In experimentation, it provokes prostration with profound sleep, unconscious and inattentive state. Nevertheless the patient answers to external requests although with great mental and physical fatigue, he cannot fix his attention over any subject.
In practice, Acidum phosphoricum is useful in a person who has suffered a depressive action, such as loss of a dear person, loss of a property or financial position, a love deception. Moreover this depressed state can be caused by sexual indulgence, either in sexual intercourses or in masturbations. This person is usually physically and mentally weak, weary, is always looking for bed (to sleep or to have sex). In this exhausted state he's indifferent to everything, doesn't want company, doesn't want to perform any job.
This medicine is very useful for today's people, who are overwhelmed by the day-to-day stresses of modern life. Useful for those patients who became depressed after the Hong Kong Stock Market crisis, for example. It's also useful for prostration, both physical and mental, caused by diarrhoea (not always; see below) with intestinal bleeding or by grief, unsuccessful businesses and unhappy love.
It causes diarrhoea with white, watery, painless faeces, full of flatulence. In spite of the general symptom of prostration, the patient suffering from this diarrhoea is not so debilitated as it would be expected. In children it's useful for diarrhoea caused by dentition.
Children who need this medicine usually have a difficulty for sleeping, although the general weakness is present. They're lazy, full of languor, but have a difficulty to start sleeping.
These are the main clinical features observed in Acidum phosphoricum, the details can be found in a good Materia Medica (see Bibliography).