Deliberate Self-Harm

Deliberate self-harm (DSH) requires medical stabilisation as the first priority, before any psychosocial assessment. Specific overdose toxidromes (paracetamol, salicylate, TCA) have time-critical antidotes. Psychosocial risk assessment and safe…

NICE NG225 Self-Harm Guideline

The pathway

1 · Medical stabilisation — identify toxidrome

Paracetamol overdose: measure level at 4 hours post-ingestion; use Rumack-Matthew nomogram to determine NAC need. Staggered ingestion or unknown time → treat as high risk
Salicylate overdose: check level; urinary alkalinisation (sodium bicarbonate IV) if level >350mg/L or symptomatic; haemodialysis if level >700mg/L, AKI, or encephalopathy
TCA (tricyclic antidepressant) overdose: sodium bicarbonate 1–2mmol/kg IV if QRS >100ms or ventricular arrhythmia; avoid flumazenil in mixed overdose
Opioid overdose: naloxone 0.4–2mg IV/IM titrated; repeat every 2–3 min (max 10mg); infusion if large ingestion
Benzodiazepine overdose: supportive care, airway protection; flumazenil rarely used (lowers seizure threshold in mixed overdose)

2 · Investigations in all DSH presentations

Paracetamol level (mandatory in all presentations — often co-ingested without disclosure)
Salicylate level
U&E, LFTs (paracetamol hepatotoxicity baseline)
ECG: QRS width (TCAs, antipsychotics), QTc (SSRIs, antipsychotics), QT prolongation
VBG/ABG: pH, lactate, methaemoglobin if indicated
Urine drug screen, ethanol level
Pregnancy test in women of childbearing age
Contact National Poisons Information Service (TOXBASE) for guidance on unusual ingestions

3 · Paracetamol overdose — NAC (N-acetylcysteine)

Measure paracetamol level at 4h post-ingestion — plot on Rumack-Matthew nomogram
NAC regimen: 150mg/kg IV in 200ml 5% glucose over 1h, then 50mg/kg in 500ml over 4h, then 100mg/kg in 1000ml over 16h (total ~21h)
Staggered ingestion: treat if >75mg/kg taken regardless of level
Monitor: LFTs, INR, creatinine, glucose at baseline, 4h, and 21h
NAC side effects: anaphylactoid reaction (slow infusion, treat with antihistamine ± chlorphenamine)

4 · Psychosocial risk assessment

Use Columbia Suicide Severity Rating Scale (C-SSRS) or SADPERSONS as structured tools
Assess: intent at time of act, circumstances (alone vs. witnessed, precautions against discovery), method lethality, ongoing suicidal ideation, mental illness, previous attempts
Protective factors: reasons for living, social support, therapeutic alliance
Every patient seen by mental health liaison before discharge if deliberate intent confirmed

5 · Safe discharge planning

Safety plan documented and given to patient
Next of kin / carer informed (with patient consent)
GP notified same day (electronic or phone)
Crisis line provided: e.g. Samaritans 116 123, local crisis team number
Psychiatric follow-up arranged within 1–2 weeks (or sooner if high risk)
Means restriction counselling: advise removal of medications, firearms, or other methods from home

6 · MHA if high risk and refusing admission

If patient has active suicidal ideation with plan and intent and refuses voluntary admission:
Section 2 MHA (assessment up to 28 days) if acute mental disorder
Requires AMHP + 2 doctors (one Section 12 approved)
Section 5(2): if already an inpatient and needs detaining — doctor's holding power up to 72 hours
Document risk clearly in notes to justify MHA use

7 · Safeguarding considerations

Under 18: safeguarding referral mandatory; involve CAMHS and paediatric team; inform parents/guardians unless doing so increases risk
Domestic abuse as precipitant: IDVA referral, safety planning
Elderly or vulnerable adult: consider Adult Safeguarding referral if neglect, abuse, or coercion involved
All DSH admissions: complete safeguarding documentation per local trust policy

Drugs

Drug	Dose	Route	Notes
N-acetylcysteine (NAC)	150mg/kg over 1h → 50mg/kg over 4h → 100mg/kg over 16h	IV	Paracetamol antidote. Plot 4h level on Rumack-Matthew nomogram. Treat staggered overdose regardless of level. Anaphylactoid reaction in ~15% — slow infusion, treat with chlorphenamine 10mg IV.
Sodium bicarbonate 8.4%	1–2 mmol/kg IV bolus	IV	TCA overdose with QRS >100ms or ventricular arrhythmia. Also for salicylate urinary alkalinisation (target urine pH 7.5–8.5). Repeat as needed guided by arterial pH.
Naloxone	0.4–2mg, repeat every 2–3 min (max 10mg)	IV or IM	Opioid reversal. Short half-life — may need infusion (2/3 of effective bolus dose per hour) for long-acting opioids.
Activated charcoal	50g	PO	Within 1 hour of significant ingestion if airway protected and not vomiting. Do not give if corrosive or hydrocarbon ingestion.
Chlorphenamine	10mg	IV	For NAC anaphylactoid reaction — give slow IV if urticaria, flushing, or bronchospasm during NAC infusion. Pause NAC, treat, then restart at lower rate.

When to escalate

Paracetamol-induced acute liver failure (INR >2, encephalopathy, creatinine rising) — urgent liver unit referral for possible transplant assessment,Salicylate level >700mg/L or encephalopathy/AKI — urgent haemodialysis,TCA overdose with QRS >160ms or haemodynamic instability — ITU, sodium bicarbonate, consider intubation,Active suicidal ideation with plan and intent refusing admission — MHA assessment immediately,Under-18 with serious self-harm — CAMHS and safeguarding referral, do not discharge without senior review,Altered GCS or airway compromise from overdose — anaesthetics for intubation, ICU referral

Reference: NICE NG225 Self-Harm: Assessment, Management and Preventing Recurrence 2022

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