Altered mental status (AMS) is an acute change in cognitive function, psychological function, and/or and can manifest with confusion, behavioral changes, and changes in alertness ranging from hyperalertness to or even . There are many potential causes of altered mental status, including primary CNS processes, general medical conditions, substance use, and psychiatric illness. Initial management includes stabilization (e.g., definitive airway management) and screening for life-threatening acutely reversible causes (e.g., hypoglycemia, opioid overdose). are used to assess and monitor the level of neurological dysfunction. Once stabilized, a full diagnostic evaluation should be performed based on the suspected underlying etiology; this may include basic laboratory studies, ECG, head imaging, and lumbar puncture. Treatment is focused on the management of the underlying etiology in addition to providing supportive care and preventing complications.
The following are possible causes of AMS and coma. See “ ” for differential diagnoses in which consciousness is preserved (e.g., , ).
|Causes of altered mental status and coma |
|Primary CNS dysfunction|| |
|Hypoxia and/or hypoperfusion|
|Endocrine and/or metabolic|| |
Causes of altered mental status and coma: AEIOU TIPS (Alcohol, Epilepsy/Electrolytes/Endocrine, Insulin, Overdose/Oxygen, Uremia, Trauma/Temperature, Infection, Poisons/Psychiatric, Stroke/Seizures/Shock) 
Gradual onset of AMS or coma suggests infection, metabolic processes, or an enlarging space-occupying lesion. 
The following conditions can mimic coma. See “ ” for underlying etiologies.
- Conditions in which consciousness is preserved but the patient cannot produce voluntary movements or motor responses 
Psychogenic unresponsiveness: an unresponsive state caused by an underlying psychiatric disorder 
- Etiologies include mood disorders, psychotic disorders, ,
- Clinical features include:
- Diagnosis based on typical examination findings, e.g.: 
- Active resistance to eye opening
- Purposeful diversion of the arm when held above the face and dropped
The differential diagnoses listed here are not exhaustive.
Altered mental status can manifest as:
- Coma manifests as depressed consciousness with no response to voice, pain, or other stimulation.
- Clinical features of underlying AMS etiologies may be present, e.g.:
- Use coma scores (e.g., , , ) for a more objective and reproducible assessment.
- Document the score upon presentation.
- Frequently reassess to detect changes early.
An abbreviated scale that helps rapidly classify and communicate a patient's level of consciousness in emergency settings. 
- A: Alert
- V: responsive to Verbal stimuli
- P: responsive to Painful stimuli
- U: Unresponsive
Glasgow coma scale (GCS) 
A standardized scale used to assess the level of consciousness and neurological status in multiple settings, e.g., . GCS is less useful in intubated patients and does not provide a detailed assessment of brainstem function.
|Glasgow coma scale (GCS) |
|Eye opening (E)||Spontaneous||4|
|To verbal command||3|
|Closed due to local factor (e.g., ocular injury)||Nontestable|
| Verbal response (V) ||Oriented||5|
|Other factor(s) interfering with communication (e.g., intubation)||Nontestable|
|Best motor response (M)||Follows instructions||6|
|Localizes pain stimulus||5|
|Withdraws from pain (normal flexion to pain)||4|
|Decorticate posturing (abnormal flexion to pain)||3|
|Decerebrate posturing (extension to pain)||2|
|No motor response||1|
|Preexisting factor(s) causing paralysis||Nontestable|
Full Outline of UnResponsiveness (FOUR) score 
|Full Outline of UnResponsiveness (FOUR) score |
|Eye response (E)|| |
Tracking or blinking to command
|Eyelids open spontaneously or to command||3|
|Eyelids closed but open in response to loud voices||2|
|Eyelids closed but open in response to pain||1|
|Eyelids remained closed in response to pain||0|
|Motor response (M)||Can make thumbs up, fist, or peace sign||4|
|Localizes pain stimulus||3|
|Flexion response to pain||2|
|Extension response to pain||1|
|No response to pain or generalized myoclonus status epilepticus||0|
|Brainstem reflexes (B)||Pupil and corneal reflexes present||4|
|One pupil wide and fixed||3|
|Pupil OR corneal reflexes absent||2|
|Pupil AND corneal reflexes absent; cough reflex present||1|
|Absent pupil, corneal, and cough reflexes||0|
|Respiration (R)||Not intubated; regular breathing pattern||4|
|Not intubated; irregular breathing pattern||2|
|Intubated; breathing above ventilator rate||1|
|Intubated; breathing at ventilator rate or apnea||0|
The goal of initial management is to identify and treat rapidly reversible and/or time-sensitiveprior to a full diagnostic evaluation.
