Medication Error Claims: Can You Sue a Doctor or Pharmacist?

Medicines should improve a patient’s health or help control the symptoms of an existing condition. Unfortunately, serious harm can occur when the wrong medicine is prescribed, an excessive dosage is given, dangerous drug combinations are overlooked or repeat prescriptions continue without a proper review.

Medication errors can lead to allergic reactions, internal bleeding, organ damage, breathing difficulties, loss of consciousness and other serious complications. For older or frail patients, the first warning may be less obvious: confusion, dizziness, low blood pressure or an unexplained fall.

A patient injured by a preventable medication mistake may be entitled to bring a medication error claim against a doctor, pharmacist, hospital, care provider or another healthcare professional. However, the existence of a side effect does not, by itself, prove negligence. It is necessary to establish an avoidable failure and show that it caused additional injury.

The growing scale of medication use in England

A major University of Liverpool-led study published in Nature Health examined 5.8 billion medicines dispensed to 52.6 million people in England between November 2019 and December 2024.

The researchers found that the number of medicines dispensed increased considerably with age. By age 50, approximately 15% of people had received five or more concurrent medicines. By age 70, that figure had risen to 42%.

Receiving several medicines is not automatically unsafe. A patient with multiple health conditions may genuinely require each treatment. The concern arises when medicines accumulate without anyone standing back and considering whether every drug remains necessary, whether the dosages are still appropriate and whether the combined treatment is causing harm.

Separate peer-reviewed research into adverse drug reactions and hospital admissions, conducted by researchers from the University of Liverpool and Bangor University, reviewed 1,187 medical admissions lasting more than 24 hours.

The researchers found that adverse drug reactions caused or contributed to 16.5% of the admissions studied. Patients affected by an adverse reaction were taking an average of 10.5 medicines, compared with 7.8 among other patients. Just over 40% of the reactions were classified as avoidable or possibly avoidable.

The study estimated that hospital admissions associated with adverse drug reactions could cost NHS England approximately £2.21 billion annually. That was a national projection based on the hospital studied, rather than a calculation of every affected patient in England, but it illustrates the scale of the problem.

What is overprescribing?

Overprescribing happens when a patient is given medication they do not clinically need, when a safer or more suitable treatment should have been considered, or when the risks of continuing the medicine outweigh its likely benefits.

A medicine may have been reasonable when it was first prescribed but become unsuitable as the patient grows older or their health changes. Problems can also arise when medication is continued for years without a proper review, when a patient’s kidney or liver function makes the usual dosage unsafe, or when several medicines interact and cause harmful side-effects.

Common examples of overprescribing include:

prescribing medication when lifestyle changes, therapy or another form of treatment may have been more appropriate;
prescribing a drug that is generally used for the condition but is unsafe for that particular patient;
continuing medication after the patient’s condition, age or health needs have changed;
repeatedly prescribing a medicine without reviewing whether it is still needed;
failing to reduce or stop strong painkillers intended for short-term use; and
adding further medication to treat side-effects without recognising that an existing drug may be causing the problem.

The Government’s national overprescribing review identified inappropriate prescribing, ineffective prescription reviews, repeat prescribing and failures during transfers of care as important areas requiring improvement.

Not every instance of overprescribing amounts to medical negligence. Many patients properly require several medicines to manage complex health conditions. A legal claim may arise, however, where a doctor, pharmacist or healthcare provider failed to act with reasonable care and an avoidable prescribing, monitoring or medication-review error caused injury.

Our medication error claims solicitors can obtain and examine the relevant medical and pharmacy records, identify how the medication was prescribed and reviewed, and investigate whether warning signs were missed. With specialist pharmacist knowledge available within our team, we can assess possible overprescribing and drug-interaction issues at an early stage before arranging the independent expert evidence required to support a claim.

What is polypharmacy?

Polypharmacy generally means taking several medicines at the same time. Five or more medicines is a commonly used measure, although the number alone does not determine whether the treatment is appropriate.

NHS England describes problematic polypharmacy as including circumstances where:

a medicine is no longer clinically necessary;
the possible harm outweighs the expected benefit;
a combination of medicines is causing or could cause harm;
the patient does not understand the treatment; or
the overall medication regime has become difficult or unsafe to manage.

The Government’s national overprescribing review identified unnecessary repeat prescribing, poor communication and fragmented care as areas requiring improvement. It also highlighted the importance of offering alternatives where medication is not the most appropriate treatment.

