Acetanilid is an allopathic medicine that has been used in the past not only as a pain-killing drug (in headaches, migranes, dysmenorrhea, arthralgia, myalgia and similar disorders) but also against fever. Because of this effect it has been introduced into medicine at first under the name of antifebrin. (Also in the older homeopathic literature this remedy is mostly called Antifebrium.)
But very soon many poisoning symptoms became known which mainly occured in those patients who had either taken too much of this medicine or had used it a very long time. Apart from that, a considerable individual susceptibility has also been observed: i.e. the dose which was toxic for one patient could be harmless for another.
As far as I know homeopaths have never proved this remedy in a high potency. They have only adopted the observation of the allopathic drug picture as Acetanilidum almost exclusively consists of toxicological symptoms! That means that all the so-called side-effeds of the allopathic medicine acetanilid are exactly those symptoms after which the homeopathic remedy Acetanilidum is prescribed.
I will give an example to clarify this. Cyanosis is a conspicuous symptom of an acetanilid poisoning. (Indeed, one should hesitate to make diagnosis of an acetanilid intoxication in the absence of this sign.) Nevertheless, according to the law of similars, a high potency of Acetanilidum can be of great service in some cyanotic patients. Another example: The allopathic medicine acetanilid can produce a collapse or shock syndrome. Therefore, homeopaths may use a high potency of Acetanilidum in collapsed patients, especially if they are cyanotic with at the same time a very low pulse rate.
Acetanilid and also some other chemical substances such as aniline and its derivatives can favour the conversion of hemoglobin to methemoglobin which has lost the ability of oxygen transference. The result is a methemiglobinemia (because of that, the blood may even be chocolate-colored in severe intoxication) and a more or less clear cyanosis. But this discoloration of the skin and of the mucOus membranes may exist even when only a small amount of methemoglobin is detected in the blood.
The cyanosis has two peculiarities which have sometimes proven to be leading symptoms in the homeopathic description. Firstly, it is usually of a greyish shade, grey-blue or grey-violet, although it is sometimes also described only as livid, bluish or blue. And secondly this discoloration is, in the beginning, mostly only visible on the peripheral parts of the body especially on the fingers and fingernails, toes, ears, and nose. But it can also occur on the temporal regions, eyelids, cheeks, chin and lips and eventually on the whole surface of the body.
Anemia is another very inportant symptom. Because of the reduction in the amount of hemoglobin available for oxygen transport the methemoglobinemia causes a functional anemia. But acetanilid also has an hemolytic effect. It shortens the life span of the red blood cells (high concentrations of the drug may occasionally even cause their destruction) which sometimes results in an hemolytic anemia with all known symptoms.
One should even have in mind that a lot of symptoms of Acetanilidum, for example paleness, vertigo, weakness, dyspnea, palpitations, anginal pain, etc., can be traced back to continuously progressing anemia.