Medication errors: the role of the patient


Professor Nicky Britten, Institute of Health Services Research, Peninsula Medical School, St Luke's Campus, Exeter, EX1 2LU, UK.
Tel: 01392 264859
Fax: 01392 262926


1. Patients and their carers will usually be the first to notice any observable problems resulting from medication errors. They will probably be unable to distinguish between medication errors, adverse drug reactions, or ‘side effects’.

2. Little is known about how patients understand drug related problems or how they make attributions of adverse effects. Some research suggests that patients' cognitive models of adverse drug reactions bear a close relationship to models of illness perception.

3. Attributions of adverse drug reactions are related to people's previous experiences and to their level of education. The evidence suggests that on the whole patients' reports of adverse drug reactions are accurate. However, patients do not report all the problems they perceive and are more likely to report those that they do perceive as severe. Patients may not report problems attributed to their medications if they are fearful of doctors' reactions. Doctors may respond inappropriately to patients' concerns, for example by ignoring them. Some authors have proposed the use of a symptom checklist to elicit patients' reports of suspected adverse drug reactions.

4. Many patients want information about adverse drug effects, and the challenge for the professional is to judge how much information to provide and the best way of doing so. Professionals' inappropriate emphasis on adherence may be dangerous when a medication error has occurred.

5. Recent NICE guidelines recommend that professionals should ask patients if they have any concerns about their medicines, and this approach is likely to yield information conducive to the identification of medication errors.

A medication error is not the same as an adverse drug reaction, although the two may overlap. Ferner and Aronson have defined a medication error as ‘a failure in the treatment process that leads to, or has the potential to lead to, harm to the patient’[1]. They identified four different scenarios: adverse drug reactions that arise from medication errors; adverse drug reactions that do not arise from errors; medication errors that cause harms that are not adverse drug reactions; and medication errors that do not cause adverse events. From the point of view of most patients, the first three scenarios are indistinguishable, as they all refer to harms associated with the use of medications. In addition, the language used by professionals may differ from that used by patients, for whom the term ‘side-effect’ generally serves as a generic descriptor, even though, technically, a side-effect is only one type of adverse drug reaction [2]. Furthermore, patients may not appreciate that not all adverse events are due to adverse drug reactions. Here I shall use the term ‘adverse effects’ when taking the doctor's perspective and ‘side-effects’ when taking the patient's.

The challenge for the patient

Clearly, the people who experience any harm or suffering resulting from medication errors are the patients and possibly also their relatives and carers. Patients and their spouses or carers will in many cases be the first to notice any observable problem that arises from a medication error. In some cases, adverse events are immediate or well known. However, other events may be delayed or unfamiliar and patients may not realize that the problem has anything to do with the medication they are taking. The challenge for patients includes the perception, interpretation, and attribution of any medication-related problems.

Different people are more or less sensitive to physical symptoms. The correct interpretation and attribution of any symptoms have to compete with a variety of alternative explanations, including symptoms of the underlying disease; normal wear and tear; extraneous factors, such as stressful life events; and problems caused by other medications for those taking multiple medications. We know very little about how people make attributions of medication-related problems. DeWitt and Sorofman investigated the cognitive models used for patients' understandings of side-effects of drugs, by comparing them with the prototype used for understanding illness [3]. They defined a prototype as a cognitive approach that is simple and yields reliable classification of new cases. In their questionnaire-based study of 338 adults attending a family medicine clinic in the USA, 53% of the respondents reported personal experience of a side-effect. In their qualitative and quantitative responses, the elements of the respondents' side-effects prototype were identical to those of their illness perception prototype: cause, symptom, time, consequence, and cure. In their narrative descriptions, nearly half (44%) of those who reported an adverse drug reaction mentioned the cause of the reaction by naming the implicated drug or drug family. When asked directly, 94% provided the name of a drug or drug class. In relation to the other elements, 98% of respondents described symptoms, 10% gave information about the time of onset or duration, 24% described the consequences in terms of stopping taking the drug or other responses, and 3% mentioned a cure. There was virtually no other information in people's narrative descriptions beyond these five elements. People with previous experience of a side-effect believed that side-effects in general were less severe than those without such previous experience. Those with more formal education believed side-effects to be less severe than less educated respondents.

