Common Registration Assessment, Part 1
Adult paracetamol and the daily maximum
Three original questions on adult paracetamol totals and the daily maximum, using the NHS dosing page.
Published 13 October 2026. Independent revision material, not GPhC questions, not for patient care.
For 500 mg tablets the NHS says one dose is 1 or 2 tablets, with at least 4 hours between doses and no more than 8 tablets in 24 hours. For 1 g tablets it is one at a time and no more than 4 in 24 hours.
The liquid comes as 250 mg in 5 mL or 500 mg in 5 mL, with no more than 4 doses in 24 hours. The page also warns against taking other medicines that contain paracetamol at the same time.
The method
- Convert each product to mg of paracetamol.
- Multiply the dose by the number of doses to find the total.
- Add paracetamol from every product taken in the same 24 hours.
- Compare with the daily limit: 8 tablets of 500 mg, which is 4,000 mg.
- Subtract the total taken so far to find what remains.
Three practice questions
Work each one on paper first, then open the answer. All patients and prescriptions are fictional.
Question 1
How many mg is 8 tablets of 500 mg, and how many 2-tablet doses can be taken in 24 hours?
Show the answer
Answer: 4,000 mg, and 4 doses
Working: 8 × 500 = 4,000 mg. 8 ÷ 2 = 4 doses.
Question 2
A patient takes 2 × 500 mg tablets at 08:00, 12:00 and 16:00, then a cold remedy at 20:00 that contains 500 mg of paracetamol. What is the total in mg, and how many 500 mg tablets are left before 4,000 mg?
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Answer: 3,500 mg, and 1 tablet
Working: Tablets: 2 × 3 = 6 tablets = 3,000 mg. Add 500 mg = 3,500 mg. 4,000 - 3,500 = 500 mg, which is 1 tablet.
Question 3
An adult uses 500 mg in 5 mL liquid, 10 mL a dose. How many mg is one dose, and how many mL and mg in the maximum 4 doses?
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Answer: 1,000 mg a dose, and 40 mL which is 4,000 mg
Working: 500 ÷ 5 = 100 mg per mL. 100 × 10 = 1,000 mg. 10 × 4 = 40 mL, and 1,000 × 4 = 4,000 mg.
Exam approach
Convert every product to mg and add. A running total makes the remaining allowance obvious.
Where marks are lost
- Leaving out paracetamol that is in a cold or flu product.
- Counting tablets instead of mg when strengths differ.
- Mixing up the 500 mg per 5 mL and the 250 mg per 5 mL liquids.
- Forgetting that the NHS page says a lower dose may be needed under 50 kg.
Frequently asked questions
How long can paracetamol be taken for?
The NHS page says not to take or use it for more than 3 days unless a doctor says so.
Does weight matter?
The NHS page says someone weighing less than 50 kg may need a lower dose, and to check the packet or ask a pharmacist.
Sources
- NHS, how and when to take paracetamol for adults
- GPhC, Common Registration Assessment specification and permitted items for 2026
The questions above are original and use fictional patients and prescriptions. PreRegExamPrep is not affiliated with or endorsed by the General Pharmaceutical Council.
Practise until the method is automatic
Try 15 free questions with worked answers. No sign-up required.
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See also the formula sheet, the eight sample questions and the approved calculator page.