In healthcare documentation, accurate coding is crucial—not just for billing, but for ensuring clear communication between healthcare professionals and proper care for patients. One code in the ICD‑10‑CM system that often causes confusion is the one for altered mental status. In this article, we will explore what “altered mental status” means, the specific code to use, how to apply it correctly, and pitfalls to avoid. We’ll provide easy-to-understand language and break it into sections so you can follow clearly.
What is Altered Mental Status?
Altered mental status (AMS) is a broad term that refers to any change from a person’s normal level of awareness, cognition, behaviour, or orientation. It can show up in different ways: the person may be confused, disoriented to time or place, less responsive, more agitated, unable to focus, or having trouble understanding or communicating. Because the term is so broad, it isn’t itself a definitive diagnosis—it is a symptom (or set of symptoms) that usually prompt further investigation into the underlying cause.
Here are key points about AMS:
- Changes in cognition: Forgetfulness, inability to follow directions, or thinking that is slower than normal.
- Changes in consciousness or awareness: The person may be drowsy, more sleepy than normal, not fully alert, or conversely overly agitated.
- Disorientation: They might not know where they are, what time it is, or might mix up familiar people/situations.
- Behavioural changes: Sudden agitation, withdrawal, unusual responses, or someone who simply “isn’t themselves”.
- Multiple possible causes: From metabolic issues (like low blood sugar) to infection, head injury, intoxication, drug reactions, or psychiatric issues.
Because many underlying conditions can cause AMS—and because it is a sign rather than a formal diagnosis—it often gets coded as a “symptom” code when the cause is not yet determined. For example, if a patient presents with confusion and disorientation but no clear diagnosis yet, a coder may select a code indicating altered mental status or a similar symptom. Later, when a specific cause is found (such as meningitis or drug toxicity), that diagnosis may replace the symptom code.
The Official ICD-10 Code for Altered Mental Status
The main code used when a patient presents with altered mental status and no specific underlying cause is identified in the record is: R41.82 – “Altered mental status, unspecified.”
Here’s a breakdown of that code:
- It lives in Chapter 18 (R00–R99) of ICD-10-CM: “Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.”
- Within Chapter 18 it is in the block R40–R46: “Symptoms and signs involving cognition, perception, emotional state and behaviour.”
- Specifically, R41- Other symptoms and signs involving cognitive functions and awareness: R41.82 = Altered mental status, unspecified.
It’s important to note that this code is used when the mental status change is present, but a more specific diagnosis has not yet been determined or documented. Once a specific cause is found (for example, delirium due to infection, toxic encephalopathy, head trauma, etc.), the coding should shift to that cause rather than keep using this symptom code.
When To Use R41.82 (Altered Mental Status)
Understanding when it is appropriate to use R41.82 is key—wrong usage can lead to coding errors, reimbursement issues, or miscommunication in clinical records. Here are the conditions under which you may use this code:
Appropriate usage
- The patient presents with noticeable change in mental status (confusion, disorientation, decreased responsiveness, etc).
- No documented cause yet in the medical record. In other words, the clinician has not yet determined or documented a specific diagnosis causing the mental status change.
- The change is not better described by another code (for example, if the patient has documented delirium, encephalopathy or a known cause, those codes are used instead).
Documentation needed
- Clearly record the altered mental status: for example “patient is confused and disoriented to place and time”.
- Note relevant findings (such as labs, imaging, vital signs) if present, even if they do not yet pin a diagnosis.
- If the clinician states “altered mental status, unspecified” or “confusion, etiology unclear” then R41.82 is justifiable.
- Document intention for further work-up (if applicable) such as labs, imaging, or consultation.
When not to use R41.82
- If you have a confirmed cause of the alteration (for instance: “delirium due to urinary tract infection”, “toxic encephalopathy from drug overdose”, “stroke with confusion”): then code the underlying cause rather than just “altered mental status”.
- If the presentation is more specifically described by a more specific code (e.g., delirium NOS (R41.0) or altered level of consciousness (R40.x)) then use that code.
- If the change is very transient or minor and not documented as “altered mental status,” then R41.82 may not be appropriate.