Initial evaluation 
See also: “Evaluating disability in the ACBDE approach.”
- Perform an .
- Identify .
- Calculate (or delirium). for suspected
- Check .
- Start continuous cardiac monitoring and pulse oximetry.
- Obtain IV access and send routine laboratory studies (see “ ”).
- Plan for early CNS cause is suspected. if
- Obtain collateral history from witnesses
Use to quickly assess and document neurological function at presentation and regularly reassess to detect changes.
Perform the following concurrently with the initial evaluation, based on clinical suspicion:
- Address rapidly-reversible causes, e.g.:
- Initiate protective measures, e.g.:
- Begin time-sensitive management steps: e.g., ,
Next steps 
- Once the patient is stabilized, proceed with a full clinical and diagnostic evaluation.
- See the following management approaches for specific causes and/or manifestations of AMS:
- ” ”
- ” ”
- ” ”
- ” ”
- ” ” and “ ”
- “ ”
Obtain EEG monitoring for patients with suspected .
Critical management steps by cause
Critical causes include potentially rapidly reversible etiologies and conditions that may pose an imminent threat to life.
Critical causes of AMS or coma and their immediate management
|Condition||Suggestive features||Immediate intervention|
|Hypoxic respiratory failure|| |
|Hypercapnic respiratory failure|| |
| || |
|Opioid overdose|| |
|Carbon monoxide poisoning|| |
|Cyanide poisoning|| |
| || |
| || |
| || |
| || |
|Hypertensive encephalopathy|| |
|Imminent brain herniation|| |
Perform diagnostic studies based on clinical evaluation in tandem with the. More thorough targeted diagnostics can be obtained once the patient is stabilized.
Routine laboratory studies 
- CBC: to evaluate for signs of infection, e.g., leukocytosis
- BMP: to evaluate for electrolyte imbalances, acidosis, and renal dysfunction
- Blood gases: to evaluate for hypercarbia, hypoxia, and acid-base imbalances
- Liver chemistries, albumin, INR: if hepatic encephalopathy is suspected
- Blood cultures: if infection is suspected
- Urine analysis: Consider including urine toxicology screen.
- Consider serum drug levels: e.g., acetaminophen, salicylates, ethanol.
ECG findings 
- History of head injury
- Persistent AMS despite treatment or resolution of the suspected cause
- Initial modality: CT head without contrast 
- Advanced imaging: consider based on clinical suspicion
May be indicated based on the clinical presentation and the suspected underlying etiology. For further information, see:
- “ ”
- ” ”
- “ ”
- “ ”
- “ .”
- urinary retention  for
Prevention of coma complications
- Maintenance fluids as needed
- for and medication
- Corneal protective measures for incomplete eyelid closure (e.g., taping, lubricant). 
Prevention of iatrogenic complications
- Other: Initiate discussions of and/or with the , if appropriate.
Depends on the site of initial assessment (e.g., ED vs. ward), clinical stability, expected course, and individual patient factors. 
- Consider ICU admission for patients requiring frequent monitoring, hemodynamic stabilization, and/or respiratory support.
- Consider urgent interfacility transfer for neurosurgical intervention if not available locally.
- Consider discharge home in patients with all of the following:
In patients with altered mental status due to long-acting agents (e.g., opioid overdose from methadone, hypoglycemia from sulfonylureas), consider admission for observation even if the mental status has returned to baseline.
Acute management checklist
- Perform an ABCDE assessment including a rapid neurological assessment (e.g., using GCS, AVPU, FOUR score).
- Identify and treat rapidly reversible .
- Implement immediate protective measures (e.g., definitive airway, C-spine immobilization, neuroprotective measures).
- Perform basic diagnostic studies (e.g., CBC, BMP, toxicology screen, ECG).
- Obtain head imaging (e.g., CT, MRI) if there is a history of head trauma or concern for a structural CNS process.
- Perform further diagnostics (e.g., EEG, LP) based on clinical suspicion.
- Review the patient's medications for possible contributing drugs or withdrawal.
- Treat the underlying cause.
- Start supportive care to prevent the development of complications.
- Consider transfer to the ICU or neurosurgical care unit.
- Monitor with serial GCS or FOUR score assessments.