What causes bloodshot eyes?

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Dilated, enlarged blood vessels can lead to reddening on the eye surface. This redness can become prominent since the vessels grow in size on the surface of the white part or sclera. Bloodshot eyes can oftentimes indicate an underlying health issue and at other times no serious complications at all. Remember that bloodshot eyes are an issue of concern if accompanied by impaired vision or eye pain.

Eye strain

Eye strain or fatigue can cause eye redness that can be relieved if the individual allows the eyes to rest. Some individuals who are tired and suffer from eye strain might constantly rub their eyes which can worsen the issue. Oftentimes, eye strain or coughing can cause a bright red bloody area to develop on the sclera. Even though it appears serious, it is a common occurrence and typically resolves in 1-2 weeks.

Exposure to irritants

Pollen, animal dander and dust are common causes of bloodshot eyes for individuals who have sensitivities or allergies.

Pollen, animal dander and dust are common causes of bloodshot eyes for individuals who have sensitivities or allergies. Many individuals suffer from eye redness due to the presence of environmental irritants such as exposure to blowing wind, dry air or sun. Take note that dry eyes can lead to redness.

The flu and common cold can oftentimes cause bloodshot eyes specifically when complemented by coughing, sneezing episodes or lack of sleep. Even daily activities such as taking a dip in a chlorinated pool can cause irritation of the eyes and trigger reddening. This can occur if the individual does not uses swimming goggles which provides a barrier to the water.

Eye damage

Foreign objects that damage or cut the eye can cause bloodshot eyes and require immediate medical attention. The cornea which is the exterior covering of the eye can be scratched by dust, sand or overuse of contacts lens, resulting to eye redness. As for corneal ulcers, they often result from viral or bacterial infection that leads to bloodshot eyes as well.


It is important to note that conjunctivitis involves inflammation or infection of the conjunctiva which is a membrane that covers the eye surface. This condition is considered contagious and can be caused by bacteria, virus, allergy or irritation. The itchiness and redness occurs once the eyelash follicles along the eyelid become inflamed with a condition called blepharitis where the eyelids become crusty. Bloodshot eyes occur once infection, exposure to toxins or immune conditions cause inflammation of the layer of the eyeball that surrounds the lens.

Acute glaucoma

Eye redness that is accompanied by visual disturbances and intense pain might indicate acute glaucoma which is an abrupt increase in the eye pressure. Medical care is required for this condition that can threaten the eye sight.

Once an individual ends up with bloodshot eyes, it is best to schedule an appointment with a doctor for proper assessment of the condition as well as provide the suitable form of treatment.

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