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General prescribing guidance

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find one of our health articles more useful.

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When prescribing, there are a number of points to take into account. Many doctors do this automatically but this article will provide you with some pointers and reminders to bear in mind when prescribing.

Hippocrates' advice 'primum non nocere' - First, do no harm - still holds today. Prescribe only where necessary, and consider benefits versus risks. Involve the patient in decisions about their care and respect patient autonomy.

Note the patient's age, medical history (especially of any hepatic or renal dysfunction) and any concurrent medication. Think about dosage carefully; manufacturers' recommended doses are based on population studies and assume 'one dose fits all'. However, there are genetic differences. New drugs are often marketed at the highest therapeutic level to demonstrate effectiveness in large numbers of patients but companies are not required to provide data on lowest effective dose.

If this is a new - potentially long-term - prescription, review the patient to assess for effect, side-effects and the need to continue.

Safe prescribing

This is becoming an important issue, as evidenced by its increasing prominence in the undergraduate medical syllabus. Issues which need to be considered include:1

  • Prescribing within limits of competence.

  • Evidence-based prescribing.

  • Interaction with other drugs.

  • Concordance, tolerability and formulation.

  • Adverse effects.

  • Checking dosages.

  • Using prescribing formularies.

  • Keeping up to date and following clinical guidelines, where available, from the National Institute for Health and Care Excellence (NICE) or Scottish Intercollegiate Guidelines Network (SIGN).

  • Using electronic systems where available that can enhance the safety of prescribing.

  • Responsible delegation of prescribing administration and dispensing.

Prescribing guidance

Writing prescriptions

Many prescriptions are now computer-produced but, if you are writing one by hand, write legibly in indelible ink, date the prescription and state the full name and address of the patient. All prescriptions should be signed by the prescriber. It is a legal requirement in the case of prescription-only medicines to state the age for children under 12 years, but it is good practice to do so in all cases. Other things to take care of include:

  • Write generics unless there are bioavailability issues, as this will enable the pharmacist to dispense any suitable preparation, avoiding expense and delay.

  • Avoid unnecessary use of decimal points (eg, 3 mg, not 3.0 mg). For quantities less than 1 gram, write in milligrams (eg, 500 mg, not 0.5 g). For quantities less than 1 milligram, write in micrograms (eg, 100 micrograms, not 0.1 mg). Don't abbreviate micrograms, nanograms or units. Use millilitres (ml or mL) not cubic centimetres or cc.

  • Schedules should be written in English, without abbreviation but some Latin abbreviations are acceptable. The British National Formulary (BNF) lists these in full, but common ones in use include:

    • stat = immediately.

    • p.r.n. = pro re nata = when required.

    • o.d. = omni die = every day.

    • o.n. = omni nocte = every night.

    • b.d. = bis die = twice daily.

    • t.d.s. = ter die sumendum = to be taken three times daily.

    • q.d.s. = quater die sumendum = to be taken four times daily.

  • State minimum dose interval and maximum total amount when prescribing p.r.n items.

  • The 'number of days of treatment' box can be used on NHS forms.

  • Specify the strength and quantity. In the absence of this information the pharmacist will attempt to contact you. If unable to do so, they can use their discretion and professional judgement to dispense up to five days' worth of treatment or appropriate amounts of combination packs or oral contraceptives. If they have insufficient information to make a judgement, they will return the prescription to you.

  • Write on the prescription in inverted commas anything other than the name, strength and dosage of the tablets that you want to appear on the label - eg, 'Sedative Tablets'.

  • Avoid abbreviations of drug names and preparations as these can be misinterpreted - eg, Mist.Expect. Don't invent compound generic names, especially for sustained-release preparations.

Computer-issued prescriptions

Recommendations include:

  • Minimum data requirements:

    • Date.

    • Patient's surname, one forename, other initials.

    • Address, title.

    • Date of birth.

    • The age of children under 12 years and of adults over 60 years must be printed in the box available; the age of children under 5 years should be printed in years and months.

  • Doctor's name must be printed at the bottom of the prescription form, surgery address, telephone number, reference number and primary care organisation. Prescriptions issued by GP registrars, assistants, locums, or deputising doctors should bear the name of a responsible principal.

  • The prescription must be printed in English without abbreviation, the dose must be in numbers, the frequency in words, and the quantity in numbers in brackets (eg, 40 mg four times daily).

  • All points about dose, frequency, strength, preparation, units above must be followed.

  • Supplementary warnings or advice should be written in full.

  • Handwritten alterations should only be made in exceptional circumstances and any alterations must be countersigned in the doctor's own handwriting.

  • Clearly mark duplicates as such.

