contact lens wearer with pain: Could indicate corneal infection requiring urgent treatment

When Should You See a Doctor for Red Eyes?

Most red eyes don't require medical care and resolve within 5-7 days. See a doctor if symptoms persist beyond one week, if you have pain or vision changes, if discharge is thick and yellow/green, if you wear contact lenses and develop symptoms, or if you have a weakened immune system.

Knowing when to seek medical attention for red eyes can be confusing, as most cases are harmless while others require urgent care. The key is to pay attention to the specific symptoms you're experiencing and how they're progressing. In general, symptoms that are getting worse rather than better, or that are accompanied by pain or vision changes, warrant medical evaluation.

For most adults with mild red eye symptoms and no concerning features, it's reasonable to try home remedies for 3-5 days before seeking medical care. However, children, contact lens wearers, and people with weakened immune systems should have a lower threshold for seeing a doctor, as complications can develop more quickly in these groups.

Situations Requiring Same-Day Medical Care

Certain situations warrant prompt medical attention, ideally within the same day or within 24-48 hours. These include moderate to severe pain, significant vision changes, a history of recent eye surgery, wearing contact lenses with developing symptoms, or a known condition like herpes simplex that can affect the eye.

If you've been exposed to someone with confirmed bacterial conjunctivitis and you develop symptoms, especially with thick discharge, seeing a doctor sooner rather than later can help you get appropriate antibiotic treatment and reduce your contagious period.

When Home Care Is Appropriate

Home care is appropriate for most cases of mild red eye without concerning symptoms. This includes situations where you have mild redness without significant pain, your vision is normal, the discharge is watery rather than thick and colored, and you've been exposed to obvious triggers like allergens, smoke, or prolonged screen use.

If you choose home care, monitor your symptoms carefully. If they're not improving after 5 days of self-care, or if they begin to worsen at any point, it's time to see a healthcare provider. Keep track of any changes so you can provide accurate information to your doctor.

What Are the Different Types of Red Eye Conditions?

Red eye conditions include conjunctivitis (viral, bacterial, or allergic), blepharitis, styes, subconjunctival hemorrhage, dry eye syndrome, keratitis, iritis, and acute glaucoma. Each has distinct characteristics and treatment approaches, ranging from self-care to emergency intervention.

Conjunctivitis (Pink Eye)

Conjunctivitis is the most common cause of red eye and refers to inflammation of the conjunctiva. It can be caused by viruses, bacteria, or allergies, and the treatment depends on the underlying cause. Understanding which type you have is important for appropriate management.

Viral conjunctivitis is typically caused by adenovirus and often accompanies or follows a cold or upper respiratory infection. It usually starts in one eye and may spread to the other within a few days. The discharge is typically watery and clear. There's no specific treatment; it resolves on its own within 7-14 days. Viral conjunctivitis is highly contagious for 10-14 days.

Bacterial conjunctivitis produces thick, yellow or greenish discharge that may cause the eyelids to stick together, especially upon waking. It can affect one or both eyes and may be treated with antibiotic eye drops, which can shorten the course of illness and reduce contagiousness. Without treatment, most cases still resolve within 7-10 days.

Allergic conjunctivitis occurs when allergens like pollen, dust mites, or pet dander trigger an immune response in the eyes. Both eyes are typically affected, and intense itching is the hallmark symptom. The eyes may also water excessively. This condition is not contagious and can be managed with antihistamine drops and allergen avoidance.

Stye (Hordeolum)

A stye is a painful, red bump that develops when a gland at the edge of the eyelid becomes infected, usually by Staphylococcus bacteria. Styes resemble pimples and may form on the outer or inner eyelid. Most styes come to a head and drain on their own within a week, though they can be quite uncomfortable during this time.

Treatment involves applying warm compresses several times daily to encourage drainage. Most styes don't require antibiotics, but if a stye doesn't improve after a week or if the redness spreads, medical evaluation is recommended. Never attempt to squeeze or pop a stye, as this can spread the infection.

