According to Baidu Encyclopedia, forehead cupping can stimulate the acupoints and meridians on the forehead, which can better dredge the meridians.

Cupping is a common physical therapy method in traditional Chinese medicine. Cupping mainly uses a can as a tool to burn the air in the can by burning fire to generate negative pressure, which is then adsorbed on the surface of human skin. Has the effects of dredging channels and collaterals, relieving swelling and pain, expelling wind and dispelling cold.