Delirium is the commonest organic mental disorder in clinical practice.  Delirium is an acute generalize impairment of brain function, in which the most important feature is impairment of consciousness. The disturbance of brain function is generalized, and the primary cause is often outside the brain; for example, sepsis due to a urinary tract infection. 
Delirium is the most appropriate substitute for a variety of names used in the past such as acute confusional states, acute brain syndr ome, acute organic reaction, toxic psychosis, and metabolic (and other acute) encephalopathies. 
Sign & Symptoms:
- Impaired consciousness
- Poor attention and concentration
- Loss of memory Behaviour
- Under active Thinking
- Muddled (confused)
- Ideas of reference
- Delusions Mood
- Anxious, irritable
- Hallucinations, mainly visual
- Acute onset, fluctuating course, worse in the evening
Impairment of consciousness is the most important symptom, and is seen as a deficit of attention, concentration, and awareness. Often the patient will not be able to follow or engage in a logical conversation. The features fluctuate in intensity and are often worse in the evening.
Disorientation: Uncertainty about the time, place, and identity of other people.
Behaviour may be either overactive, with noisiness and irritability, or underactive. Sleep is often disturbed.
Thinking is slow and confused but the content is often complex. Ideas of reference and delusions are common.
Mood may anxious, perplex, irritable, or depress and is often labile.
Perception may distort with misinterpretations, illusions, and visual hallucinations. Tactile and auditory hallucinations occur but are less frequent.
Memory Disturbance of memory affects registration, retention, and recall, as well as new learning.
Insight is impaired. 
i. Hypoxia, Carbon dioxide narcosis
iii. Hepatic encephalopathy, Uremic encephalopathy
iv. Cardiac failure, Cardiac arrhythmias, Cardiac arrest
v. Water and electrolyte imbalance (Water, Na+, K+, Mg++, Ca++)
vi. Metabolic acidosis or alkalosis
vii. Fever, Anaemia, Hypovolemic shock
viii. Carcinoid syndrome, Porphyria
viii. Carcinoid syndrome, Porphyria
i. Hypo- and Hyperpituitarism
ii. Hypo- and Hyperthyroidism
iii. Hypo- and Hyperparathyroidism
iv. Hypo- and Hyperadrenalism
Drugs (Both ingestion and withdrawal can cause delirium) and Poisons:
i. Digitalis, Quinidine, Antihypertensives
ii. Alcohol, Sedatives, Hypnotics (especially barbiturates)
iii. Tricyclic antidepressants, Antipsychotics, Anticholinergics, Disulﬁram
iv. Anticonvulsants,, L-dopa, Opiates
v. Salicylates, Steroids, Penicillin, Insulin
vi. Methyl alcohol, heavy metals, biocides
i. Thiamine, Niacin, Pyridoxine, Folic acid, B12
ii. Proteins Systemic Infections i. Acute and Chronic, e.g. Septicaemia, Pneumonia, Endocarditis
i. Epilepsy (including postictal states)
ii. Head injury, Subarachnoid haemorrhage, Subdural haematoma
iii. Intracranial infections, e.g. Meningitis, Encephalitis, Cerebral malaria
v. Stroke (acute phase), Hypertensive encepha lopathy
vi. Focal lesions, e.g. right parietal lesions (such as abscess, neoplasm)
i. Postoperative states (including ICU delirium) ii. Sleep deprivation iii. Heat, Electricity, Radiation. 
The diagnosis is clinical and is usually obvious upon talking to the patient. Typically, a standard medical and surgical history is take, rather than a formal psychiatric interview. Often little history can be obtained from the patient, so it is essential to contact relatives, carers, friends, and other clinicians in order to gather the story.
Include a comprehensive list of medications, including over-the-counter remedies, alcohol, and smoking. A full examination of all physical systems should undertak, including a detailed neurological examination.
Physical investigations should include the following:
● Blood for full blood count, urea and electrolytes, liver function tests, thyroid function tests, calcium, phosphate, magnesium, glucose, lactate, troponin, albumin, paracetamol and salicylate, haematinics;
● Blood and urine cultures;
● Arterial blood gas;
● Chest X-ray;
● Consider further tests, e.g. CT head, lumbar puncture, EEG.
● Abbreviated Mental Test Score (AMTS): Out of 10 points, a score of 6 or less is taken as delirium.
● Mini Mental State Examination (MMSE): 30 points, with more than or equal to 25 taken as normal, mild dementia 21–24, moderate 10–20, and severe less than 10 points. 
1. Treat the underlying cause:
This obviously depends on the exact aetiology, but frequently involves giving oxygen, fluids, antibiotics, and pain relief, as well as any specific treatments. Intravenous access (and other invasive procedures) should only be undertaken if there is a valid indication.
