What causes bloodshot eyes?

 Medically reviewed by Alastair Lockwood on 11 November 2020

What causes bloodshot eyes?

Bloodshot eyes can be caused by various factors. This includes when the eye becomes irritated, either through your environment via airborne irritants, such as pollution, substances entering the eye, allergies, or from an eye condition. The bloodshot appearance is the result of when the tiny blood vessels in your eyes expand. Whilst red eyes are usually no cause for concern, they can sometimes be a symptom of an eye disease that requires medical attention.

The most common causes of bloodshot eyes include:

• Allergies
• Wearing your contact lenses for too long
• Eye infection or disease
• Ingrown eyelashes
• Burst blood vessel
• Smoke
• Dry eyes
• scratch to the cornea/grit in the eyes

Bloodshot eyes are not necessarily a cause for concern. The cause of bloodshot eyes can be anything from too much time looking at screens to a lack of sleep. However, when pain is a symptom alongside red eyes it can be a sign of something more serious.

When bright red eyes are painful, it could be one of the following:

• An eye infection
• Dry eye syndrome
• Conjunctivitis (pink eye)
• Wearing your contact lens too long or improper contact lens care regime
• Computer vision syndrome

How to get rid of bloodshot eyes

You can get rid of bloodshot eyes in a variety of ways. You could try a soothing cold compress held on closed eyes. If this doesn’t work, a warm (not hot) compress could be more effective. If your eyes feel tired, some lubricating eye drops (or artificial tears) could help alleviate your symptoms. These drops mimic your natural tears to help reintroduce moisture to the eyes.

If you’re concerned about your red eyes or they are very painful, seek advice from your optician. They'll help you discover the underlying cause as well as the most effective treatment options.

When should you see a doctor for red eye?

If you experience any of the following symptoms alongside your red eyes, seek medical attention immediately:

• You can't open your eyes/ experience pain when you attempt to open your eyes
• You have a severe headache
• Your eye or eye area is swollen
• Nausea, fever or vomiting
• Your vision is blurry or becomes worse

Even if your irritated eyes don't feel like enough of an emergency, it's worth visiting your optician if your symptoms persist for more than a few days.

How to prevent bloodshot eyes

Some ways to avoid getting bloodshot eyes: