Not when used correctly. But if used incorrectly, magnetism can stress a site already stressed. It is a very specific science and must be applied correctly. Foundation for Magnetic Science teaches and explains exactly how to place the BioMagnets.
In basic physiology, (Dr. Robert Becker, The Body Electric) it has been found that a traumatized site immediately sends a signal to the brain which in turn sends Negative energy to [raise the Zeta potential] heal the site. Bio Negative biomagnetic energy is simply an amplified form of the body's natural electrical healing energy. When Bio-North Negative energy is applied on the Negative Polarity of the site, the energy supports and increases the body's ability to reduce swelling and pain.
Warning - there are bi-polar and multi-polar pads that are sold for pain relief.
Scientifically, when both poles are together, the field emitted will have a 7-14% aggregate of Bio South Positive energy since it is the expanding pole. Positive (reduced Zeta potential) energy is the body's weakened energy from trauma or stress. The bi-polar or multi-polar pads Positive energy works against acquiring the proper Zeta potential.
Positive [Bio-South] energy creates acidity in the blood and increases Positive energy which is the same charge state as free radicals. Using Negative field energy has been shown to help to charge and normalize the alkaline/acidity balances where applicable.
It has been found that the Positive field is useful in specialized circuits and sparingly used in normalizing hypo [slow reacting] organ/glands - these issues are shown in the advanced protocols and Magneto-Diagnostics in the "Conquer Pain" Book
Taken from Amega Website
