Prescribing the correct medicine is only part of safe treatment. The dosage, frequency, method of administration and interaction with other drugs must also be considered.
A patient can be seriously injured even though the name of the medicine on the prescription is correct. The strength may be excessive, the instructions may be wrong or the patient’s kidney or liver function may mean that a standard dose is unsafe.
An incorrect dosage can also leave a patient undertreated. If too little medicine is given, an infection, heart condition, blood clot or other illness may worsen.
Where an avoidable dosage, interaction or monitoring error causes injury, the patient may be entitled to pursue a wrong dosage medication claim.
What is a medication dosage error?
A dosage error occurs when the patient receives or takes an amount of medicine different from the amount that should reasonably have been prescribed or administered.
Examples include:
- prescribing too high a dose;
- prescribing too little medication;
- supplying the wrong tablet strength;
- giving medication too frequently;
- omitting a required dose;
- administering an additional dose;
- confusing milligrams and micrograms;
- misplacing a decimal point;
- using the wrong liquid concentration;
- administering an intravenous drug at the wrong rate;
- prescribing an adult dose to a child;
- failing to calculate a dose according to weight; or
- failing to reduce a dose following deterioration in kidney or liver function.
Our main guide explains how wrong dosage and other medication error claims are investigated.
Why can a small dosage mistake be dangerous?
Different medicines have different safety margins. With some treatments, there is a considerable range between an effective dose and a toxic one. Others require much more precise control.
A tenfold error can occur when:
- 1.0 is read as 10;
- 0.5 is recorded as 5;
- milligrams are confused with micrograms;
- the number of tablets is mistaken for the total dose; or
- a concentrated liquid is substituted for a weaker preparation.
An NCBI clinical review of medication errors identifies incorrect strength, dosage, timing, preparation and administration as recognised categories of error. It also highlights the risk of unclear abbreviations and decimal points.
The review is American, so it should not be used to define the legal duties of British clinicians. It is nevertheless a useful clinical source explaining how these mistakes occur and why checking systems are important.
Who can make a dosage error?
An incorrect dose can originate at several points.
The prescribing clinician
A GP, hospital doctor, nurse prescriber, pharmacist prescriber or private clinician may select the wrong dose or fail to consider the patient’s individual circumstances.
The pharmacy
A pharmacy may supply the wrong strength, attach incorrect instructions or dispense a different formulation from the one prescribed.
Hospital or nursing staff
Staff may give the wrong number of tablets, use the wrong infusion rate, administer medication twice or give it to the wrong patient.
Care-home staff
A care home may misread the medication administration record, omit a dose, repeat treatment or continue medication that has been stopped by a clinician.
The patient
Patients can make mistakes where instructions are unclear or contradictory. A patient following the label and professional advice should not automatically be blamed for an error originating from poor prescribing, dispensing or communication.
What is a dangerous drug interaction?
A drug interaction occurs when one medicine changes the way another works. It may increase toxicity, reduce effectiveness or produce a harmful combined effect.
Some interactions are known and deliberately managed because the benefits justify the risk. Negligence may arise where a significant interaction should have been recognised but was overlooked or inadequately monitored.
A dangerous interaction might involve:
- two medicines increasing the risk of bleeding;
- several drugs causing excessive sedation;
- combined treatment lowering blood pressure;
- medicines collectively affecting heart rhythm;
- one drug increasing the concentration of another;
- duplicated medicines from the same drug group;
- prescribed medicine interacting with an over-the-counter product; or
- a medicine worsening an existing disease.
The existence of an interaction does not automatically establish negligence. The legal question is whether the combination was clinically reasonable and whether the patient received appropriate information, monitoring and follow-up.
Who should check for interactions?
The primary prescribing decision rests with the clinician authorising the treatment. That clinician should have sufficient information about the patient’s health, existing medication, allergies and relevant test results.
The dispensing pharmacist also provides an important safety check. The General Pharmaceutical Council’s professional standards require pharmacists to use professional judgement, obtain the information needed to provide appropriate care and work effectively with other healthcare professionals.
Responsibility may be shared where:
- the prescriber selected an unsafe combination;
- a computer warning was overridden without proper consideration;
- the pharmacist failed to query an evident interaction;
- hospital medication changes were not communicated to the GP;
- the patient’s complete medication history was unavailable; or
- different clinicians prescribed without effective coordination.
Kidney and liver function
The kidneys and liver help remove or break down many medicines. If either is functioning poorly, medication may accumulate and reach toxic levels.
A dosage may need to be reduced according to:
- kidney function;
- liver function;
- age;
- weight;
- hydration;
- frailty;
- other illnesses; and
- medicines taken at the same time.
A wrong dosage claim may arise where a clinician:
- failed to check kidney or liver function;
- prescribed before reviewing available results;
- continued treatment despite deterioration;
- failed to adjust the dose;
- failed to arrange repeat blood tests; or
- failed to act after toxic symptoms emerged.
The issue is not simply whether the patient had abnormal results. Independent evidence must show what a reasonably competent clinician should have done and whether different treatment would probably have prevented the injury.
What is medication-monitoring negligence?
Certain medicines require continuing checks to ensure treatment remains within a safe range.
Monitoring might include:
- blood tests;
- blood-pressure checks;
- heart monitoring;
- kidney or liver function tests;
- blood-clotting measurements;
- checks of drug concentration;
- weight measurements; or
- assessment for recognised side effects.