  • Unused space must be cancelled, or the end of the prescription indicated.

Repeat prescriptions1

It is not unusual for other members of staff to write or for computers to generate repeat prescriptions for you to sign. This can be an efficient time-saving measure but you must ensure that:

  • You have the correct prescription for the correct patient.

  • The patient is being regularly reviewed both in terms of side-effects and with regard to the ongoing need for this medication.

  • The correct dose is issued if there are changing doses over time.

  • Staff are adequately trained in this role.

NB: You are ultimately responsible for these prescriptions.

Repeat dispensing is a type of repeat prescribing which allows community pharmacists to dispense regular medications to suitable patients without the direct involvement of the GP surgery on each occasion the prescription is needed. This is done according to an agreed protocol for patients with stable conditions for periods of time up to one year. The patient is given a batch of prescriptions to take to the pharmacy to be dispensed at regular intervals over the agreed period of time.

Electronic prescriptions2

The electronic prescription service (EPS) is used by more than 95% of surgeries in the NHS. It is a workflow system where prescribers can send prescriptions electronically to a chemist of the patient's choice. This potentially improves safety, and also efficiency and convenience. Prescribing organisations must be authorised to use the service by NHS England.

Shared care prescriptions1

There can potentially be some confusion around ongoing prescriptions of a drug for a condition that is being managed by a hospital team. Ultimately, the responsibility is shared and you have a duty to keep yourself informed about the nature of the drugs that have been prescribed and about their side-effects. You should also be aware of the clinical monitoring arrangements and plan, and the up-to-date relevant clinical guidelines.

In practice, this may be difficult when you may only hear about the hospital visit days or weeks after the event. If you are unsure about the management plan or any of the specific treatment modalities, clarify this with the hospital team.

The General Medical Council (GMC) states that:

  • Decisions about who should take responsibility for continuing care or treatment after initial diagnosis or assessment should be based on the patient's best interests, rather than on your convenience or the cost of the medicine and associated monitoring or follow-up.

  • Shared care requires the agreement of all parties, including the patient. Effective communication and continuing liaison between all parties to a shared care agreement are essential.

Remote prescribing1

Occasionally, you may find yourself needing to issue a prescription without face-to-face contact with the patient. If you have responsibility of care for the patient (or are deputising for a doctor who has), you have prior knowledge about the patient's medical background (or have authorised access to their notes) then you may consider remote prescribing (telephone, fax, email, video link or via a website). In these cases, you must:

  • Establish what all the current medical conditions are, current drug history and any over-the-counter drugs.

  • Carry out an adequate assessment and identify the likely cause of the condition.

  • Ensure that there is enough justification to prescribe and rule out any contra-indications.

If you are not the patient's usual doctor or deputising for the patient's doctor and if you do not have authorised access to their notes, you can still prescribe remotely if you:

  • Fully explain the process to the patient, and give them your name and GMC number.

  • Go through the steps above to ensure safe prescribing.

  • Ensure appropriate follow-up ± monitoring of drug effects and side-effects.

  • Inform the patient's GP. If the patient objects to this, you have the responsibility for providing all necessary aftercare for the patient until another doctor agrees to take over.

Patients abroad

The issues are similar to those where remote prescribing takes place in the UK. However, don't forget:1

  • Products may have a different licensed name, indications and recommended dosage regimen.

  • You may need to be registered with a local regulatory body in the country in which the prescribed medicines are to be dispensed.

  • You should ensure that you have adequate indemnity cover for prescribing for somebody abroad.

Prescribing controlled drugs

The separate Controlled Drugs article has more details.

Prescribing unlicensed medicines or off-label1

Even though a medicine is unlicensed and is lacking a body of evidence to support its use, it may be appropriate to prescribe it to meet a patient's needs. The regulations governing the production of unlicensed medicines have, however, been tightened. Ensure that you:

  • Are satisfied that an alternative, licensed medicine would not meet the patient's needs.

  • Are satisfied that there is a sufficient evidence base and/or you have experience of using the medicine to demonstrate its safety and efficacy.

  • Take responsibility for prescribing the unlicensed medicine and for overseeing the patient's care, including monitoring and any follow-up treatment.

  • Record in the patient's notes the medicine prescribed and, where you are not following common practice, the reasons for choosing this medicine.

NB: GPs should be aware that, if they prescribe unlicensed medicines, they take full clinical responsibility for any adverse events that occur.

Patient group direction (PGD)3

A PGD is a written instruction for the supply and/or administration of a named licensed medicine for a defined clinical condition. This allows, for example, a nurse to supply/administer a prescription-only medicine (POM) to patients without having to refer back to the doctor for each individual patient. This is limited to drugs used in a homogeneous group of patients (eg, standard or travel immunisations, emergency hormonal contraception or analgesia before a minor procedure) where the presenting problems or the needs are likely to be highly consistent.