Overprescribing can occur when a medicine was properly prescribed initially but is allowed to continue long after its original purpose has disappeared. The failure is not necessarily the decision made years earlier. It may be the subsequent failure to review that decision as the patient’s age, health and other medication changed.

Why can medication become more dangerous with age?

Older patients do not always process medicines in the same way as younger adults. Changes in kidney or liver function can mean that a drug remains in the body for longer. Weight loss, dehydration, frailty, dementia and additional health conditions can also alter the balance between the benefits and risks of treatment.

A dosage that was once suitable may gradually become excessive. A new medicine may also interact with a drug that the patient has taken safely for many years.

Medication-related harm can cause:

dizziness or fainting;
low blood pressure;
falls and fractures;
confusion or apparent dementia-like symptoms;
difficulty walking;
severe drowsiness;
irregular heartbeats;
internal bleeding;
breathing difficulties;
kidney or liver damage;
seizures;
allergic reactions;
loss of consciousness; or
death.

The emergence of one of these symptoms does not necessarily prove that a medicine is responsible. It should nevertheless prompt a proper clinical assessment, particularly when the patient is frail, has recently started a new drug or is taking several different medicines.

Patients should not suddenly stop prescribed medication without medical advice. Abrupt withdrawal from some medicines can itself cause serious harm.

What is a prescribing cascade?

A prescribing cascade can develop when the side effect of one medicine is mistaken for a new medical condition.

Instead of recognising that the original drug is causing the problem, another medicine is prescribed to treat the side effect. That second drug may then cause further difficulties, resulting in an increasingly complicated treatment regime.

For example, a patient might develop dizziness or swelling after starting medication. If the connection with the original drug is missed, another medicine may be added instead of reviewing whether the first treatment remains suitable.

A prescribing cascade is not automatically negligent. It could support a claim where a reasonably competent clinician should have recognised the side effect, reviewed the existing treatment and avoided the resulting injury.

Where do medication errors happen?

An NCBI clinical review of medication dispensing errors explains that mistakes can occur at almost any stage of treatment, including:

ordering and prescribing;
recording the prescription;
transferring information between systems;
preparing and dispensing the medicine;
administering it to the patient; and
monitoring the patient after treatment begins.

Although this is an American clinical review, the stages it identifies are equally useful when investigating how a medication error occurred in England and Wales. British professional standards and independent expert evidence must then be used to decide whether the care was negligent.

The review identifies recurring problems such as inaccurate records, poor communication, failure to obtain an allergy history, inadequate checking and failures between primary and secondary care.

This means that a claim should not automatically concentrate on the last professional who handled the medicine. The complete path from prescribing to administration must be investigated.

When can overprescribing amount to medical negligence?

Overprescribing may amount to medical negligence when a reasonably competent clinician should have recognised that a medicine was unnecessary, unsuitable or unsafe but failed to act.

Potential examples include:

prescribing medication without an adequate clinical reason;
continuing a medicine after it was no longer required;
repeatedly issuing medication without a suitable review;
failing to reconsider treatment after repeated falls or collapses;
prescribing medicines known to create a dangerous interaction;
failing to consider age, frailty, weight or other medical conditions;
failing to alter a dosage after kidney or liver function deteriorated;
overlooking a recorded allergy;
failing to arrange necessary blood tests;
failing to act upon abnormal monitoring results;
duplicating medication prescribed by another clinician; or
failing to investigate reported side effects.

The General Medical Council’s prescribing guidance requires doctors to prescribe safely and to have sufficient information about the patient and their treatment.

Its specific standards for repeat prescribing state that a doctor must ensure every repeat prescription remains safe and appropriate. The correct dosage should be prescribed, the patient’s condition should be monitored and patients requiring further examination should receive an appropriate clinical review.

A repeat-prescription system should make treatment more convenient. It should not allow potentially harmful medication to continue indefinitely without anyone reconsidering it.

Who should receive a medication review?

The purpose of a medication review is not simply to count the patient’s tablets. It should consider:

why each medicine was started;
whether it continues to provide a benefit;
whether the dosage remains appropriate;
whether monitoring is required;
whether one drug is affecting another;
whether the patient is experiencing side effects;
whether the patient can manage the treatment safely; and
whether any medicine could safely be reduced or stopped.

