One Pill Killers

Toddlers are a distinct species within paediatrics. Take the stubbornness of a goat, the morals of a used-car salesman, the dexterity of a plastic surgeon and the temperament of Bruce Banner – and you end up with what is basically a tiny, intellectually challenged ninja, with the capacity to do alarmingly stupid things with incredible speed and skill.

Chugging a whole bottle of calpol. Pushing a chair onto baby sister’s head. Irretrievably shoving a bean up a nostril/both nostrils (all true stories).

Many trips to ED happen as a result of toddler misadventure, but few are life threatening. That’s why this post is about what CAN potentially kill a toddler – the contents of Granny’s handbag. There are several common medications – used mostly in elderly patients – that contain a high enough dose in one or two tablets to do serious harm (or worse) to a small child.

I’m not going to run through the details of all the toxicology and treatments. This aim of this post is to highlight some drugs that should have alarm bells ringing at triage, and get you running over to the child who is about to become the sickest kid in the department.

When considering the toxic doses of the drugs mentioned below, keep in mind that an average toddler weighs 10-15kg.

What’s in Grandma’s handbag?


  • Cardiac drugs

Calcium channel blockers (nifedipine, verapamil, amlodipine, diltiazem) – these are used therapeutically as antihypertensives and antiarrhythmics. In toxicity, they cause hypotension, bradycardia and cardiac arrest. A dose as low as 0.2mg/kg (depending on drug) could be lethal.

Clonidine – sometimes used as an antihypertensive (also can be used to treat menopausal symptoms and migraine)

Tablet doses available Toxic dose per kg
Amlodipine 5mg, 10mg  0.2mg/kg
Nifedipine 5mg, 10mg; sustained release up to 60mg.  1.2mg/kg
Verapamil 5mg, 10mg  5mg/kg
Diltiazem 60mg; sustained release tablets up to 360mg.  5mg/kg
Clonidine 0.025mg, 0.1mg 0.01mg/kg

LET ME REPEAT THAT WEIGHT… the average toddler weighs 10-15kg.


  • Antidiabetics

Sulphonylureas (gliclazide) – stimulates insulin release from beta cells, causes hypoglycaemia in non-diabetics.

Tablet doses available Toxic dose per kg
Gliclazide 40mg, 80mg; sustained release up to 60mg. 1.3mg/kg

AGAIN, the average toddler weighs 10-15 KILOGRAMS.


  • Antidepressants

Tricyclic antidepressants, or TCAs (amitryptyline, imipramine). Blockade of sodium channels, muscarinic (M1), histaminergic (H1), and peripheral alpha1-adrenergic receptors. Effects include tachycardia, dry mouth, urinary retention, confusion, agitation… leading on to hypotension, arrythmias, and seizures.

Benzodiazepines (diazepam, temazepam, etc) – cause respiratory depression.

Tablet doses available Toxic dose per kg
Amitryptiline 10 mg, 25 mg, 50 mg 15mg/kg
Diazepam 2mg, 5mg, 10mg 0.7mg/kg
Temazepam 10mg, 20mg 1.5mg/kg
  • Parkinsons drugs

Selegiline – a monoamine oxidase inhibitor (MAOI) which in overdose causes hypertension, tachycardia, tremors, seizures, and hyperthermia.

Tablet doses available Toxic dose per kg
Selegiline 5mg, 10mg 0.7mg/kg

One last time: an average toddler weighs 10-15kg. Any of the drugs listed above have a SERIOUS RISK of causing significant harm or worse to a tiny human. Commit these drugs to memory, and get ready to move if you hear the word.

Disclaimer: This is NOT a comprehensive list of all potentially fatal one-dose drugs. Always check your local toxicology protocols.

Drug doses and toxic doses from

With thanks to Dr Lara Ziebers, whose excellent talk this post is based on.

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