2. Reassurance and reorientation:
Patients need reassurance to reduce anxiety and disorientation; this should be repeated frequently. A clock should be visible at all times, and the patient reminded of the time, place, day, and date regularly.
3. Predictable, consistent routine:
On the ward the patient should be nursed either in a quiet side room or next to the nursing station. It should be reasonably dark at night and light during the day. Meals and activities should occur at standard times each day. Relatives and friends should be encouraged to stay or to visit frequently.
4. Avoid unnecessary medications.
5. Explain to relatives and friends:
what delirium is and what has caused it. This helps them to reassure and reorientate the patient.
It is often disturb, and it is reasonable to give small doses of hypnotics (e.g. zopiclone 3.75 mg) or benzodiazepines (e.g. temazepam 10 mg) at night to promote sleep. Benzodiazepines should avoide during daytime as their sedative effects may increase disorientation. The exception to this is in alcohol withdrawal or in order to treat seizures.
7. Disturbed, violent, or distressed behaviour:
It may treat with carefully monitored antipsychotic medications. There is good randomized control evidence supporting the use of antipsychotics in delirium, with a consistent two thirds of patients experiencing clinical improvement.
Haloperidol is the traditional choice, 0.25–2 mg every 4 hours, although atypical antipsychotics are becoming more commonly use. Haloperidol is available in oral, intramuscular, and intravenous preparations.
Olanzapine has shown to be just as effective at relieving agitation as haloperidol, but the intramuscular formulation is not widely available.
Lorazepam is also effective, but has a moderate risk of worsening the mental state. If a patient is acutely distress or agitate, an IM dose is usually needed, with follow-on treatment orally for as long as necessary.
This should be regularly reviewed, and never used unless other methods of management have been exhausted. 
Homeopathic Medicine for Delirium:
Belladonna comes to mind first in delirium. It has a violent delirium with loud laughing screaming out, and grinding of the teeth, and, as in all narcotics, a desire to hide or escape. The patient is full of fears and imaginings, and the delirium manifests itself by the most positive ebullitions of rage and fury. Its general character is one of great activity with great excitement, a hot face and head and oftentimes there is present a sensation as if falling and the patient clutches the air. Sometimes there is a stupor, and when aroused they strike people bark and bite like a dog and are most violent.
This remedy has not the intensely high degree of maniacal excitement that we find under Stramonium, nor has it the cerebral congestion that characterizes Belladonna. With Hyoscyamus there is an aversion to light, and the patient fears being poisoned; he will sit up in bed, talk and mutter all the time, and look wildly about him. There is a great deal of nervousness, whining, crying and twitching; he tries to escape from imaginary foes; a constant picking at the bedclothes and objects in the air is most characteristic. It is the remedy for that curious condition of delirium known as “coma vigil.”
With this remedy the delirium is more furious, the mania more acute and the sensorium more perverted and excited than under Belladonna or Hyoscyamus. The patient desires light and company, is very loquacious, garrulous, laughs, sings, swears, prays, curses and makes rhymes. He sees ghosts, talks . with spirits and hears voices. The head is raised frequently from the pillow, the face is bright· red, and he has a terrified expression; in fact, he seems to see objects rising from every corner to frighten him. Sometimes a silly delirium is present.
Is characterized by great talkativeness in delirium. It has also the fear of being poisoned; but the Lachesis delirium is of a low form accompanied by dropping of the lower jaw, and a characteristic is that they imagine them- selves under some super-human control.
This remedy has loquacity, with a continual changing of the subject when talking, imaginings of rats, mice, etc. It is usually dependent upon uterine disease.
Veratrum has restlessness, and a desire to cut and tear the clothing as in Belladonna; but with this remedy there is a coldness of the surface of the body and a cold sweat. The patient is loquacious, talks very loud and is frightened at imaginary things. It also has a state of frenzy or excitement, during which he indulges in shrieks, in expressions of fright and in violent cursings of those around him.
The delirium of Phosphorus is of a low typhoid type, with tendency to haemorrhage and an apathetic, sluggish, stupid state, where the patient is unwilling to talk and answers question slowly. It has also an ecstatic state, in which he sees all sorts of faces grinning at him. He has also imaginary notions, such as imagining that his body is in fragments.
The patient imagines his body in pieces or double: and scattered about, and he has to move constantly to keep the pieces together.
Here the patient imagines that he is made of glass and moves carefully for fear of breaking.
Has a delirium with a constant desire to move about.
Dr Bayes praises this remedy highly in the delirium of typhoid fever, where there are constant attempts to get out of bed and tremor of the whole body. 
- Psychiatry, Fourth Edition- Oxford Medical Publications – SRG- by Geddes, Jonathan Price, Rebecca McKnight / Ch 26.
- A Short Textbook of Psychiatry by Niraj Ahuja /Ch 3.
- Homeopathy in Treatment Of Psychological Disorders by Shilpa Harwani / Ch 17.