1, allergic reaction: Some people are allergic to crystal, resulting in redness, itching or shortness of breath.

2, neck discomfort: the shape and height of the crystal pillow is not suitable for everyone's head and neck, leading to neck bending or excessive stretching, causing neck pain or discomfort.

3, temperature regulation problem: crystal is usually slightly lower than body temperature, so long-term use leads to cold or uncomfortable head.