About Clinical Trials

What are clinical trials?

The basic aim of a trial – whatever it tests – is to find out whether what is being tested is better than what is currently offered, and safe. On the UKCTG, the word “treatment” is used to cover all of the possible things that might be tested in a trial.

What sort of things do clinical trials test?

As set out above, researchers use clinical trials to test a wide range of ‘interventions,’ including, for example, drugs, devices and health education.

For example, researchers might design a trial to see how well a new vaccine prevents a certain disease from occurring, or how effective a new medicine is compared with the existing (‘standard’) treatment.

Sometimes researchers use trials to test how existing drugs work for new uses, or in combinations that haven’t yet been tried; or they might test whether giving a drug in a different way will reduce side effects in a specific group of patients; or whether a well known supplement, such as a vitamin or mineral, is an effective treatment for a certain illness.

Not all trials are drug trials, instead the research study might be based on a new medical device, or an intervention aimed at changing behaviour or lifestyle, such as a non-drug therapy or an educational programme.

Are clinical trials safe?

Yes, almost always. Large numbers of people take part in thousands of clinical trials in the UK every year, which safely study many different kinds of treatments.

Each trial is designed to keep risk to a minimum, those who take part are carefully assessed to ensure they are suitable and are monitored carefully throughout.

Rigorous processes – including review by an NHS Research Ethics Committee – protect your rights, dignity, safety and wellbeing if you take part in a clinical trial in the UK.

Before a trial starts, researchers should carry out a "systematic review" that compares information to date, to see that the trial they are planning is needed. Everyone involved with the trial, such as patients, health professionals, statisticians, trial managers and representatives from drug companies can then work together to design the best possible trial.

That said, there can be risks as well as benefits to joining a clinical trial. Before taking part, you should ask your doctor any questions to make sure you understand all that is involved. To find out more, see our page on what should I know before choosing to join a trial.

There are risks as well as benefits to clinical trials – but they are designed to keep risk to a minimum

Can anybody take part in a clinical trial?

Every clinical trial is different. When setting up trials, researchers create a set of guidelines, known as ‘eligibility criteria’, which determine who can and can’t take part.

For one trial, for example, you might only be eligible if you’re over a certain age and have blood pressure below a certain level. Or for another, you might be ineligible if you’re pregnant, to avoid risks to your unborn baby.

Before you take part in a trial, you may need tests to see if you are eligible – for example, to test your blood pressure.

There are many trials which also need healthy volunteers

Where do clinical trials take place?

A trial might take place at an NHS hospital or health centre, at a university or research institute, in the social care sector, or at a private-sector institution. If you’re thinking of getting involved, you should consider whether you will be able to travel there easily. For more on the practicalities of a trial, see our section on what you should know before choosing to join a trial.

What should I do next?

Read our section on why join a clinical trial and, if you’re interested, how to get involved.