The NHS England structured medication review programme identifies several groups who may particularly benefit from a review. These include people taking ten or more medicines, those living with severe frailty, care-home residents, patients experiencing falls or recent hospital admissions and people taking medicines commonly associated with errors.

Whether the failure to provide a review amounts to negligence will depend on the individual circumstances. A missed review must also have made a difference to the outcome. If the same treatment would reasonably have continued following a competent review, the absence of that review may not have caused the injury.

Can a pharmacist be sued for giving someone the wrong medicine?

A pharmacist or pharmacy business may be liable where a dispensing or professional error causes injury.

A pharmacy negligence claim could involve:

dispensing the wrong medicine;
supplying medication intended for another patient;
dispensing the wrong dosage or strength;
placing incorrect directions on the label;
supplying an incorrect quantity;
providing the wrong form of a medicine;
failing to identify an obvious discrepancy;
overlooking an allergy or interaction apparent from the available information;
failing to contact the prescriber about a serious concern; or
giving incorrect advice about how the medicine should be taken.

The General Pharmaceutical Council’s Standards for Pharmacy Professionals require pharmacists and pharmacy technicians to provide person-centred care, communicate effectively, use their professional judgement and make the patient’s safety their first concern.

A pharmacist is not automatically responsible whenever medication selected by a doctor causes an adverse reaction. The clinical decision to initiate treatment may rest principally with the prescriber. The pharmacist’s responsibility will depend on what information was available and whether a reasonably competent pharmacist should have identified or acted upon the problem.

A claim will commonly be directed against the pharmacy business, owner or employer rather than solely against the individual employee.

Medication errors in hospitals and care homes

Medication errors can also occur when a nurse, care worker or other professional administers treatment.

Examples include:

giving medicine to the wrong patient;
administering an excessive dosage;
giving a second dose after the first was not recorded;
omitting essential medication;
using the wrong method of administration;
administering an intravenous drug at an unsafe rate;
failing to follow the prescription;
failing to record the treatment accurately; or
failing to obtain urgent help after the patient deteriorated.

The hospital trust or care provider may be legally responsible for mistakes committed by its employees. It may also be responsible for unsafe systems, inadequate staffing, poor training or failures in communication.

Medication reconciliation following hospital treatment

Medication reconciliation means producing an accurate list of everything a patient is taking. It should include prescribed medicines, drugs supplied by different specialists and relevant over-the-counter products.

Admission to and discharge from hospital are vulnerable points. A hospital might stop, start or alter medication, but the change may not be communicated clearly to the GP, pharmacy, care home or patient.

A failure to reconcile medication can result in:

a discontinued drug being restarted;
the same treatment being prescribed twice;
an essential medicine being omitted;
incompatible medicines being combined;
the wrong dosage continuing; or
different healthcare providers giving contradictory instructions.

The NICE medicines optimisation guideline addresses safe use of medicines and communication when patients move between healthcare settings. A failure to communicate an important medication change may support a claim if it resulted in avoidable injury.

Failure to warn about the risks of medication

Medication can be correctly prescribed and dispensed, yet a claim may still arise if the patient was not properly informed about a material risk or reasonable alternative.

The Supreme Court’s decision in Montgomery v Lanarkshire Health Board established the modern legal approach to informed consent. Patients should be told about material risks that a reasonable person in their position would consider significant, together with reasonable alternative treatments.

A claimant would ordinarily need to show that, if properly informed, they would have declined the medicine, chosen an alternative or sought further advice, and that the resulting injury would probably have been avoided.

What must be proved in a medication error claim?

A medication error claim normally requires proof of three essential matters:

a. Breach of duty to you

The treatment, prescribing, dispensing, administration or monitoring fell below the standard reasonably expected from a competent professional. An independent expert will ordinarily assess whether the doctor, pharmacist, nurse or other provider acted negligently.

b. Causation – proof of injury

The mistake probably caused or materially worsened the patient’s injury.

Causation can be difficult where someone already had several illnesses. The defendant may argue that the deterioration was caused by the original condition, age or frailty rather than the medicine.

It is not enough to identify an error if the same injury would probably have occurred without it.

c. Injury and loss

The patient must have suffered an injury or financial loss. A mistake corrected before causing harm will not normally result in compensation.

Who may be legally responsible?

Depending on where the failure occurred, a claim might be made against:

an NHS hospital trust;
a GP or the relevant general practice indemnity scheme;
a private doctor or clinic;
a community pharmacy business;
a care-home operator;
an independent prescribing service; or
more than one healthcare provider.

