In this section
For 24 hour advice, contact Victorian Poisons Information Centre 131126
The risk of seizures following overdose with SNRIs is dose dependent. Seizures may be delayed up to 16 hours following overdose, particularly following overdose with extended release preparations
There is a risk of hypotension, prolonged QRS duration and QT interval, and cardiac dysrhythmias with large ingestions.
Also, there is a high risk of
serotonin syndrome if other serotonergic agents are co-ingested.
Patients Requiring Assessment
Dose requiring medical assessment in paediatric accidental ingestions:
*Note these values do not apply to adolescents or adults (please
discuss with toxicologist)
Clarify the drugs ingested (including co-ingestants and formulations)
Ascertain the amounts ingested and when the ingestion occurred
Symptoms usually begin within 4 hours of consumption (may be delayed up to 6-12 hours with extended-release preparations) and usually resolve within 24 hours
SNRIs overdose does not commonly cause coma or significantly reduced level of consciousness and this suggests co-ingestion or an alternate cause.
Seizures are common occurring in up to 14% of patients, with incidence dose dependent.
Hypotension and cardiac dysrhythmias only occur following large ingestions
Although the clinical features may be serotonergic in origin severe
serotonin syndrome only occurs if there is co-ingestion of other serotonergically active drugs (especially MAOIs)
Examination may reveal dysphoria, anxiety, mydriasis, tremor, tachycardia and hypertension
12 lead ECG, blood glucose and paracetamol concentration in deliberate self-poisoning
ECG on presentation and ECG 6hly until discharge
If large ingestion or prolonged QRS or QTc ongoing cardiac monitoring and 2hrly ECG is recommended
Consider Paracetamol level in all intentional overdoses
Standard procedures and supportive care
Early intubation and ventilation is indicated if large ingestion (Discuss with toxicologist)
Activated charcoal should only be administered following discussion with toxicologist but should be considered in alert, co-operative patients who have large ingestions.
Increasing agitation, tachycardia or tremor may herald onset of seizures and can be controlled with titrated doses of intravenous diazepam to achieve light sedation. Treat seizures with benzodiazepines
Avoid phenytoin and fentanyl
2. Cardiac Arrhythmias
Monitoring is required with significant overdose
Hyperthermia is a sign of severe
serotonin syndrome and should be immediately treated. Serotonin syndrome can also be treated with titrated intravenous benzodiazepines (Discuss with
Patients with accidental ingestion can be observed at home if asymptomatic and dose is below that requiring medical assessment
Because of the risk of seizures all patients with deliberate self-poisoning or accidental ingestion requiring assessment should be observed for a minimum of 16 hours and until symptom free
Patients with large ingestions require on-going cardiac monitoring (Discuss with toxicologist)
Consult Contact Victorian Poisons Information Centre 131126 for advice
Patients who have large ingestions or develop severe
serotonin syndrome should be managed in PICU.
For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.
Period of observation (as above)
For deliberate ingestion, a risk assessment should indicate that the patient is at low risk of further self-harm in the discharge setting
Parent information sheet from Victorian Poisons Information centre on the prevention of poisoning
Intentional self –harm: Referral to local mental health services eg Orygen Youth Health: 1800 888 320
Last updated June 2017