🧠 ICD-10 Codes Related to Altered Mental Status
| Code | Description | When to Use | Exclusions / Notes |
|---|---|---|---|
| R41.82 | Altered mental status, unspecified | Use when a patient presents with confusion, disorientation, or change in awareness without a clear cause identified. | Do not use if the cause (e.g., delirium, encephalopathy, infection, etc.) is known. |
| R41.0 | Delirium, not due to alcohol and other psychoactive substances | Use when the clinician documents delirium (acute onset, fluctuating course, inattention) and it’s not drug-related. | Replace R41.82 once delirium is diagnosed. |
| R41.81 | Age-related cognitive decline | Use when the mental status change is due to ageing or dementia progression rather than acute confusion. | Excludes acute conditions like delirium or toxic encephalopathy. |
| R41.84 | Other specified cognitive deficit | For specific documented cognitive changes like impaired concentration, short-term memory loss, or reduced attention span. | Requires documentation of the specific deficit. |
| R40.0–R40.4 | Altered level of consciousness | Use for patients with reduced alertness, stupor, or coma rather than confusion or awareness changes. | Don’t use for cognitive or behavioural changes. |
| G93.40 | Encephalopathy, unspecified | When altered mental status is due to brain dysfunction of unclear cause (after work-up). | Use a more specific encephalopathy code (toxic, metabolic, hepatic) if identified. |
| G93.49 | Other encephalopathy | For documented specific encephalopathy types (e.g., metabolic, anoxic). | Requires documentation of “encephalopathy.” |
| F05 | Delirium due to known physiological condition | If delirium is linked to a medical condition (infection, metabolic imbalance, etc.). | Often co-coded with the underlying condition (e.g., UTI). |
| F10.231 / F10.121 | Alcohol withdrawal delirium / intoxication delirium | Use when altered mental status results from alcohol or substance withdrawal/intoxication. | Code by substance and severity. |
| R41.9 | Unspecified symptoms and signs involving cognitive functions and awareness | When the record indicates mental status changes but not clearly defined as confusion or delirium. | Least specific—use only when details are minimal. |
⚙️ Quick Coding Guidance
- Start with R41.82 if the cause of confusion is unknown.
- Update to a more specific diagnosis once identified (e.g., delirium, encephalopathy).
- Avoid duplicates—don’t list both R41.82 and a definitive diagnosis unless clearly justified.
- Document precisely: mental status description, duration, suspected causes, and physician assessment.
Why Proper Coding of Altered Mental Status Matters?
Using the correct ICD-10 code for altered mental status has implications beyond simply filling out forms. Here’s why it matters:
Clinical communication and continuity of care
- A proper code ensures that downstream healthcare providers (physicians, nurses, coders) understand that the patient had a cognitive or awareness change, and that further investigation was required.
- It helps in tracking outcomes and follow-up: if a patient was coded with altered mental status, the receiving team knows that they should ask “what was the cause?” and check whether the underlying condition has been identified.
Quality of documentation and coding audits
- Coding accuracy is often audited. Incorrect use of symptom codes when a diagnosis is known (or vice versa) can lead to coding errors, compliance risks, or even claim denials.
- Good documentation supports the code: if you use R41.82, the chart should reflect the confusion, disorientation or change in mental status, plus that the cause was not known or documented at that time.
Reimbursement and healthcare analytics
- The code R41.82 may influence how payers view the encounter (emergency vs routine vs follow-up). Some systems may require more specificity to support certain levels of reimbursement.
- From an analytics perspective, tracking patients who present with “altered mental status” as a symptom helps health systems identify patterns, high-risk patients, or underlying system issues (e.g., frequent metabolic derangements, drug interactions, etc).
Patient safety and clinical follow-up
- If a patient is coded with AMS and the cause is not immediately identified, that flags a “red flag” in care. It suggests we must watch for deterioration, conduct appropriate work-up, and ensure that a cause is found—or that the patient is monitored until mental status returns to baseline.
- Mistakenly using a vague symptom code when a cause is known might hide the underlying condition and delay essential treatment.
Common Causes of Altered Mental Status
Because “altered mental status” is a broad descriptive term, it can be triggered by many underlying conditions. Recognizing common causes is helpful so that appropriate coding can follow once the cause is identified. Here are some frequent reasons for AMS:
- Metabolic derangements: hypoglycaemia or hyperglycaemia (diabetic ketoacidosis), electrolyte imbalances (e.g., hyponatraemia), hepatic or renal failure.
- Infection: urinary tract infections (especially in elderly), sepsis, meningitis/encephalitis, pneumonia with hypoxia.
- Neurologic causes: stroke, transient ischaemic attack, intracranial bleeding, head injury/concussion, seizure post-ictal state.
- Drug or toxin-related: intoxication (alcohol, sedatives, illicit drugs), drug interactions, withdrawal states (alcohol withdrawal delirium), adverse medication effects.
- Hypoxia or poor perfusion: heart failure, respiratory failure, shock, pulmonary embolism.