Other studies have shown that some people carry out their own evaluations of prescribed medicines, to see if the medicines are working and to assess their impact on their daily lives [4]. These evaluations include weighing up the perceived costs and benefits of medications and responding to perceived side-effects. They may confirm or disconfirm people's initial attributions of medication-related effects; if the patient considers the attribution to have been confirmed, they may decide to stop taking the medication.

Quality of patients' reports

Professionals may have doubts about the quality of patients' reports of what they perceive to be side-effects. However, in general such doubts are not supported by the available evidence. In a questionnaire study of 837 patients for whom nine recently marketed ‘black triangle’ drugs had been prescribed, Jarernsiripornkul et al. asked respondents to identify any symptoms they thought could have been due to the drugs [5]. They then classified these symptoms according to the probability that each symptom was caused by the index drug, using the literature on adverse drug reactions. Nearly three-quarters (71%) of the symptoms were classified as being probably or possibly related to the drugs studied.

In their review of patient reporting of suspected adverse drug reactions, Blenkinsopp et al. concluded that there was some evidence that patient and professional reports are of similar quality [6].


Patients who, however tentatively, attribute their symptoms to their medicines may be deterred from saying anything, for fear of seeming critical of the prescriber. Jarernsiripornkul et al. found that only 54% of patients who identified potential side-effects had reported some or all of them to their doctor [5]. In the subsample of 344 patients for whom tramadol had been prescribed, the patients who perceived the most bothersome symptoms as being severe were also significantly more likely to have informed their doctors than those who perceived the symptoms as being mild [7]. Of the symptoms that patients who had used tramadol or venlafaxine claimed to have reported, only 23% were documented in their primary-care records [5].

Without the expectation that their fears will at least be listened to and taken seriously, patients may decide to say nothing, even if they have stopped taking the drug as a result. If the patient remains silent, this is likely to lead the prescriber to conclude that there are no problems and that the medicine can safely be prescribed again. If the patient does say something, however tentative, and their attribution is correct or at least plausible, this may make the prescriber feel guilty. Either way, the consultation may not include an unemotional and objective consideration of the facts and what needs to be done.

Some studies have measured the extent to which patients mention side-effects in consultations with doctors, with varying results. Sleath et al. videotaped consultations between 467 patients with chronic conditions and their primary-care physicians; they found that only 9% made a complaint about side-effects [8]. Patients were significantly more likely to make a complaint (not just about side-effects) if they were asked more medication questions by their doctor. White and Sander conducted a postal survey of 604 adults with asthma and the parents of 1230 children with asthma, and found that 66% of the adults and 61% of the children had had side-effects of medications [9]. Of these, 72% of the adults and 82% of the children claimed to have mentioned side-effects to their doctors.

In their systematic review of communication between patients and healthcare professionals about medicines, Cox et al. concluded that patients were more likely to express concerns if their doctor asked them more questions, if they used more medicines, if they perceived their health to be poor, or if their doctor was younger [10]. Doctors responded to patients' complaints about medicines in a variety of ways: by changing the medicine; by providing education; by telling patients that the benefits outweighed the harms; by saying that there were no alternatives or that adverse effects were to be expected. In one study, doctors ignored patients' medication complaints in >25% of cases [8].

Patients require information to help them make correct attributions and differentiate between an error, a side-effect, the drug's normal therapeutic action, and the symptoms of their underlying condition(s), if any. Although it is true that not all patients want information, the literature suggests that patients want more information than they receive about adverse effects, and that doctors tend to underestimate the extent to which patients want this information. In a study of 344 patients with rheumatoid arthritis, significantly more patients wanted information than wanted to be involved in making decisions [11]. In their review of written information about medicines, Raynor et al. also found that most patients wanted to know about side-effects, but that professionals were sometimes reluctant to provide this information [12]. Some professionals felt that the purpose of written information was to improve adherence.

In a study of 271 general practice patients, Makoul et al. compared patients' and doctors' questionnaire responses with videotapes of the consultations [13]. Patients reported that doctors provided the majority of the information they received about prescription medicines. Doctors rated the importance of explaining all the risks of any medication as a mean 6 out of 10, but the video analysis showed that risks were discussed in only 3.1% of consultations analysed.

