Yes, there are many controversies. Examples include:

• The mechanism(s) by which magnets might relieve pain have not been conclusively identified or proven.
  
  
• Pain relief while using a magnet may be due to reasons other than the magnet. For example, there could be a placebo effect or the relief could come from whatever holds the magnet in place, such as a warm bandage or a cushioned insole.^22,24
  
  
• Opinions differ among manufacturers, health care providers who use magnetic therapy, and others about which types of magnets (strength, polarity, length of use, and other factors) should be used and how they should be used in studies to give the most definitive answers.
  
  
• Actual magnet strengths can vary (sometimes widely) from the strengths claimed by manufacturers. This can affect scientists' ability to reproduce the findings of other scientists and consumers' ability to know what strength magnet they are actually using.^26,31,32