- Psychiatric/behavioural causes: delirium (which itself may be from multiple causes), severe psychiatric disorders with confusion or disorientation.
- Other acute conditions: dehydration, high fever, extreme pain, severe sleep deprivation, high altitude cerebral edema.
Because the cause list is so long, often at presentation the cause is not yet established. That’s why the symptom code like R41.82 is used initially—but the aim is to find the cause, document it, and code it.
How to Document & Code Properly: Best Practices?
Good documentation supports proper coding. Below are best practice tips to ensure your use of R41.82 (or other related codes) is appropriate and defensible.
Documentation checklist
- Clearly state the patient’s mental status: e.g., “Patient appears confused, disoriented to time and place, cannot reliably answer orientation questions.”
- Indicate any changes from baseline, especially useful if the patient’s baseline is known: e.g., “Patient’s usual cognition is intact; today he is agitated and not responding coherently.”
- Note possible contributing factors or initial investigations: e.g., “Labs drawn: glucose, electrolytes, BUN/creatinine; imaging pending; clinical suspicion for metabolic cause.”
- State whether the cause is known or unknown: if unknown, then a symptom code is appropriate; if known, then code the cause.
- Document any plan for further work-up or monitoring, e.g., “Will evaluate for UTI, check ABG for hypoxia, review medications for sedative effects.”
Coding workflow
- At presentation, if the cause is not yet known, use R41.82 (altered mental status, unspecified).
- Once work-up reveals a cause (e.g., delirium due to urinary tract infection, toxic encephalopathy, stroke) document that clearly and update the coding to the specific code.
- Avoid layering the symptom code AND the definitive diagnosis code for the same encounter unless there is a good reason (documentation should support any combination).
- If the mental status change is described but is actually “altered level of consciousness” (e.g., fainting, loss of consciousness) then use the R40 codes rather than R41.82. Valant+1
- Be aware of payer/insurer requirements: they may prefer more specific diagnostic codes rather than non-specific symptom codes for certain reimbursement tiers. Good documentation helps support your choice.
Pitfalls to avoid
- Using R41.82 when the cause is known and documented (e.g., “delirium due to sepsis” should use the sepsis code + delirium code rather than generic AMS).
- Failing to document the altered mental status or baseline so that the coder cannot justify the code.
- Confusing “altered mental status” with other states like “altered level of consciousness” or “coma” without verifying which is correct.
- Leaving the code unchanged after a diagnosis is found; this can skew analytics and reduce clarity for future providers.
Related Codes and When They Apply
Because “altered mental status” is a generic description, there are multiple related codes which may be more appropriate depending on the clinical situation. Understanding them helps pick the correct code.
Some related codes:
- R41.0 “Delirium, not due to drugs or alcohol” – Use when the patient meets the clinical criteria for delirium (acute onset, fluctuating course, inattention) and documentation supports that.
- R40.4 “Transient alteration of awareness” – Applies when there is a brief alteration in awareness, such as fainting or altered consciousness for a short time.
- R41.9 “Unspecified symptoms and signs involving cognitive functions and awareness” – A fallback code when documentation is even less specific.
- Specific cause codes: If the physician documents “encephalopathy toxic”, “septic encephalopathy”, “liver failure with encephalopathy”, etc., then those codes should be used instead of a generic AMS code.
- Codes for “age-related cognitive decline” (R41.81) or “other specified cognitive deficit” (R41.84) if those apply, rather than generic altered mental status.
Why this matters
By choosing the most specific code that is supported by the documentation, you enhance accuracy, support quality reporting, and improve patient care continuity. Using a more specific code when appropriate also avoids over-reliance on “symptom” codes (which can obscure the underlying pathology).
Steps After Using the AMS Code: What to Do Next
Using R41.82 is often just the first step. Given that altered mental status is a symptom with many possible causes, here’s what teams typically do next:
- Immediate assessment: Evaluate for life-threatening causes (hypoxia, severe hypoglycaemia/hyperglycaemia, stroke, sepsis, toxic ingestion).
- Document baseline and changes: Ask about baseline mental state, any recent changes, medication history, substance use, recent infections, trauma, etc.
- Investigations: Order labs (glucose, electrolytes, BUN/creatinine, liver enzymes, infection markers), imaging (CT/MRI head if indicated), toxicology screen if suspicion of ingestion, and other relevant tests.
- Monitoring and supportive care: Until cause is identified, patient may need close monitoring, possible hospital admission, support for airway/respiration, fluid/electrolyte balance, treating confusion & agitation.
