The beauty of colored contacts—the ability to change your eyes from blue to green to just about any color under the sun. There are also costume contact lenses available that can make your eyes look feline, vampiric, or even reptilian. Pull a Marilyn Manson and make one eye color different from the other. Give yourself a slit eye on one side and a stunning blue wolf eye on the other, you get the idea.

However, color contact lenses—also sometimes referred to as decorative or cosmetic lenses—are not without risks and hazards. Yes, they can do amazing and even otherworldly things to your visual appeal, but there could be serious consequences to your eye health if you’re not intelligent and vigilant. The most important thing is to first make sure they are FDA approved. Trusted online contact lens retailers like Lens.com carry lenses that are FDA approved. The following are the pros and cons of colored contacts:

Pros

You can change up your look. Who doesn’t want to look like someone else once in a while? Color contact lenses allow you to experiment with being blue-eyed, green-eyed or even violet-eyed. Designer colors and looks are readily available for those who want to change it up even for just a day.

You can make a Halloween costume extra-rad. Costume contact lenses allow for taking on the eyes of just about any creature under the sun—cat, wolf, snake—so you can really take a costume idea to the next level. It’s also possible to look uber-otherworldly; you could emulate an alien, dragon, or the undead.

Non-corrective lenses are available. Colored and costume contacts are available in non-corrective varieties for those who don’t need vision correction but still want to look awesome.

Cons

Costume lenses are sometimes marketed as harmless toys. Many non-prescription costume and colored contact lenses are marketed in the same way that a cat suit or furry bunny ears are advertised—like a harmless costume component or toy. The truth is that even non-prescription contacts have eye health risks and their purchase should be overseen by an eye care professional.

One size does not fit all. Despite costume manufacturer claims that anyone can wear their lenses, the truth is that not everyone is a candidate for wearing contact lenses for any length of time. Eyes should be thoroughly checked for readiness to wear contact lenses and fitted properly, otherwise serious health consequences could result.

Eyes are sensitive! Even in the best of circumstances, people who don’t normally wear contact lenses always need an adjusting or acclimation period to get fully used to their new lenses. Colored or not, eyes can react to contact lenses with irritation, fatigue and even soreness. As cool as those contacts look, they could be a recipe for ruining your evening out as a blue eyed gal or making the costume party a drag.

Eye injuries and diseases are possible. Costume and colored contacts without a prescription may not be the right fit and cause cuts to the eye that can even lead to corneal abrasions and ulcers (open sores over the pupil and iris and pupil). A bacterial infection called keratitis can also result; in fact, studies have shown those who wear costume contacts are over 16 times more likely to get keratitis than those who wear prescription corrective lenses. Sixty percent of the people in one study sustained permanent vision loss.

Serious eye damage is possible. In extreme cases, wearing contacts without the supervision of a health professional can lead to vision loss and even blindness. Yes, this might sound alarmist, but in extreme cases, it is possible. There are documented spikes in people visiting ophthalmologists around Halloween.

So, if you want to look like a wolf, zombie, cat, or just a blue-eyed version of yourself, see an ophthalmologist first. Make sure you are a good candidate for color contact lenses or animal eyes, and preserve your vision for your real life.