Many cases involve overlapping responsibilities. A hospital may alter medication, a GP may continue the prescription and a pharmacy may dispense it. Each provider’s records and responsibilities must therefore be considered.

What evidence should be preserved?

Anyone who suspects a medication error should retain, where possible:

the medicine and its original packaging;
dispensing labels;
patient information leaflets;
photographs of the tablets, packaging and labels;
repeat-prescription lists;
hospital discharge information;
medication administration records;
correspondence with the GP, hospital, pharmacy or care home;
a chronology of symptoms, falls and hospital admissions;
receipts for treatment, care, equipment and travel; and
the details of relatives or carers who witnessed the deterioration.

A solicitor can obtain the complete GP, hospital, pharmacy and care records. These may reveal prescription histories, medication reviews, warnings, blood results, allergy information and changes made during transfers between services.

What compensation can be claimed?

Compensation depends upon the seriousness and duration of the injury. It may include:

pain, suffering and loss of amenity;
additional medical treatment;
rehabilitation and therapy;
care provided by relatives;
professional care;
mobility equipment;
home adaptations;
loss of earnings;
travel and medical expenses;
future treatment and support; and
compensation for injuries caused by medication-related falls.

If the medication error caused a death, the deceased’s estate and qualifying dependants may be able to pursue a fatal accident compensation claim.

How long do medication error claims take?

The time required will depend on the medical complexity of the case, the number of potential defendants and whether liability is admitted. The initial investigation normally includes obtaining the records, preparing a detailed chronology and securing independent expert evidence. Where the effects of the injury are continuing, further evidence may be required to assess the patient’s prognosis and future needs. Many claims settle without a trial, but court proceedings may be necessary where liability or the value of compensation remains disputed.

Is there a time limit to make a claim for wrong medication?

The usual time limit for a clinical negligence claim in England and Wales is three years from:

the date of the negligent treatment; or
the date the patient first had sufficient knowledge that their injury might be connected with negligent treatment, if later.

The applicable provisions are contained in the Limitation Act 1980.

Different rules apply to children and may apply where a person lacks the mental capacity required to conduct legal proceedings.

Making a complaint to a hospital, GP or pharmacy does not stop the limitation period. Patients should obtain legal advice promptly even if the healthcare provider is still investigating what happened.

What should I do if I have received the wrong medication?

Your health must come first. Contact the dispensing pharmacy, prescribing clinician, NHS 111 or another appropriate medical professional immediately.

Call 999 in an emergency, including where the person has collapsed, cannot breathe normally, is unconscious or is experiencing swelling of the face, mouth or throat.

Do not discard the medicine or packaging. Do not take further doses of a medicine known to have been supplied to the wrong patient. However, do not discontinue established prescribed treatment merely because you are worried about possible side effects without first obtaining appropriate medical advice.

Speak to our medication error solicitors

If you or a family member has been injured because of the wrong medication, an excessive dosage, overprescribing, inadequate monitoring or a pharmacy dispensing mistake, you may be entitled to compensation.

Our medical negligence solicitors can investigate the entire medication pathway, identify the appropriate defendant and obtain the expert evidence required to assess your claim.

For free initial advice, contact Hutcheon Law or telephone 0151 724 7121.

Frequently asked questions

Is every adverse drug reaction medical negligence?

No. A patient can experience a recognised side effect even when the medicine was prescribed and monitored properly. A claim requires evidence of an avoidable failure and proof that it caused injury.

Can I claim if a repeat prescription was never reviewed?

Possibly. It will be necessary to show that a reasonably competent clinician should have reviewed the treatment and that an appropriate review would probably have prevented the injury.

Can I sue a pharmacist for dispensing the wrong dosage?

A pharmacy may be liable if it negligently supplied the wrong strength, quantity, form or instructions and the mistake caused harm.

What if both the doctor and pharmacist made mistakes?

More than one healthcare provider can be responsible. The prescription, dispensing records and expert evidence will help determine what each provider should have done.

Can I claim if the medication caused me to fall?

Potentially. It must be established that the medication probably caused or materially contributed to the fall and that the prescribing, monitoring or failure to review the treatment was negligent.

This article provides general information about the law in England and Wales. It is not a substitute for individual legal or medical advice. Patients should not stop or alter prescribed medication without appropriate medical guidance.