Dr. Chris Rapuano of Wills Eye Hospital says that every year, he treats people with injuries from those contacts.
Lenses to turn wearers into zombies, Dracula, or werewolves are easy to buy on the internet, at beauty supply stores, pop-up Halloween stores, and even from street vendors - all without a prescription.And that's the problem.
Dr. Rapuano says they aren't regulated, so there are no guarantees the lenses are sterile or even made from a material that is safe for the eyes.
And since they aren't fitted to YOUR eyes, there's a higher risk for an abrasion or scratch.
"They can be moderate, and cause a problem for a few weeks and causes some scarring for the vision, or they can be absolutely devastating, and people can go blind in an eye from a contact lens-related infection," he continued.
Federal agencies from the FDA to Homeland Security are also warning about the over-the-counter lenses, which are illegal.
In fact, authorities have an ongoing operation to seize the illegal lenses, called Operation Double Vision.
If you go for the lenses, get them from an ophthalmologist or optometrist.
While it may be tempting to wear the decorative lenses for just one night, eye experts say it could cause a scarier Halloween than you want.