- Once cause identified: Review the diagnosis, document it clearly (e.g., “delirium due to urinary tract infection”), then update coding to reflect the cause—and remove or adjust the generic AMS code if appropriate.
- Follow-up and discharge planning: Ensure cause is resolved or addressed, mental status returns to baseline or improved, and ensure documentation includes outcome and further follow‐up needs.
By following these steps, the use of R41.82 becomes part of a broader process: it communicates “there is a significant cognitive/awareness change here” and prompts the healthcare team to investigate and treat.
Practical Examples: How Coding Might Look
Here are a few examples to illustrate how documentation and coding might differ depending on situation:
Example 1: Initial presentation with unknown cause
Patient arrives confused, disoriented, no obvious cause yet.
- Documentation: “Patient disoriented to time and place, confusion noted, baseline cognitive status unknown, labs drawn, imaging pending.”
- Code: Use R41.82 for altered mental status, unspecified.
- Later: If labs show severe hyponatraemia causing confusion, and physician documents “confusion due to hyponatraemia”, then code for hyponatraemia + the confusion cause rather than generic AMS.
Example 2: Known cause documented
Patient has urinary tract infection, becomes acutely confused.
- Documentation: “Acute onset confusion consistent with delirium secondary to UTI (positive culture).”
- Code: Use code for delirium (R41.0) and underlying infection (urinary tract infection code). Do not use R41.82 as main code because cause is documented.
- Why: Because the underlying cause is known and documented.
Example 3: Altered level of consciousness rather than AMS
Patient fainted, brief loss of consciousness, now regained.
- Documentation: “Patient had a brief syncope episode, regained consciousness; seems to be alert now.”
- Code: Use R40.x code (for altered level of consciousness) rather than R41.82.
- Reason: The change here is level of consciousness (syncope), not broader cognitive/awareness change.
These examples demonstrate how the same “confusion/disorientation” presentation could be coded differently depending on cause and documentation.
Common Mistakes and How to Avoid Them
Even experienced clinicians and coders sometimes make mistakes when coding altered mental status. Knowing what to watch out for helps avoid errors.
Mistake: Using R41.82 when the cause is already known
If the physician documents “altered mental status due to hepatic encephalopathy” then the correct code is the hepatic encephalopathy code—not the generic AMS code.
Fix: Always check whether the cause is documented. If so, code the cause. If not, AMS may be appropriate.
Mistake: Failing to document the mental status change clearly
If the chart just says “patient not himself” or “altered” without describing the nature of the change (confusion, disorientation, etc), the coder may not have enough to support R41.82.
Fix: Document what exactly changed (confusion, memory issue, disorientation), and baseline if known.
Mistake: Confusing AMS with other codes like altered level of consciousness, coma, or delirium
Because there are overlapping terms (confusion, disorientation, stupor, coma), mis‐classification is common.
Fix: Understand the definitions:
- Altered mental status = general cognitive/awareness change.
- Altered level of consciousness = reduced responsiveness, possible loss of consciousness (R40.x).
- Delirium = acute onset, fluctuating, inattention (R41.0).
- Coma = deeper level, unresponsive (other codes).
Mistake: Not updating the code after cause is found
If the chart was initially coded with R41.82 but later the cause becomes documented and the coding remained unchanged, your records may misrepresent the patient’s actual diagnosis.
Fix: Review charts and coding when cause becomes known; ensure updates happen.
Summary: Key Takeaways
- The code for altered mental status, unspecified is R41.82 in ICD-10.
- It is used when a patient has a change in cognitive status or awareness, and the cause is not clearly documented.
- If the underlying cause is known and documented, you should code the cause (and possibly a related symptom/delirium code) rather than R41.82.
- Proper documentation is vital: describe the nature of the mental status change, the baseline, and what is unknown.
- Coding accurately supports clinical care, reimbursement, quality tracking, and patient safety.
- Be aware of related codes (delirium, altered level of consciousness, encephalopathy) and choose the most specific supported by documentation.
- Use R41.82 as a step in the diagnostic process; don’t treat it as a final diagnosis if a cause is found.
Conclusion
Coding for altered mental status may seem straightforward — one code, one label. But in practice, it requires thoughtful documentation, good clinical reasoning, and awareness of when a symptom changes into a specific diagnosis. By using R41.82 appropriately, you’re signaling that an important cognitive change has occurred and that further investigation is warranted. Over time, the goal is to uncover the cause, document it, and update the code so the patient’s record reflects the true diagnosis and supports their care.