Although professionals may find it difficult, and may judge that some patients do not have the ability to comprehend information about the risk of adverse effects, the problem should not be ignored. The challenge for professionals, as in the communication of all information about risks, is to judge how much information an individual patient actually wants and is able to comprehend. One way of opening this up is to ask the patient what they already know and how much they want to know. In general, risk communication should be a two-way process, in which professionals and patients exchange information and opinions about those risks [14]. Professionals need to support patients by providing the relevant data in accessible, often visual, formats. Raynor et al. concluded that numerical risk information, rather than verbal descriptors, ensured a more accurate estimation of the probability and likelihood of adverse effects [12].

Risks of inadequate information

The dangers posed by inadequately informing patients are well known. In a study of patients admitted to hospital with an acute gastrointestinal bleed who had been taking nonsteroidal anti-inflammatory drugs and matched controls from local general practices, Wynne and Long found that the hospital patients knew less about the adverse effects of their drugs but had also been more compliant [15]. More generally, if a medication error has occurred, the patient may be placed at risk if the professional focuses exclusively on adherence. If the patient has stopped taking a medicine, it is particularly important to find out why, rather than simply emphasizing the importance of adherence. In this case, it is more important for the professional to ask patients about any symptoms they may have experienced. Jarernsiripornkul et al. suggested that a symptom checklist, such as that used in their study, could help identify problems that patients perceive as being related to their drug therapy [5].

Preventing medication errors

The role of the patient in preventing medication errors has not been well studied. It has been suggested that allowing patients in hospital to administer at least some of their own medicines might help [16], and a system to empower patients has been proposed [17]. However, patients frequently make medication errors and the risk is greater in elderly patients. In a study of 178 elderly, chronically ill, ambulatory patients, 59% made one or more errors in their medications, and the errors were potentially serious in 26%; those who erred at all were more likely to make multiple mistakes than single mistakes, the average number being 2.6 errors per error-making patient [18]. In a more recent study in 6718 elderly subjects being cared for at home, 30% had evidence of a potential medication problem or were taking a drug considered inappropriate for older people; the risk increased linearly with the number of medications taken [19]. Information leaflets may help to reduce patients' own medication errors [20].

Parent involvement in prescribing was not found to be beneficial in a study in 1410 pairs of parents and children, of whom 1097 had a total of 2234 orders or prescriptions written, 1289 (58%) being associated with at least one medication error; of 1755 errors, 232 were serious and preventable [21]. A patient-centred health information technique designed to enhance communication between parents and clinicians during emergency care was used in 654 patients. The parents used the technology to enter data on symptoms and medication-related history and a printout provided recommendations to the clinicians. However, the system did not significantly affect the number of errors.

The patient and pharmacovigilance

The role of the patient extends beyond the resolution of their own difficulties, although they may not always know this. They also have a role to play in pharmacovigilance, either directly or indirectly. The two main methods of identifying new reactions are spontaneous reporting of suspected adverse drug reactions and prescription event monitoring for new drugs. Both methods require patients to report their symptoms, either to healthcare professionals or directly to the responsible regulatory authorities. The low level of reporting by healthcare professionals is well known [22], and patients are increasingly being allowed and encouraged to report suspected adverse drug reactions directly.

In their review of patient reporting systems in six countries, Blenkinsopp et al. concluded that there was some evidence that patients' reports and professional reports were of similar quality; that patients report different adverse drug reactions from professionals; that patients report new adverse drug reactions and report more quickly than professionals; and that patients' reports are initially more time-consuming to process [6]. Overall, they concluded that the limited evidence so far suggests that patient reporting of suspected adverse drug reactions has more potential benefits than drawbacks, and that evaluation of patient reporting systems is needed to provide further evidence.


This area is relatively under-researched and there remain several unanswered questions. We do not know enough about how patients make attributions of adverse effects of medications. Little work has been carried out to develop and evaluate ways of encouraging patients to tell prescribers about perceived problems with their medications, without either alarming them or causing doctors to become defensive, and of facilitating balanced discussions of adverse effects. More work is needed to find ways of helping patients to avoid making medication errors themselves. The new National Institute for Health and Clinical Excellence guideline on medicines adherence recommends that professionals should ask patients if they have any concerns about their medicines, including concerns about adverse effects [23]. Such an approach is more likely to yield information conducive to the identification of medication errors than a narrow focus on adherence.

Competing interests

None to declare.