Actually, all the contact lenses are not good for the eyes. Inappropriate wearing of contact lenses may cause the corneal congestion. In addition, long wearing contact lenses may make the eyes lack water. And the hallowean contact lenses are designed exaggeratedly. If you just wear for a short time, it is OK. Keep in mind that not wearing it more than eight hours, letting eyes have a good rest.
It is hard to say. There are so many people wear halloween contact lenses on Halloween days for fun. And it is Ok for their eyes after they worn it. But there are some people who have some disorders like glaucoma that are suitable to wear contact lenses. So, wearing halloween contact lenses cause some damages to their eyes. So to be safe, you shall get your eyes checked by an eye doctor so as to know if halloween contact lenses suit for you.