In medical charts and clinical notes, SI/HI stands for suicidal ideation and homicidal ideation. You will most often encounter this shorthand in psychiatric evaluations, emergency department records, and mental health intake forms, where clinicians use it as quick documentation that a patient was screened for thoughts of self-harm or harm toward others. The abbreviation looks clinical and cold on paper, but what it represents is a routine and important part of how healthcare providers assess safety, and understanding what it means can be genuinely useful if you or someone you care about is navigating mental health treatment.
Where You Will See SI/HI and What It Signals
SI/HI appears constantly in psychiatric documentation. It often shows up in a cluster of abbreviations like “denies SI/HI/AVH,” meaning the patient denies suicidal ideation, homicidal ideation, and audio-visual hallucinations. A study examining how clinical notes use abbreviations in mental health settings found that this particular string was so common that automated text-analysis tools struggled with it, frequently misreading negation phrases like “denies SI/HI/AVH” and incorrectly flagging patients as endorsing those symptoms.1PubMed Central. Symptom-based patient stratification in mental illness using clinical notes That tells you something about how pervasive the shorthand is: it is practically a checkbox phrase in mental health charting.
When a clinician writes “patient endorses SI,” they are noting that the patient acknowledged having thoughts about suicide. “Patient denies HI” means the patient said they are not having thoughts about harming anyone else. These notations don’t, on their own, tell you how severe those thoughts are, how frequent, or whether there is a plan. They are the first layer of screening, not the full picture.
What Suicidal Ideation Actually Means
Suicidal ideation covers a broader range of experiences than most people assume. It does not necessarily mean someone is planning to end their life. The term includes everything from a fleeting wish to not be alive anymore, all the way through to a detailed plan with intent to act on it. Clinicians draw a line between passive and active suicidal ideation, and that distinction matters enormously in determining the level of care someone receives.
Passive suicidal ideation involves thoughts like “I wish I weren’t here” or “I wouldn’t mind if I didn’t wake up tomorrow.” There is no intention or plan to act. Active suicidal ideation, by contrast, involves thoughts about actually killing oneself, potentially including a method or timeline. Research using real-time data collection from individuals experiencing suicidal thoughts found that passive ideation was endorsed far more frequently than active ideation alone. In that study, passive SI showed up by itself in about 38% of recorded observations, while active SI alone appeared in less than 1%. Both types co-occurred in roughly 43% of observations, meaning most people who experienced active thoughts also had passive ones.2PubMed Central. Exploring Predictors of Passive Versus Active Suicidal Ideation: Idiographic Analysis of Real-Time Data The two are closely linked but separable, and for most individuals there was a direct connection where passive thoughts preceded active ones.
This is why clinicians don’t just ask “are you thinking about suicide?” and stop. They probe further. A person who says “I sometimes wish I could go to sleep and not wake up” is in a different clinical situation than someone who says “I’ve been thinking about how I would do it and I have a plan.” Both responses count as suicidal ideation, but they point toward very different levels of risk and very different next steps.
What Homicidal Ideation Means
Homicidal ideation is the counterpart on the HI side: thoughts about killing or seriously harming another person. Like SI, it exists on a spectrum. A passing angry thought about hurting someone during a heated argument is different from a persistent, specific fantasy about harming a named individual. Clinicians screen for HI partly because it can signal psychotic symptoms, intense emotional dysregulation, or the influence of substances, and partly because of their legal and ethical obligations.
In practice, HI is less commonly endorsed than SI, and when patients do report it, the overwhelming majority have no intent or plan. But the screening matters because it shapes what happens next. If a patient expresses credible, specific threats toward an identifiable person, clinicians in many jurisdictions have a legal duty to take protective action, which could include warning the potential victim or notifying law enforcement. This obligation, rooted in landmark legal precedent, means that HI gets documented carefully even when it seems unlikely to lead to action.
One thing worth knowing: endorsing HI does not automatically lead to involuntary commitment or arrest. It triggers a clinical conversation, not a legal one, unless the clinician determines there is genuine, imminent danger to a specific person. Many patients with intrusive violent thoughts, particularly those with obsessive-compulsive disorder, experience HI as deeply distressing and ego-dystonic, meaning the thoughts feel alien and unwanted. In those cases, the appropriate response is treatment for the underlying condition, not a threat assessment.
