An all-nighter at your computer. A bout of allergies. Smoke from a friend’s cigarette. Plenty of things can leave your eyes red and irritated. And there are plenty of reasons that you need the redness to go away as fast as possible.

When eye redness strikes, it’s only natural to reach for a bottle of redness-relieving eyedrops. After all, that’s what they’re for, right?

Not so fast. Using redness-relieving eyedrops can leave your eyes looking redder — and feeling more irritated — than before. It’s so common that there’s even a name for this: rebound redness.

That’s why you’ll want to use these drops sparingly if you decide to use them at all, according to Raul Ramos, O.D. He’s an optometrist whose practice is located within an America’s Best Contacts & Eyeglasses in Miami.

Here’s what you need to know about red-eye drops, including how to use them safely and when to skip them.

Have questions about your eye health or vision? Your America’s Best optometrist is here to help! Find an exam time that fits your schedule.

How Redness-Reducing Eyedrops Work

Many things can irritate your eyes and trigger the telltale redness, including:

• Allergies
• Being near chemicals
• Fatigue
• Leaving your contact lenses in too long
• Long stints in the sun and/or wind
• Smoke

You’re probably familiar with nasal decongestants. They relieve stuffiness by reducing the swelling in your nose’s blood vessels. Many red-eye drops also contain a decongestant, which works similarly in your eyes.

When your eyes become irritated, the tiny blood vessels on the surface of your eyes expand. This makes it look as if the whites of your eyes are, in fact, red, according to the American Academy of Ophthalmology (AAO).

Red-eye drops such as Visine® and Clear Eyes® Redness Relief work by “squeezing the blood vessels in the eye,” says Dr. Ramos. This reduces blood flow, and oxygen, to your eyes, which makes your eyes appear whiter.

Rebound Redness Explained

The problem? Once you stop using the drops, those blood vessels open up again. This causes more blood and oxygen to flow into the area, triggering even more redness than before, Dr. Ramos explains.

“The redness comes back more aggressively, to the point where you’ll have to continue using the drops to take away the redness,” he says.

Eventually, though, the red-eye drops will stop working, and you may be left with longer-lasting redness. Hence the name rebound redness.

Now that you have a better understanding of the rebound effect, these facts will help you safely find relief.

Fact #1: Use Red-Eye Drops Sparingly

Knowing the risk of rebound redness, Dr. Ramos says to avoid turning to red-eye drops for regular relief. In fact, you probably shouldn’t use them for more than three days in a row, he says.

“The only time I recommend these drops to patients is if they’re going to a wedding and need to take pictures,” says Dr. Ramos.

Fact #2: Remove Contact Lenses Before Using Red-Eye Drops

If you put redness-relieving drops on top of your contacts, the drops can be absorbed into the lens itself, Dr. Ramos explains.

If you’re going to use them:

• Remove your contacts
• Put the drops in according to the package directions
• Wait at least 15 minutes before inserting your contact lenses
• During this time, try to give your eyes a break by resting

Fact #3: Frequent Eye Irritation May Signal a More Serious Eye Problem

Red eyes often go away on their own, says Dr. Ramos. But that’s little consolation if you have bloodshot eyes on date night or while you’re presenting at a meeting.

If you slept poorly or have allergy symptoms, you can often guess why your eyes are red. That said, red eyes sometimes signal a more serious eye condition, such as glaucoma, dry eye, pink eye, or uveitis (a redness and inflammation of the eye that can cause vision loss). Conditions such as Sjögren’s syndrome and lupus can also cause red eyes, Dr. Ramos says.

“Before you use a redness-remover drop, the main rule is to figure out what the cause of the problem is,” he says. “The drops only hide the underlying condition.”

If you have frequent eye redness, schedule an eye exam so that your optometrist can check the health of your eyes.

Sometimes red-eye symptoms need quick attention to rule out serious complications or problems, according to Dr. Ramos. This includes:

• If you’re also experiencing blurry vision, discharge, or pain
• If your eyes suddenly become red or bloodshot
• If only one eye is red while the other remains white

Fact #4: Red-Eye Drops Are Not Safe if You Have Glaucoma

If you have a type of glaucoma called narrow-angle glaucoma (or narrow-anterior chamber glaucoma), don’t use decongestant red-eye drops. Doing so can cause a medical emergency called an acute-angle glaucoma attack.

In narrow-angle glaucoma, a person’s iris (the colored part of the eye) is very close to the eye’s drainage angle, where fluid leaves the eye. When you use redness-relieving drops, your pupil dilates slightly, which could block the drainage canal. If this happens, fluid can build up, raising the pressure in your eye and triggering severe pain, redness, and nausea.

This acute-angle attack is an emergency. So if you start experiencing these symptoms, call your doctor and immediately go to the emergency room.

Fact #5: You Have Options Other Than Red-Eye Drops

Red-eye drops aren’t the only way to find quick relief. First, though, it’s important to talk to your eye doctor, who can help uncover the cause of your redness. Once you know what’s triggering the problem, you can figure out alternative ways to find relief.

For example, if you have redness from allergies, over-the-counter (OTC) antihistamine eyedrops can help tame the trigger. They relieve both the redness and itchiness in your eyes.

Or, if your eyes are dry — say, from working on the computer all day — OTC artificial tears will serve you better than red-eye drops. Artificial tears are lubricating drops that contain some of the natural fluids found in your eyes. You can also place cool or warm compresses over your eyes a few times a day to ease redness.

For those times when you do need a redness-relieving eyedrop, Dr. Ramos recommends Lumify® Redness Reliever Eye Drops. He says these particular drops work a little differently from other drops on the market. Other red-eye drops constrict certain arteries that carry oxygen into the eyes. But Lumify targets veins, which don’t interrupt oxygen flow to the eyes, he says.

Lots of people struggle to put eye drops in correctly. Press play for some simple tips that can help.