Halloween’s just around the corner. So, it’s time to talk about the dangers of decorative contact lenses. You might think it would be cool to wear golden contacts to enhance your vampire costume, or wear red lenses with your devil getup… But it’s dangerous.

Wearing lenses that are the wrong size or shape, or aren’t sterile, can lead to an allergic reaction, swelling, conjunctivitis, cornea damage, or even blindness. That’s according to Dr. Andrea Thau, a spokesperson for the American Optometric Association.

She says the only safe way to wear contacts – colored or otherwise – is to get a checkup and prescription from an eye doctor. In fact, it’s illegal to get lenses any other way. Why? Because the FDA regulates decorative contacts as medical devices – and they need a doctor’s prescription to be sold.

So, be sure to steer clear of websites, beauty salons, and flea market vendors that sell them.