The development of PGDs is the responsibility of a senior doctor, senior pharmacist and senior nurse in a given area. A PGD is then drawn up at local level with a system of checks and balances to ensure its safety. The health professional working within the PGD is responsible for ensuring the patient fits the criteria drawn up in the PGD. Other health professionals who can supply/administer medicines under a PGD as named individuals include midwives, health visitors, pharmacists, podiatrists, radiographers, ambulance paramedics, dieticians and physiotherapists.

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Particular patient groups

Pregnant women4

Drugs are rarely implicated in congenital malformations. However, this should not be a cause for complacency. Bear in mind effects of drugs on any woman of childbearing age or any man trying to father a child. Use older drugs first-line as these will have a more detailed safety history; use the lowest effective dose.

  • Drugs should be avoided if at all possible in the first trimester of pregnancy, unless the benefit to the mother outweighs the risk to the fetus. The period of greatest risk for teratogenesis is the third to the eleventh week of pregnancy.

  • Drugs given during the second and third trimesters may affect the growth of the fetus or functional development or have a toxic effect on fetal tissue.

  • Drugs given shortly before term can have an adverse effect on labour or on the baby after delivery.

The British National Formulary (BNF) includes information about safety in pregnancy and breastfeeding in the section on each drug, but no drug is safe beyond all doubt in early pregnancy. The BNF stresses that absence of information does not imply safety. Further information is available from the National Teratology Information Service.

Hepatic impairment

Severe liver disease, especially where there is jaundice, ascites or encephalopathy, may alter the response to drugs in several ways. These include:

  • Altered metabolism. Many drugs are eliminated by the liver, and so abnormal function may have an effect on concentrations and therefore efficacy and toxicity.

  • Hypoproteinaemia. If liver disease causes hypoalbuminaemia, drugs which are usually highly protein bound, such as prednisolone and phenytoin, may be present in toxic amounts.

  • Reduced clotting. If clotting factors are not being made as normal by the liver, the sensitivity to oral anticoagulants may be increased.

  • Fluid overload. Drugs which cause fluid retention, such as non-steroidal anti-inflammatory drugs (NSAIDs) and steroids, may cause worsening of ascites or oedema.

  • Hepatotoxicity. Some drugs cause a worsening of liver function and need avoiding, or careful monitoring, in those with pre-existing liver disease.

Renal impairment5

Drug levels may become toxic if not excreted as normal by the kidneys. Efficacy may be compromised in others when renal function is impaired. Many drugs need avoiding or using at lower doses in people with renal disease. Consult the BNF or liaise with the specialist renal clinic team as appropriate for these patients.


There is a separate BNF for children.6 See also the separate Prescribing for Children article for more details.


See the separate Prescribing for the Older Patient article for more details.

Palliative care

See the separate Prescribing in Palliative Care article for more details.

Difficulties with prescriptions

Side-effects and the Yellow Card Scheme

It is worth ensuring that the patient is aware of differences between adverse effects of drug and effects of disease, and any delays in beneficial effects. However, if you suspect that a given symptom is a side-effect, you may consider reporting this if:

  • It is severe - eg, anaphylaxis, blood disorders, severe CNS effects or skin reactions, endocrine dysfunction, etc.

  • It is unexpected - see the BNF for more common or known severe reactions.

  • This is a newly licensed drug (marked by an inverted black triangle); it is then worth reporting all side-effects, major or minor.

  • A baby is born with congenital abnormalities. Consider whether this might be as a consequence of an adverse reaction to a drug. In this case, try to elicit a detailed account of all drugs (including self-medication) that a mother may have taken during her pregnancy.

Doctors, dentists, nurses and pharmacists are encouraged to report any such reactions directly to the Medicines and Healthcare products Regulatory Agency (MHRA) via the Yellow Card Scheme, which can be completed online or by post.7

Drug interactions

Interactions may be:

  • Pharmacodynamic - two or more drugs have similar or antagonistic properties.

  • Pharmacokinetic - one drug alters the absorption, distribution, metabolism or excretion of another. The effect may be potentiating or antagonistic.

Many interactions are harmless but, if you have reason to be concerned, report any suspected drug interaction as you would an adverse effect, using the Yellow Card Scheme (see 'Side-effects and the Yellow Card Scheme', above).

Concordance8 9

Many people with prescriptions for long-term conditions do not take their medicines as intended. In recent years there has been a move away from compliance, which suggests an element of compulsion, to concordance, in which prescriber and patient enter into a partnership concerning the use of medication. The cornerstones of concordance include:

  • The level of information given to patients.

