Bloodshot eyes are often associated with late nights followed by early morning obligations. 

While this is indeed one cause of irritated eyes, other factors can contribute to the condition.

To get a clear understanding of the triggers and treatments for bloodshot eyes, Fox News Digital consulted with two ophthalmologists, who provided eye-opening insights.

What causes bloodshot eyes?

When the eyes get irritated, the tiny blood vessels on the white surface of the eye (the sclera) swell, said Usiwoma Abugo, M.D., an ophthalmologist at Katzen Eye Group in Lutherville, Maryland. 

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When this happens, the white of the eye appears pink or red, she noted.

There are many potential causes of red or bloodshot eyes. 

Bloodshot eye

When the eyes get irritated, the tiny blood vessels on the white surface of the eye swell, which makes it appear pink or red. (iStock)

"They can be a response to an irritant such as pollen, pets, dust or smoke, or a symptom of a medical condition, such as a bacterial infection, virus or injury to the cornea," Abugo told Fox News Digital. 

Here’s some more information on some of the primary culprits.

Allergies

When an allergen gets into the eye, the eye responds by producing a substance called histamine, Abugo said.

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This causes the blood vessels on the surface of the eye to get leaky and swollen, which creates redness and swollen, itchy tissues.  

Dry eyes

"Dry eye is an incredibly common eye condition," Abugo told Fox News Digital. 

"When the eye doesn’t have enough tears to stay lubricated, the eye becomes red, and the horizontal blood vessels on the surface of the eye become more prominent, swollen and irritated."

Tiredness

There’s a reason an overnight flight is called the "red-eye" — bloodshot eyes are often caused by being tired, which is usually related to dry eye, the doctor said.

Allergy

Allergies are a common cause of bloodshot eyes, according to experts. (iStock)

"When you are tired, your body's natural tearing or lubrication system becomes abnormal, leading to dry eye," she noted.

Contact lenses

Poor contact lens hygiene or poorly fitted lenses can irritate the eye and lead to redness.

Not cleaning or caring for your lenses correctly could even lead to a serious eye infection, Abugo warned.

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"Make sure to care for your lenses as recommended by your eye care team, remove them as prescribed, and only wear lenses prescribed for you by a professional," she advised. 

Eye infections

Conjunctivitis, commonly known as pink eye, can be caused by bacteria or a virus

The condition causes the surface of the eye to swell, which gives the eye a pink or red color, said Abugo.

Relieving and preventing bloodshot eyes

Michelle Andreoli, M.D., an ophthalmologist at Northwestern Medicine in Naperville, Illinois, shared with Fox News Digital some tips for treating red eyes at home.

Over-the-counter artificial tears can be used to address irritation and wash allergens from the eye. 

Pink eye split

An opthamologist said to avoid decongestant (anti-redness) drops, because "they don’t solve the cause of the problem and can sometimes make redness worse in the long run." (iStock)

Avoid decongestant (anti-redness) drops, Andreoli advised, because "they don’t solve the cause of the problem and can sometimes make redness worse in the long run."

Instead, she suggested using over-the-counter antihistamine drops to help with itchy eyes caused by seasonal allergies. (Always check with a doctor first.) 

A cool compress can also provide some relief.

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To prevent redness, Anderoli said to avoid smoke, fumes, pollen, dust, chlorine or pet dander if those are known irritants.

Wash your hands often, avoid touching your eyes and wash eyelids daily with a mild cleanser, she recommended.

"If you do have an eye infection, your doctor will prescribe antibiotic eye drops or other medication as deemed appropriate," the doctor said.

When to see a doctor

Bloodshot eyes are very common and rarely indicate something serious, according to Andreoli.

If symptoms aren't improving after one week of home remedies, however, she recommends seeing an ophthalmologist for diagnosis and treatment.

blue eye contact lens

Contact lenses can cause redness for some people, especially when they are not cleaned or cared for properly.  (iStock)

Some of the more serious conditions associated with bloodshot eyes are ocular inflammation (called uveitis) or an eye infection. 

In that case, there are usually additional symptoms, such as pain, discharge and blurred vision. 

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"If not treated, eye infections can sometimes cause devastating damage, including vision loss," Anderoli said.

"Luckily, effective treatments are available to avoid this worst-case scenario."

If eye redness is accompanied by any degree of vision loss, contact your eye care provider immediately, the doctor advised.

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The American Academy of Ophthalmology recommends that all healthy adults get an eye exam by the age of 40 to catch any signs of eye disease. 

Added Anderoli, "Lots of eye conditions and diseases can be treated when caught early enough, but often begin without any noticeable symptoms."

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