How Clinicians Measure the Severity of SI
Once someone endorses suicidal ideation, the next question is how serious it is. The most widely used structured tool for this is the Columbia-Suicide Severity Rating Scale, or C-SSRS. It breaks ideation into a five-point scale ranging from a wish to be dead at the low end, through non-specific active thoughts (“Have you actually had any thoughts of killing yourself?”), to thoughts with a method, to intent, and finally to intent with a specific plan.3PubMed Central. Columbia-Suicide Severity Rating Scale Screen Version: initial screening for suicide risk in a psychiatric emergency department The full version of the C-SSRS also includes subscales that assess the intensity of ideation and track actual suicidal behaviors, including past attempts.4PubMed Central. C-SSRS Performance in Emergency Department Patients at High Risk for Suicide
The C-SSRS is used across emergency departments, inpatient units, outpatient clinics, schools, and even in military and correctional settings. Its value lies in giving everyone a shared vocabulary. When one clinician documents that a patient scored a “3” on the ideation severity scale, the next clinician knows exactly what that means: the patient has been thinking about suicide and has thought about a method, but has not expressed intent or made a plan. This kind of standardized rating helps determine whether someone needs inpatient hospitalization, an intensive outpatient program, or can safely be managed with outpatient therapy and a safety plan.
What Triggers Suicidal and Homicidal Ideation
SI and HI are symptoms, not diagnoses. They show up across a wide range of conditions. Depression is the most commonly associated diagnosis for SI, but suicidal thoughts also appear in anxiety disorders, PTSD, substance use disorders, bipolar disorder, schizophrenia, and personality disorders. They can also emerge in people with no psychiatric history at all, particularly during acute crises like job loss, relationship breakdown, or bereavement.
Neurological conditions add another layer. A review of the research found meaningful links between suicidal ideation and behavior and conditions including epilepsy, multiple sclerosis, and amyotrophic lateral sclerosis (ALS).5PubMed Central. Suicidal Behavior and Neurological Illnesses These connections likely involve both the psychological burden of living with a serious neurological disease and direct biological effects on brain circuits involved in mood regulation.
Sometimes medications themselves can trigger or worsen SI. Akathisia, a side effect of certain antipsychotic drugs that causes an intensely distressing inner restlessness, has been linked to suicidal ideation, attempts, and completions. A systematic review noted that mild akathisia can be misdiagnosed as psychotic agitation, leading clinicians to increase the very medication causing the problem. The majority of reported cases involved high-potency first-generation antipsychotics.6PubMed Central. The Relationship Between Antipsychotic-Induced Akathisia and Suicidal Behaviour: A Systematic Review This is a genuinely dangerous clinical trap and one of the reasons careful documentation of SI matters over time: a worsening trend can help clinicians spot a medication side effect before it becomes a crisis.
Safety Planning and What Happens in an Emergency
When someone presents to an emergency department with SI, the clinical response increasingly centers on safety planning. A safety plan is a written, personalized document created collaboratively with the patient. It typically includes warning signs the person can recognize in themselves, coping strategies they can use on their own, people they can contact for support, professionals and crisis lines to reach, and steps to reduce access to lethal means like firearms or stockpiled medications.7PubMed Central. Safety Planning for Youth in the Emergency Department Who Have Suicide Risk
The evidence behind safety planning is solid. A large study comparing safety planning with follow-up phone calls against usual care in emergency departments found that patients who received the intervention were about half as likely to engage in suicidal behavior over the following six months.8PubMed Central. Comparison of the Safety Planning Intervention With Follow-up vs Usual Care of Suicidal Patients Treated in the Emergency Department Another study found that emergency departments that routinely implemented safety planning had lower 30-day readmission rates for suicidal behavior compared to those that did not. The benefit was especially pronounced for patients without recent mental health care, who were about 40% less likely to return to the ED within a month.9PubMed Central. Impact of Emergency Department Safety Planning on 30-Day Mental Health Service Use
For patients who present with acute agitation alongside SI or HI, the immediate priority is de-escalation. Clinical protocols call for verbal de-escalation first, with medications reserved for situations where the patient cannot be safely managed otherwise.10PubMed. An Obstetric and Psychiatric Emergency: Managing Acute Agitation Among Pregnant Patients in the Emergency Department When medication is needed, second-generation antipsychotics like intramuscular olanzapine or ziprasidone tend to take effect within 15 to 30 minutes, while older agents like haloperidol generally take longer.11PubMed. Evidence-Based Review of Pharmacotherapy for Acute Agitation. Part 1: Onset of Efficacy The goal is not sedation for its own sake but calming the patient enough to have a meaningful clinical conversation about what brought them in.
The Dangerous Period After Discharge
One of the most consistently worrying findings in suicide research is how risky the period immediately after hospital discharge is. People who have been hospitalized for psychiatric illness, including those admitted specifically for SI or suicide attempts, face an elevated risk of suicide in the weeks and months after they leave the hospital. Research has found that more intensive follow-up during this immediate post-discharge window is needed to prevent suicide, particularly among patients identified as high-risk during their admission.12PubMed Central. Follow-Up Timing After Discharge and Suicide Risk Among Patients Hospitalized With Psychiatric Illness
Among patients with mood disorders specifically, roughly 40% of suicide reattempts within a year of discharge happened in the first 90 days.13PubMed Central. Incidence and risk factors of suicide reattempts within 1 year after psychiatric hospital discharge in mood disorder patients That concentration of risk so early after leaving the hospital is why bridging appointments, follow-up calls, and safety plans with updated crisis contacts matter so much. If you are supporting someone who has recently been discharged after an SI-related admission, the first three months are the period to be most attentive.
