Everytime there is a epidemic viral going around, there were postings which suggested Influenzinum to be the prophylactic. This has no basis and such posts are misleading.
H. C. Allen in his NOSODES clearly mentions that Influenzinum should be taken only by the patient who has contracted the virus. and Ars is the prophylactic.
Here is the reference:
When “colds” appear in a family let all those who are unaffected take Arsen. 3 thrice daily, and let the patients take Influ. 30 every hour or two. This generally prevents the spread of the trouble and clears up the “colds”, whether they are of the influenza type or not. Influenza has the property of developing old troubles, and thus it takes an infinite variety of forms in different persons, so that Influ., need not be expected to cure all cases unaided, or indeed, to be appropriate to every case.