Medication-monitoring negligence may occur where:
- required tests are not arranged;
- the patient is not told that monitoring is necessary;
- abnormal results are overlooked;
- results are filed without clinical review;
- nobody takes responsibility under a shared-care arrangement;
- treatment continues after the patient misses essential tests; or
- reported symptoms do not prompt urgent reassessment.
The GMC prescribing guidance makes clear that prescribing involves more than signing a prescription. The clinician must have adequate information and manage treatment safely.
Wrong formulation and release rate
Some medicines are manufactured in immediate-release and modified or extended-release forms. They may contain the same active ingredient but release it into the body at different rates.
Substituting one form for another can alter the amount of medicine entering the bloodstream over a particular period.
A claim may arise where:
- the prescriber selected the wrong formulation;
- the pharmacy dispensed a different formulation;
- the label failed to identify the correct version;
- the patient was given incorrect instructions; or
- staff crushed or altered a tablet that should have remained intact.
The original prescription, packaging and dispensing record will be particularly important in these cases.
Medication errors following hospital discharge
A patient’s dosage may change during a hospital admission. Problems arise if the new instructions are not communicated accurately to the GP, pharmacy, care home or patient.
Examples include:
- the patient taking both the old and new doses;
- a GP continuing the previous repeat prescription;
- a discontinued medicine being supplied again;
- two brands of the same drug being taken together;
- a care home receiving inconsistent records; or
- the patient being discharged without clear instructions.
The NICE medicines optimisation guideline addresses medication reconciliation and communication between healthcare settings.
Where an injury occurs after discharge, it is necessary to compare the hospital prescription, discharge summary, GP record, pharmacy history and information given to the patient.
What injuries can an incorrect dose cause?
Potential consequences include:
- overdose or toxicity;
- kidney or liver failure;
- internal bleeding;
- stroke;
- blood clots;
- respiratory depression;
- loss of consciousness;
- seizures;
- heart-rhythm disturbance;
- severe low blood pressure;
- falls and fractures;
- deterioration of the untreated condition;
- permanent disability; or
- death.
A low dose can be as important as an excessive one. If the patient does not receive enough treatment, the underlying disease may progress.
What must be proved in a wrong dosage claim?
A successful claim normally requires proof that:
- The dosage, formulation, frequency or monitoring was inappropriate.
- The relevant doctor, pharmacist or care provider failed to exercise reasonable care.
- The error probably caused or materially worsened the injury.
- The patient suffered compensatable harm or financial loss.
Expert evidence will usually be required from a professional working in the relevant clinical field. Pharmacy evidence may address dispensing and interaction checking. Medical evidence will consider the physical consequences and what would probably have happened with the correct dose.
What if the patient took the medicine exactly as instructed?
Following professional instructions will usually be important evidence supporting the patient’s account.
The defendant may argue that the patient misunderstood the label, took additional doses or combined the medicine with an undisclosed product. The instructions, consultation records, dispensing label and witness evidence must therefore be examined.
If the directions were unclear, conflicting or objectively unsafe, the fact that the patient followed them does not necessarily prevent a claim.
What evidence should be retained?
Preserve:
- all remaining medicine;
- boxes, bottles and blister packs;
- dispensing labels;
- dosage instructions;
- patient information leaflets;
- photographs of the medicine and packaging;
- the repeat-prescription list;
- hospital discharge documents;
- blood-test results available to the patient;
- messages with the GP or pharmacy;
- details of when each dose was taken;
- a chronology of symptoms; and
- receipts for treatment, travel and care.
Where possible, record the medicine’s name, strength, batch number and expiry date. Do not dispose of the only remaining evidence.
What compensation may be available?
Depending upon the injury, compensation may include:
- pain and suffering;
- hospital treatment;
- rehabilitation;
- care and assistance;
- loss of earnings;
- medical expenses;
- travel costs;
- equipment and home adaptations;
- psychological injury; and
- future financial losses.
Where a dosage or interaction error causes death, the estate and qualifying dependants may be entitled to pursue a fatal medication negligence claim.
How long do I have to bring a claim?
The usual period is three years from the negligent treatment or from the date the patient first had sufficient knowledge that their injury might be connected with negligence, if later.
Different rules apply to children and may apply to people lacking the mental capacity required to conduct proceedings.
Neither a complaint nor a regulatory investigation stops time running. Legal advice should be obtained as soon as possible.
Specialist pharmacy knowledge
Claims involving incorrect dosages and drug interactions can require detailed analysis of technical prescribing and dispensing information.
Our team includes specialist pharmacy knowledge to help identify:
- dosage discrepancies;
- potential interactions;
- medicines requiring monitoring;
- inconsistencies between records;
- dispensing and labelling problems; and
- the appropriate independent experts.
This allows the legal investigation to concentrate on the medication issues that are most likely to determine liability and causation.
Speak to our medication error solicitors
If you have been injured by an incorrect dosage, dangerous drug interaction or failure to monitor your medication, you may be entitled to compensation.
Our specialist medication error claims team can investigate the prescribing, dispensing and monitoring of your treatment and advise whether the evidence supports a claim.
For free initial advice, contact Hutcheon Law or telephone 0151 724 7121.
Contact Us Now To Claim
For Further Readings:
Repeat Prescription Negligence: When Should Long-Term Medication Be Reviewed?
Dangerous Medication Combinations and Prescription Errors
Medication Error Claims: Can You Sue a Doctor or Pharmacist?
