A good example of this is Voll's description of the case of a patient with chronic pyelitis. Another doctor had prescribed 2 different types of antibiotics, terramycin and aureomycin, and Dr. Voll was curious to see if both were necessary and what side effects there might be.
"I began testing and saw that the terramycin only affects the right kidney and the aureomycin only the left kidney and not vice versa.... At the same time I discovered that when the patient first held the terramycin capsules and the aureomycin capsules, indicator drops for the small intestine and colon occurred as a sign of a disturbed intestinal flora caused by the medications. Furthermore the entire values of the endocrine system, i.e., the values of the Triple Heater meridian, decreased below 50. This explained to me why fatigue occurs again and again after antibiotic treatment since this sort of treatment renders the entire hormonal system temporarily insufficient. " [Voll: The Phenomenon of Medicine Testing in Electro-acupuncture According to Voll]
A theoretical model for medicine testing's mechanism of action has been developed by the Physicist Kuo-Gen Chen. All matter has a vibrational signal, including medicines, other biological reagents, and the organs and tissues of the body. When the DC current passes through the potential space of the medicine, it becomes phase modulated, carrying the vibrational signal of the medicine with it into the body. This vibrational information then reacts with vibrational patterns already existing within the body, resulting in quasi phase matching with constructive or destructive resonance, which in turn brings about an instantaneous change in the subtle energetic properties of the point being measured.
Medicine testing can be used to test any medicine or supplement administered to patients, including allopathic, homeopathic, nutritional and herbal medicines. Most physicians use the EDSD as an adjunct to their practice. Homeopathic preparations, however, appear to be particularly useful. They are made by diluting and shaking an original substance in a process called "potentization", often to the point where not a single molecule of the original substance remains in the preparation. What remains is the vibrational signature of the original substance stored in water. Homeopathic remedies seem to work extremely well in the EDST because they are distilled samples of vibrational information with an information content that is clearer than other medicines. Though it can not yet be substantiated, medicine testing suggests that there is a similarity between the information in homeopathic remedies and the biological information that circulates through the body, primarily through the meridian system. Research in this direction may eventually lead to the verification of homeopathy's mechanism of action.
The two types of homeopathic preparations used most often in the EDST are standard remedies which are made mostly from plant matter, and nosodes, a type of remedy which is made from diseased tissue samples. Standard remedies were selected because they elicit in healthy people the same symptoms as the condition they are supposed to treat. For example, Allium Cepa, a homeopathic remedy for the common cold, causes a sore throat, runny nose, tearing, and congestion in a healthy individual. Nosodes often work similarly to standard remedies in that they cause a set of symptoms in the healthy but can counteract disease in the ill. Nosodes and standard remedies often have a similar effect during medicine testing. For example, in a person with the cold, there is a good chance that either a cold virus nosode or the remedy Allium Cepa will balance points on effected meridians.