A beginner’s guide to pharmacovigilance

All of us will take medicines at some point in our lives. Pharmacovigilance is all about the safer and more effective use of medicines for everyone, young and old. It covers everything to do with noticing, assessing, understanding, managing and preventing adverse effects of medicines for individuals and populations.

Medicines cure, but they can also harm

Medicines have brought enormous benefits, but no medicine is 100% safe for all people in all situations. While some medicines can cause severe or even fatal adverse drug reactions, most have predominantly beneficial effects for most people - even while they may cause occasional minor harm (such as a headache, rash or tiredness). 

Every time a treatment decision is made, the prescriber and patient must decide if the benefits are sufficient to accept the possibility of discomfort or harm, which may already be known and recorded on the patient leaflet. Sometimes there is unexpected minor or serious harm. This is why watching and reporting are so important: the more we know about what patients have experienced, the better informed we are to prevent harm in the future. The risks of vaccines causing harm are much lower than for medicines, but monitoring is still necessary.

‘Telling your doctor or pharmacist about adverse effects will help make drug use safer for everyone.’ 

How do medicines cause harm?

You may ask why it is that medicines cause harm at all. Medicines are a powerful, usually chemical or biological invasion of the body; that is why they can cure diseases but also why they sometimes cause damage.

We get to know about many of the benefits and harms that any medicine can cause when it is tested in clinical trials. These involve only a few hundred or thousand carefully selected people, so they do not represent the whole population of patients (maybe millions) who will eventually use the drug. It is only after it has been used by large numbers of patients over a longer period of time that more of its effects become clear, especially effects that are rare. Reporting of rare effects is particularly important in characterising the safety profile of a drug.

It is also the case that different people react differently to medicines, because everyone has different risk factors – relating to genetics, other diseases and medication, allergies, social conditions, psychology and so on. We need to know what it is that makes every patient vulnerable to harm; when harm occurs, it needs to be added to the body of knowledge that will influence how medicines are used in the future.

How do we reduce the risk of harm from medicines?

Wise therapeutic decisions, which give patients the greatest benefits with the least risk, must be made jointly by health providers and patients. 

A patient must understand, anticipate and recognise the known negative side effects of a drug; there must be a plan for when they first appear, and agreed action taken. The first essential step is likely to be returning to report the problem to the prescriber.

Taking the drug as prescribed, finishing the course, avoiding interactions with other foods or drugs – in other words adherence to the prescribing guidelines – all help to reduce the possibility of harm.

Nevertheless, we cannot eliminate the risk of harm completely. We must be prepared for occasional mild adverse side effects and be alert if there is any indication at all of potentially more serious ones. In that case, urgent action may be necessary.

Watching for safer medicines

Understanding patients’ experiences of treatment, and especially the harm that they may suffer, is an important aspect of patient care and public health. Recognising, recording and reporting adverse effects – as well as lack of effect and even unexpected benefits – will help us improve treatment and prevent harm for other patients in the future.

As patients, we can all report the effects of treatment to our doctor or pharmacist, especially harmful effects (such as a medicine causing diarrhoea or not working at all). When we tell them about a problem, they should discuss it with us, diagnose the cause of the problem and agree with us what needs to be done. Action could include changing the dose or stopping the drug and trying an alternative.

Medicines may have effects in many aspects of patients’ lives, not only in relation to their specific impact on disease. Adverse effects, even mild ones, may negatively impact patients’ work or lifestyle (by making them drowsy and unable to drive, for example). Patients may assess benefit and harm in ways very different from professionals. Information about these aspects of therapy is critical to a full understanding of patients’ experiences, but they are beyond the bounds of most current medical record-keeping or reporting.

Last modified on: November 10, 2020