Other Medical Meanings of SI and HI
Context matters with medical abbreviations, and SI/HI does not always mean suicidal ideation and homicidal ideation. In a psychiatric note, that is almost certainly the intended meaning. But in other clinical settings, the same letters can mean entirely different things.
In emergency medicine and trauma care, SI often refers to the shock index, calculated by dividing heart rate by systolic blood pressure. It is a quick bedside tool for identifying patients who may be in or heading toward cardiovascular shock, even when their individual vital signs still look normal.14PubMed Central. Shock index in the emergency department: utility and limitations A normal shock index is roughly 0.5 to 0.7; values above 1.0 are concerning. In an orthopedic chart, SI could refer to the sacroiliac joint. In an endocrinology context, SI might appear in SIADH, the syndrome of inappropriate antidiuretic hormone secretion.
HI, meanwhile, sometimes stands for hearing impairment in audiology and ENT records. Research on hearing loss following head injury, for instance, uses HI in this sense throughout, documenting prevalence and severity of hearing impairment across patients.15PubMed Central. Assessment of Hearing Loss in Minor Head Injury: A Prospective Study In some lab settings, HI might appear in the context of hemagglutination inhibition, an older technique for measuring antibody responses.
If you encounter SI or HI in your medical records and are unsure which meaning applies, the surrounding text usually makes it obvious. Psychiatric intake forms, mental health progress notes, and emergency psychiatric evaluations are the settings where SI/HI means suicidal and homicidal ideation. If the note is discussing vital signs, orthopedic complaints, or hearing tests, you are looking at a different definition entirely.
Reading Your Own Medical Records
With the increasing availability of open notes through patient portals, more people are encountering abbreviations like SI/HI for the first time in their own records. Research on open notes in mental health has found that patients who read their records generally report improved understanding of their care, better recall of what was discussed in sessions, and in many cases greater trust in their providers. But a minority of patients reported feeling worried or judged by how certain things were worded.16PubMed Central. Open Notes in Mental Health: A Scoping Review of Stakeholder Experiences and Implications for Clinical Practice
Seeing “patient denies SI/HI” in your chart might feel strange, but it is actually a good sign: it means your provider asked the screening questions and documented your response. Clinicians are trained to ask about SI and HI routinely, even when there is no reason to suspect either. It is a safety practice, like checking blood pressure at every visit, not a reflection of something specific about you. If the note says “endorses SI” and you want to understand more about what was documented and why, asking your provider directly is the best approach. In that same body of research on open notes, clinicians reported adjusting their language and tone in documentation to reduce the chance of misinterpretation, so your provider is likely already thinking about how their notes read from your perspective.
Cultural Differences in How Suicidal Ideation Is Received
How people respond to someone disclosing suicidal thoughts varies across cultures in ways that can affect whether a person seeks help. An experimental study comparing responses in Korea and Australia found that Australian participants showed notably more concern when a friend expressed suicidal ideation compared to general distress, and were more likely to recommend active coping strategies like talking it through or seeing a doctor. Korean participants, by contrast, did not clearly differentiate between the suicidal and non-suicidal scenarios, and were more likely to suggest passive coping approaches like waiting for time to heal or encouraging the person to cheer up.17PubMed Central. Cultural Differences in Reactions to Suicidal Ideation: A Mixed Methods Comparison of Korea and Australia
This does not mean one cultural response is right and the other wrong, but it does highlight that the same disclosure of SI may receive very different reactions depending on cultural context. For clinicians working with diverse populations, this matters because a patient’s willingness to disclose suicidal thoughts may be shaped by how they expect those thoughts to be received. And for anyone supporting a friend or family member, understanding that “cheer up” or “give it time” may not register as adequate acknowledgment of what the person is trying to communicate is practical knowledge worth having.
Digital Tools and the Future of SI/HI Screening
Screening for SI and HI has historically depended on face-to-face conversation, but digital tools are changing that. A systematic review of digital suicide prevention tools found that artificial intelligence models analyzing social media posts and health data could identify suicide risk with accuracy rates ranging from roughly 72% to 93%.18PubMed Central. Harnessing technology for hope: a systematic review of digital suicide prevention tools These tools are not replacing clinical interviews, but they are being explored as ways to flag risk earlier, particularly for people who might never walk into a clinic or emergency department on their own.
The ethical questions are significant. Passive monitoring of social media raises obvious privacy concerns, and the consequences of false positives (flagging someone as suicidal when they are not) can include unwanted welfare checks, stigma, and erosion of trust. False negatives carry their own risk, obviously. How these tools get integrated into healthcare systems, if they do, will likely be one of the more contentious policy conversations in mental health over the next decade. For now, the standard remains a human clinician asking the questions, documenting the answers using abbreviations like SI/HI, and making judgment calls about the next steps based on the full clinical picture.