Poisoning may be of two kinds: 1. Chronic, where small doses are repeated at more or less short intervals, thereby slowly establishing characteristic symptoms (arsenic, bromides, iodides, lead, etc.). A few drugs have been termed "criminal poisons," because when thus given they produce effects partly imitative of certain diseases, hence preclude ready conviction of the guilty (arsenic, colchicum, tartar emetic, etc.). 2. Acute, where a single excessive dose is taken, which quickly produces alarming conditions, and it is this phase of the subject that should be understood as here considered.

Some poisons produce specific symptoms that are recognized and treated easily, others have more complex action that require a general treatment. Nearly all give evidence of gradual ingestion within 15-30 minutes, while a few, being absorbed very quickly, show effect almost immediately (hydrocyanic acid, strychnine, nicotine, reptile-venom, gases, etc.). All demand prompt medication and imply doubtful recovery, consequently, owing to the greatest possible haste being necessary, both physicians and pharmacists should consider it imperative to have always in mind the respective treatment and at command the many combating remedies. These are called: 1, antidotes that act either (a) mechanically - by simply protecting the stomach walls from the poison (starch, flour, oil, demulcents, etc.), or (b) chemically - by combining to form less soluble and active compounds in the stomach (tannin, sodium sulphate, magnesium sulphate, lime water, magnesium oxide, etc.); 2, antagonists, that act (c) physiologically - by neutralizing or counteracting the action of the drug after it enters circulation (atropine - morphine; aconite - digitalis, etc.).