Blepharitis

Blepharitis is a chronic inflammation of the eyelid margins that causes redness, itching, and a gritty sensation. It often occurs alongside dry eye syndrome and is commonly associated with skin conditions like seborrheic dermatitis or rosacea. The condition tends to wax and wane over time.

Management focuses on good eyelid hygiene, including daily warm compresses and gentle lid scrubs to remove crusts and debris from the eyelash base. Many people need to continue these practices long-term to keep symptoms under control. In some cases, antibiotic ointments or oral antibiotics may be prescribed.

Subconjunctival Hemorrhage

A subconjunctival hemorrhage occurs when a small blood vessel breaks underneath the conjunctiva, causing a bright red patch on the white of the eye. Despite its alarming appearance, this condition is usually harmless and painless. The blood is trapped between the conjunctiva and sclera and cannot be wiped away.

The cause is often unclear, but it can follow coughing, sneezing, straining, or minor trauma. No treatment is needed; the blood is gradually absorbed over 1-3 weeks in adults and about 1 week in children. If you experience repeated subconjunctival hemorrhages, see a doctor to check for underlying blood pressure or clotting issues.

Dry Eye Syndrome

Dry eye syndrome occurs when the eyes don't produce enough tears or when tears evaporate too quickly. This leads to chronic irritation, redness, and a scratchy or burning sensation. Risk factors include aging, certain medications, autoimmune conditions, and prolonged screen use, which reduces blinking frequency.

Management includes artificial tears, lifestyle modifications (taking screen breaks, using humidifiers), and addressing underlying causes. In more severe cases, prescription medications, punctal plugs, or other interventions may be recommended by an eye care specialist.

How Can You Treat Red Eyes at Home?

Home treatment for red eyes includes artificial tears for lubrication, cold compresses for allergic reactions, warm compresses for styes and blepharitis, removing contact lenses, avoiding eye rubbing, taking screen breaks, and staying hydrated. Over-the-counter antihistamine drops help allergic symptoms.

Many cases of red eye can be effectively managed at home with simple, conservative measures. The key is to address the underlying cause when possible while providing comfort and supporting your eye's natural healing processes. Home care is appropriate for mild symptoms without warning signs of serious conditions.

Before starting any home treatment, make sure you've ruled out conditions requiring medical care. If you're unsure about the cause of your red eye, it's better to err on the side of caution and consult a healthcare provider, especially if symptoms are severe or worsening.

Artificial Tears and Lubricating Drops

Artificial tears are one of the most versatile and effective treatments for red eyes. They help wash away irritants, provide lubrication for dry eyes, and soothe general irritation. Use preservative-free artificial tears if you need to apply drops more than 4 times daily, as preservatives can cause irritation with frequent use.

Apply 1-2 drops as needed throughout the day. If you're treating dry eyes, regular use (every few hours while awake) is more effective than waiting until symptoms become severe. Store drops properly and discard them after the recommended time period to prevent contamination.

Warm and Cold Compresses

Compresses are a simple but effective treatment for many causes of red eye. The type of compress you use depends on the underlying condition, so choosing the right one is important for optimal results.

Warm compresses are ideal for styes, blepharitis, and blocked oil glands (meibomian gland dysfunction). The warmth helps soften oily secretions and promotes drainage. Soak a clean washcloth in warm (not hot) water, wring it out, and apply to closed eyelids for 5-10 minutes, 2-4 times daily. Re-warm the cloth as needed to maintain consistent temperature.

Cold compresses are better for allergic reactions and general irritation. The cold helps reduce swelling and provides immediate soothing relief. Use a clean cloth dampened with cold water, or wrap ice in a cloth. Apply for 10-15 minutes as needed, taking care not to apply ice directly to the skin.

Contact Lens Care

If you wear contact lenses and develop red eyes, remove your lenses immediately and switch to glasses until symptoms fully resolve. Contact lenses can trap irritants against the eye and prevent healing. Additionally, lenses worn during an eye infection may harbor pathogens and should not be reused.

After an eye infection or significant irritation, start with a fresh pair of lenses and a new lens case. Review your lens care routine to ensure you're following proper hygiene practices, including regular case replacement, using fresh solution daily, and not overwearing your lenses.

