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Pharmacy & Pharmacology vocabulary · Prescriptions and Dosing

As needed

Meaning in pharmacy & pharmacology, with examples

phraseCore term

In pharmacy & pharmacology, as needed means: An instruction meaning that a medicine is taken only when the patient has the symptom it treats, such as pain or breathlessness, not at fixed times.

In Turkish: gerektiğinde, ihtiyaç halinde, lüzumu halinde

How it is used

Written PRN on charts and prescriptions, from the Latin 'pro re nata'. A clear instruction also states the reason and a maximum, such as 'as needed for pain, up to four times a day'. UK patients may also hear 'when required'. Pharmacists check how often patients actually use their as-needed medicines.

Example sentences

  1. She uses her blue inhaler as needed, about twice a week.

  2. The paracetamol is prescribed as needed, so check when she last had a dose.

Common collocations

  • take as needed
  • as-needed medication
  • PRN dose
  • when required
  • dosageHow much of a medicine to take, how often and for how long, for example two tablets three times a day for five days.
  • twice dailyTwo times a day, usually about twelve hours apart, such as morning and evening; one of the most common directions on prescriptions and labels.
  • prescriptionA written or electronic order from a doctor or other authorised prescriber that tells the pharmacist which medicine to supply and how the patient should use it.
  • analgesicA medicine that relieves pain without making the patient unconscious, from simple products such as paracetamol to strong opioids such as morphine.

More terms: Prescriptions and Dosing

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This page explains English vocabulary for learners. It is not medical advice.