  • Side-effects.

  • The costs of medication.

  • The effect on lifestyle.

NICE refers to the term 'non-adherence' and identifies two types:

  • Intentional: the patient decides not to follow the treatment recommendations

  • Unintentional: the patient wants to follow the treatment recommendations but has practical problems.

They advocate a non-judgemental discussion in which the patient's perceptions and preferences are explored. These two types can overlap.

Some measures can be taken to address concordance problems:

  • It is good practice to have a system to check for prescriptions not collected or dispensed.

  • Issues associated with poor adherence include lack of information about the purpose of a drug, how effective it is, the risk and severity of side-effects, and how to take it. Establish the most effective method of communication with each patient, and give them appropriate information so that they can make informed decisions about taking their medication. This may include, for example, patient information leaflets on conditions or treatments, or the use of pictures, interpreters, and leaflets in different languages or with large print. Give precise written instructions, especially for regimes which vary - for example, some courses of prednisolone.

  • Encourage people to ask questions about their condition and medication, and involve them in decisions. Discussing options will encourage the patient to seek alternatives rather than abandon the treatment altogether.

  • Other issues include complicated methods of administration, unpleasant taste and physical problems such as swallowing difficulties or difficulties in opening the container.

  • Consider the use of pre-filled dispensing boxes for those on multiple medications, or for those who are forgetful.

  • Simplify drug regimes as much as possible (eg, od rather than bd).

  • Weigh up the benefits of combination preparations versus the problems of titrating individual drugs.

See also the separate Prescribing Issues and Concordance article.

Medicines shortages

There have been difficulties obtaining many medicines in recent years - both in the UK and internationally. In 2023, there were recorded shortages in the UK of 111 products. Several reasons have been cited including not only regulatory, production and distribution issues, but also increased patient demand. A full list of medicines that are in short supply can be found on several sites for UK clinicians.10

The NHS has guidance on managing the situation.11

Continue reading below

Other issues

Prescribing for self, family and friends1

The GMC recommends that, as a general rule, you should avoid treating yourself, your family or persons with whom you have a close relationship. In their Good Practice guidelines, they specifically state that: 'Controlled drugs can present particular problems, occasionally resulting in a loss of objectivity leading to drug misuse and misconduct.' They go on to state that you should only consider prescribing a controlled drug if:

  • There is no other person with a legal right to prescribe; and

  • Treatment is immediately necessary to save life, avoid serious health deterioration or alleviate uncontrollable pain.

You must record your actions and be able to justify them as well as record the circumstances that led to the situation. You must also inform that person's own GP unless they object.

Keeping up to date

It is incumbent on anybody prescribing medicines to keep up to date with the ongoing developments and ensure that your prescription is appropriate.1 There are many sources of information to support which include:

  • The BNF and the BNF for Children.

  • The MHRA.12

  • The electronic Medicines Compendium (eMC).13

  • Monthly Index of Medical Specialities (MIMS) prescribing guides.14

  • NICE.15

  • Specific NICE/SIGN guidelines in specific conditions.

If you are uncertain, stay safe and consult a colleague, or look it up.

Further reading and references

  1. Good practice in prescribing and managing medicines and devices; General Medical Council, February 2013 - updated 15 March 2022
  2. Electronic Prescription Service (EPS); Health and Social Care Information Centre (HSCIC) - NHS Digital
  3. Patient Group Directions and Patient Specific Directions in general practice; BMA (2015)
  4. UK Teratology Information Service; UK Health Security Agency (UKHSA).
  5. British National Formulary (BNF); NICE Evidence Services (UK access only)
  6. British National Formulary for Children; NICE Evidence Services (UK access only)
  7. Online reporting site for the Yellow Card Scheme; Medicines and Healthcare products Regulatory Agency (MHRA)
  8. Cushing A, Metcalfe R; Optimizing medicines management: From compliance to concordance. Ther Clin Risk Manag. 2007 Dec;3(6):1047-58.
  9. Medicines adherence: involving patients in decisions about prescribed medicines and supporting adherence; NICE Clinical Guideline (January 2009)
  10. UK drug shortages list; Clinton Direct UK (UK health professionals only)
  11. A Guide to Managing Medicines Supply and Shortages; NHS, Department of Health and Social Care
  12. Medicines and Healthcare products Regulatory Agency (MHRA)
  13. Electronic Medicines Compendium (eMc)
  14. Monthly Index of Medical Specialities (MIMS) prescribing guides
  15. Medicines guidance and prescribing support from NICE

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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