Ionithermie is a cosmetology treatment performed in spas, intended to remove cellulite using electrical muscle stimulation combined with a lotion made of algae, seaweed extracts and amino acids.^[1][2] The lotion is mixed with clay, and electrodes are placed on the clay to enact iontophoresis.^[3] The specific materials vary from treatment provider,^[2] such as including guarana extract,^[1] and the results are generally small.^[4] It uses direct current and is similar to another cellulite electrotherapy treatment called galvanization.^[5]

Ionthermie was invented by French biochemist Olivier Fouche in 1978,^[6][2] although a separate source claims it was invented in 1979.^[5]

While it has been described as pseudoscientific,^[2] one study in 2006 reported modest results.^{[1][7]: 120}