The 20-20-20 Rule for Eye Strain

Digital eye strain is an increasingly common cause of red, tired eyes. The 20-20-20 rule is a simple technique to reduce this strain: every 20 minutes, look at something 20 feet away for 20 seconds. This gives your focusing muscles a break and encourages blinking, which lubricates the eyes.

Additionally, position your screen about arm's length away and slightly below eye level. Adjust screen brightness to match your surroundings, and consider using blue light filtering if you work at screens for extended periods. Taking regular breaks to stand, stretch, and look away from screens also helps.

How Can You Prevent Red Eyes?

Prevent red eyes by practicing good hand hygiene, not touching or rubbing your eyes, properly caring for contact lenses, protecting eyes from irritants and allergens, taking regular screen breaks, staying hydrated, and managing underlying conditions like allergies or dry eye syndrome.

While not all causes of red eye can be prevented, many common triggers can be avoided with simple lifestyle modifications and good hygiene practices. Prevention is particularly important for people who experience recurrent red eye episodes or who are at higher risk for eye infections.

The eyes are a common entry point for pathogens, and many eye infections are transmitted through hand-to-eye contact. Making conscious efforts to keep your hands clean and away from your eyes can significantly reduce your risk of developing infectious conjunctivitis and other eye problems.

Hand Hygiene and Avoiding Eye Touching

Washing your hands regularly is one of the most effective ways to prevent eye infections. Use soap and water for at least 20 seconds, or use alcohol-based hand sanitizer when soap isn't available. Pay particular attention to hand washing before touching your face or eyes, after using the bathroom, after contact with sick individuals, and before handling contact lenses.

Try to break the habit of rubbing or touching your eyes. This is easier said than done, as many people touch their eyes unconsciously throughout the day. Being aware of this habit is the first step to changing it. If your eyes itch, use artificial tears instead of rubbing.

Contact Lens Hygiene

Proper contact lens care is essential for preventing eye infections and irritation. Follow these evidence-based practices to keep your eyes healthy while wearing contacts:

• Never sleep in daily wear lenses: Overnight wear dramatically increases infection risk
• Replace lenses on schedule: Don't extend wear beyond recommended replacement dates
• Use fresh solution daily: Never top off old solution or reuse solution
• Clean and replace cases regularly: Replace lens cases at least every 3 months
• Don't swim or shower in contacts: Water exposure increases risk of serious infections
• Handle lenses with clean, dry hands: Wash and dry hands before touching lenses
• Remove lenses if eyes become red or irritated: Don't push through discomfort

Environmental and Lifestyle Factors

Your environment and daily habits significantly impact eye health. Take steps to protect your eyes from common irritants and create conditions that support healthy tear production and eye comfort.

If you spend long hours at a computer or on devices, implement the 20-20-20 rule and ensure your workstation is ergonomically set up. Position your screen at arm's length and slightly below eye level. Adjust lighting to reduce glare, and consider using a matte screen protector.

In dry environments, use a humidifier to add moisture to the air, especially during winter when heating systems dry out indoor air. Drink plenty of water throughout the day, as hydration affects tear production. When outdoors in windy, dusty, or sunny conditions, wear wraparound sunglasses to protect your eyes from irritants and UV radiation.

How Is Red Eye Diagnosed?

Red eye is diagnosed through patient history and physical examination. Doctors assess symptom onset, associated symptoms, vision changes, and risk factors. Examination includes visual acuity testing and slit-lamp microscopy to evaluate the conjunctiva, cornea, and deeper structures. Additional tests may include pressure measurement or cultures.

When you see a healthcare provider for red eyes, they'll use a systematic approach to determine the cause and severity of your condition. The diagnostic process typically begins with detailed questions about your symptoms and medical history, followed by a careful examination of your eyes.

The history helps narrow down possible causes by identifying patterns in your symptoms. Your doctor will ask about when the redness started, whether it came on suddenly or gradually, what symptoms accompany it, whether you've had recent infections or injuries, and what treatments you've already tried. They'll also ask about contact lens use, allergies, and any medications you take.

