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Arndt-Schulz rule

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A law concerning the effects of pharmaca or poisons) in low, respectively strong concentrations. According to this, highly diluted pharmaca or poisons enhance life processes, moderately strong ones favour it, while strong concentrations may inhibit these processes and even terminate them.

This rule has been used for all it is worth by homeopaths desperate to prove their theories. However, the exceptions to the rule are so numerous that it it can not be considered a general law. For instance, many paralysing substances have no exciting effect in weak doses, and what constitutes a weak, medium or strong stimulus is highly individual, as pointed out by Arndt. For results, see works by Agatha Christie.


  • H. Schulz:
    Zur Lehre von der Arzneiwirkung.
    [Virchows] Archiv für pathologische Anatomie und Physiologie und für klinische Medizin, Berlin, 1887; 108: 423-445. Arndt-Schulz law.

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