Organon §251

When a medicine that has reciprocal states is not effective on first being administered, a second dose will usually be effective. 

There are some medicines whose power to alter the human condition consists, for the most part, of reciprocal actions. Examples of such medicines are ignatia, probably bryonia and rhus toxicodendron, and in part, belladonna. These medicines have initial-action symptoms that are, in part, opposed to one other. Should the medical-art practitioner find no improvement upon prescribing one of these medicines (according to strict homeopathic selection) he should give another, equally minute dose of the same medicine. He will thereby soon attain his purpose in most cases (and in cases of acute disease, after just a few hours). 206

Comment

206 I have explained this in greater detail in the preface to Ignatia in the Materia Medica Pura.