Physical Examination

The eye examination begins with assessing your visual acuity, as vision changes can indicate more serious conditions. Your doctor will examine the external structures of your eye, including the eyelids, eyelashes, and the pattern of redness (localized vs. diffuse, around the iris vs. throughout the conjunctiva).

A slit-lamp examination uses a specialized microscope with a bright light source to examine the eye in detail. This allows visualization of the cornea, anterior chamber, iris, and lens. The doctor can detect subtle findings like corneal ulcers, cells in the anterior chamber (indicating inflammation), and abnormal pupil responses.

Additional Tests

Depending on the suspected diagnosis, additional tests may be performed. Intraocular pressure measurement is important if glaucoma is suspected. Fluorescein staining involves placing orange dye on the eye's surface to reveal corneal damage or ulceration under blue light. In some cases of severe or recurrent infection, cultures may be taken to identify the causative organism.

If a systemic condition is suspected as the cause of eye inflammation, your doctor may order blood tests or refer you to other specialists for evaluation. Conditions like autoimmune diseases, connective tissue disorders, and certain infections can cause recurrent eye inflammation.

How Is Red Eye Treated?

Treatment depends on the cause. Viral conjunctivitis is treated supportively with artificial tears and cold compresses. Bacterial conjunctivitis may require antibiotic drops. Allergic conjunctivitis responds to antihistamines and avoiding triggers. Serious conditions like keratitis, iritis, or glaucoma require specific medical or surgical interventions.

The treatment of red eye is directed at the underlying cause, which is why accurate diagnosis is so important. What works for one type of red eye may be ineffective or even harmful for another. Your doctor will tailor treatment recommendations based on the specific condition identified during evaluation.

It's important to complete the full course of any prescribed treatment, even if symptoms improve before the medication runs out. Stopping treatment early, especially with antibiotic drops, can lead to recurrence or development of resistant bacteria.

Treatment for Infectious Conjunctivitis

Viral conjunctivitis has no specific cure and typically resolves on its own within 7-14 days. Treatment is supportive: artificial tears for comfort, cold compresses for swelling, and good hygiene to prevent spread to others. Antibiotics are not effective against viruses and should not be used for viral conjunctivitis.

Bacterial conjunctivitis may be treated with antibiotic eye drops or ointment. Common options include fluoroquinolones, aminoglycosides, or macrolide antibiotics. Treatment typically lasts 5-7 days. Antibiotic treatment can shorten the duration of symptoms and reduce the contagious period, making it easier to return to work or school.

Treatment for Allergic Eye Conditions

Allergic conjunctivitis is treated with a combination of allergen avoidance and medication. Over-the-counter antihistamine/mast cell stabilizer eye drops can provide rapid relief of itching and redness. Oral antihistamines may also help, especially if you have other allergy symptoms like nasal congestion.

For more severe or persistent allergic eye disease, your doctor may prescribe stronger medications including corticosteroid eye drops (for short-term use only) or immunomodulatory drops. Allergy testing and immunotherapy may be recommended for people with severe, recurrent allergic eye symptoms.

Treatment for Other Red Eye Conditions

Dry eye syndrome is treated with artificial tears, lifestyle modifications, and addressing underlying causes. For moderate to severe dry eye, prescription medications like cyclosporine or lifitegrast drops can reduce inflammation and improve tear production. Punctal plugs may be inserted to help tears stay on the eye's surface longer.

Styes and blepharitis are treated with warm compresses, lid hygiene, and sometimes antibiotic ointments. Most styes don't require antibiotics and resolve with conservative care. Chronic blepharitis may require long-term management strategies including omega-3 supplements and regular lid cleaning.

Serious conditions like keratitis, iritis, and acute glaucoma require specific treatments. Keratitis is treated with intensive antimicrobial drops tailored to the causative organism. Iritis requires corticosteroid drops and dilating drops to prevent complications. Acute glaucoma is a medical emergency requiring immediate treatment to lower eye pressure, potentially including surgery.