The effects of medications are not completely known when a drug is first licensed for use by the general population. Important side effects might only become apparent when the drug has been used in very large numbers of patients, or for prolonged periods of time. Some effects might not have been seen because they happen more often in people who are unlikely to be included in randomised trials, such as people who take a lot of other medication, or who have several illnesses at the same time. The natural spread of age and gender are not always evenly represented in trials, so information on drug effectiveness and side effects might be sparse for older age groups and, sometimes, women. Additionally, side effects of drugs such as heart attack and stroke are sometimes referred to as “rare” and the numbers of people in randomised trials are too small for these “rare” effects to show up.

In pharmacoepidemiology we study these effects in large groups of patients to give us a better idea of the overall balance of risks and benefits for a medication in the whole population. Not all effects are harmful; sometimes we might also be interested in finding out about the unintended benefits of a drug. Using primary care and linked electronic health records, we have been investigating these effects for many years, as well as developing better methodologies for this kind of study. Some of our past work includes examining the risk of stroke and myocardial infarction in patients with and without dementia who use anti-psychotics, the association between MMR vaccine and autism, co-prescribing of PPIs (drugs used to treat stomach acid) and drugs which prevent blood clots on risk of heart attack and stroke, and also the risk of cancer in users of angiotensin receptor blockers (drugs used to treat high blood pressure).


We have ongoing interests in improving methodology for pharmacoepidemiology, including

Disease Areas

Although we work on a broad range of drugs and diseases, some key areas of current focus are:


We offer training courses in pharmacoepidemiology