A paediatric prescription with a missing allergy entry
A 4-year-old child weighing 14 kg is admitted with pneumonia. The prescription reads: oral amoxicillin 250 mg three times a day for 5 days, plus syrup paracetamol 210 mg when the temperature is above 38 °C. The pharmacy issues a bottle of amoxicillin suspension labelled 125 mg per 5 mL and a bottle of paracetamol suspension labelled 250 mg per 5 mL. There is only one 5 mL teaspoon in the ward. While taking the drug history, the mother says that last year the child's face swelled and he had "big red patches" after a syrup the doctor gave for a throat infection. The prescription sheet has no allergy column filled in. The ward is short of spoons and the tray has unlabelled cups.
1. Calculate the volume of each drug for one dose and show your working.
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Amoxicillin
- Stock: 125 mg in 5 mL.
- Needed: 250 mg.
- 250 ÷ 125 = 2 portions of 5 mL.
- Dose = 10 mL three times a day.
Paracetamol
- Stock: 250 mg in 5 mL.
- Needed: 210 mg.
- 210 ÷ 250 = 0.84; 0.84 × 5 mL = 4.2 mL per dose, only when the temperature is above 38 °C.
Check the dose against body weight - this is the step students skip.
- Amoxicillin: 250 mg ÷ 14 kg ≈ 18 mg/kg/dose. Standard oral paediatric amoxicillin is 15–25 mg/kg/dose three times daily, so the prescribed dose is acceptable.
- Paracetamol: 210 ÷ 14 = 15 mg/kg/dose. Standard is 10–15 mg/kg/dose, maximum 4 doses in 24 hours, so it is at the upper limit - do not give a fifth dose or overlap with another paracetamol product.
Conclusion: 10 mL amoxicillin TDS; 4.2 mL paracetamol, not more than 4 times a day. These are different volumes from the same-sized teaspoon, which is exactly why a spoon is not a safe measure.
2. What is the most important safety problem in this situation, and what will you do before the first dose?
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The problem is an undocumented penicillin allergy, not the arithmetic.
Why the history matters: facial swelling with large red patches after a syrup given for a throat infection is angioedema and urticaria. Sore throat syrups are very often penicillins. A second exposure can produce a faster, worse reaction, including bronchospasm or anaphylaxis. This is a life-threatening risk, not a minor rash.
Actions before giving anything:
- Withhold the amoxicillin. Do not give the drug and then report; the doctor's order is not a licence to give a drug the child has reacted to.
- Tell the doctor and the staff nurse immediately and ask what the child was given last year.
- Get the allergy written in the allergy column, on the front of the case sheet, on the drug chart and on the bottle - in red, in words the mother can read.
- Ask for an alternative antibiotic and a fresh prescription.
- Ask the mother to repeat the story so it is documented in her words.
- Know your emergency plan - where adrenaline is kept, whom to call - before any first dose of a new antibiotic is given.
Do not "try a small dose" to test. That is a dangerous practice outside a controlled setting.
3. How would you measure and give the medicines, and what would you teach the mother before discharge?
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Measuring - accuracy is part of the dose.
- Shake the suspension well; the drug settles at the bottom.
- Use an oral syringe or a proper 5 mL and 10 mL measuring cup, not the single teaspoon. A household teaspoon holds 3–7 mL, so 10 mL could be delivered as 6 mL or 15 mL.
- Measure at eye level on a flat surface; draw 10 mL for amoxicillin and 4.2 mL (about 4 mL) for paracetamol in separate syringes.
- Never use the unlabelled tray cups. Label each bottle with the child's name, drug, dose and time.
- Give amoxicillin three times a day at fixed times, with or without food; give paracetamol only when the temperature is above 38 °C, at least 4 hours apart.
- Stay with the child for a few minutes after the dose; watch for rash, swelling of the lips, noisy breathing or vomiting.
Teach the mother:
- The exact volumes, written down, and that the two bottles are never mixed.
- Complete the full 5 days of the antibiotic even if the child looks well on day 2.
- Paracetamol is not a routine tonic; no more than 4 doses in 24 hours, and not together with any other paracetamol syrup.
- Stop the drug and return at once if the face or lips swell, breathing becomes noisy, or a rash appears.
- Shake the bottle every time; discard after 7 days of opening; keep out of the child's reach.