 Incomplete or insufficient blinding tends to exaggerate treatment effects, particularly where any such effects are small.<ref name="CONSORT_2001"></ref> Health claims regarding longevity and cancer treatment are implausible and unsupported by any research.More mundane health claims, most commonly about anecdotal pain relief, also lack any credible proposed mechanism and clinical research is not promising.<ref name=Pittler2008></ref>

The American Cancer Society states that "available scientific evidence does not support these claims".<ref name=acsMag> See archived online version Electromagnetic therapy is a related field.See chapter in ACS book just referenced, and archived ACS webpage on that.</ref> According to the National Center for Complementary and Integrative Health, studies of magnetic jewelry haven't shown demonstrable effects on pain, nerve function, cell growth or blood flow.<ref></ref>

A 2008 systematic review of magnet therapy for all indications found insufficient evidence to determine whether magnet therapy is effective for pain relief, as did a 2012 review focused on osteoarthritis.<ref></ref> Both reviews reported that small sample sizes, inadequate randomization, and difficulty with allocation concealment all tend to bias studies positively and limit the strength of any conclusions.