Common Registration Assessment, Part 1
Peppermint oil capsules daily doses and timing for the GPhC assessment
Three original practice questions, with the working shown. Read the stated prescription or plan before calculating.
Published 30 October 2026. Independent revision material, not GPhC questions, not for patient care.
The NHS lists the usual dose of peppermint oil capsules for adults and children aged 12 years and over as 1 capsule taken 3 times a day until symptoms improve, increasing to 2 capsules taken 3 times a day if 1 capsule does not help.
The NHS advises taking the capsules around 30 to 60 minutes before food, swallowing them whole with water, and leaving a gap of at least 2 hours between a dose of peppermint oil and an indigestion medicine.
The NHS advises that if you buy peppermint oil from a pharmacy or shop, you should not take it for longer than 2 weeks without speaking to a doctor.
Each question fixes the values needed for its arithmetic. Write the unit beside every step and distinguish a single dose from a daily total or course supply. All prescriptions and patients here are fictional; these are revision materials, not for patient care.
The method
- Identify the stated dose per occasion (1 or 2 capsules) and the daily frequency.
- Calculate one day first: capsules per occasion times occasions per day.
- Scale to the stated duration, keeping within any stated limit such as 2 weeks for over-the-counter use.
- For timing questions, add the stated gap to the stated dose time before answering.
- Keep capsule counts and time intervals as separate units.
Three practice questions
Work each one on paper first, then open the answer. All patients and prescriptions are fictional.
Question 1
A fictional patient takes 1 peppermint oil capsule 3 times a day for 14 days. How many capsules is that?
Show the answer
Answer: 42 capsules
Working: 1 capsule x 3 times a day = 3 capsules a day; 3 x 14 days = 42 capsules.
Question 2
A fictional patient takes 2 capsules 3 times a day. A pack contains 84 capsules. How many days will the pack last?
Show the answer
Answer: 14 days
Working: 2 capsules x 3 times a day = 6 capsules a day; 84 capsules / 6 capsules = 14 days.
Question 3
A fictional patient takes a peppermint oil capsule at 8am. An indigestion medicine is needed the same morning. Using the stated minimum gap, what is the earliest time for the indigestion medicine?
Show the answer
Answer: 10am
Working: Stated minimum gap is 2 hours; 8am + 2 hours = 10am.
NHS: How and when to take peppermint oil
https://www.nhs.uk/medicines/peppermint-oil/how-and-when-to-take-peppermint-oil/
Where marks are lost
- Counting occasions instead of capsules when the dose is 2 capsules at a time.
- Ignoring the stated 2-hour gap in timing questions.
- Treating arithmetic as evidence that longer use is suitable; over-the-counter use beyond 2 weeks needs a doctor's advice.
Frequently asked questions
Are these official assessment questions?
No. They are original revision exercises, not official GPhC questions and not for patient care.
Can a supply calculation extend the course beyond 2 weeks?
Not for a bought product. The NHS says to speak to a doctor if symptoms continue beyond 2 weeks; prescribed courses follow the prescriber's instructions.
How should I check the answer?
Check the requested unit, then work backwards from the quantity to the stated dose and duration.
Sources
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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