Safety in clinical trials

If you decide to take part in a clinical trial, you are protected in lots of ways:

  • The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) makes sure clinical trials meet high standards of practice and that all serious side effects are reported.
  • All clinical trials have to be approved by a research ethics committee. These are independent groups made up of a mixture of health professionals and non-medical people. They ensure patients are given all the information they need.
  • Data monitoring committees monitor the safety of a clinical trial and how well a treatment is working. They can stop a trial if it is causing harm to a person.
  • All clinical trials have some form of insurance to compensate patients in the unlikely event something goes wrong.

How safe are clinical trials?

Understandably, anyone who enters a clinical trial will want to know that it’s safe for them to do so. There are a number of ways people are protected before and during a trial.

Medicines and Healthcare products Regulatory Agency (MHRA)

The UK’s MHRA makes sure trials meet international standards of good practice, which are there to protect the people taking part. All serious side effects must be reported.

Research ethics committees

All research in the UK involving people, whether done in the NHS or the private sector, has to be approved by an ethics committee.

These are independent groups that put the rights, safety, dignity and well-being of research participants at the centre of their decision-making. They make sure that patients are fully informed, and check that any information given is clear and accurate. They also ensure that patients are compensated if anything goes wrong.

The research ethics committee looks at each research proposal and gives an opinion about the trial and whether the research is ethical.

The committees cover a local area and must be made up of a mix of health professionals and non-medical people. They often include patients, lawyers and members of the public. Having non-medical people is important as they can look at the trial from an ‘outsider’s’ point of view.

The research ethics committee is independent of research sponsors, funders and investigators. It checks that:

  • the researchers are qualified to do the trial
  • the trial is well planned
  • the likely benefits are greater than the possible risks
  • patients are recruited to the trial correctly.

Patients and members of the public are becoming more involved with research teams. They bring the patient’s perspective of illness and treatment, which can help the researcher’s understanding.

For example, they comment on the possibility of people wanting to participate in a trial and what aspects of the trial might put people off taking part.

Patients and members of the public can also suggest new areas for research and help to write information about clinical trials for the public.

Monitoring trials and stopping rules

Before a trial begins, a data monitoring committee is usually set up to monitor patient safety and the effectiveness of the treatment during the trial.

The data monitoring committee along with the research ethics committee can stop a trial if they are concerned that a new drug or treatment is causing harm to a person. For example, they can stop a trial if there are severe side effects. This is unlikely to happen in phase 3 or 4 trials because new drugs or treatments are well tested during phases 1 and 2.

Trials can also be stopped early if the results of the new treatment appear to be much better than the standard treatment. The new treatment can then be used instead of the standard treatment so that everyone in the trial can benefit from it.

Sometimes patients will then move from being in the control group, to the new treatment group.

If they see that it’s having serious effects and negative effects, they’ll pull you out of it. So you always have the option of stepping back from it.

Tom, clinical trial participant


The drugs used in clinical trials are made to the highest standards of purity and quality. Drug companies are insured so that if a patient is harmed by an unforeseen event due to the drug, compensation can be paid. It’s very rare for patients to be seriously harmed by trial drugs, although some may cause unpleasant side effects.

Trials funded by the Department of Health, the UK Medical Research Council or medical charities may not have this kind of insurance, but a payment would be made if something did go wrong.

All trials will have a legal sponsor. One of the sponsor’s roles is to make sure that there are arrangements, such as insurance, to protect those taking part against damage or loss.

However, individual NHS trusts are responsible for insuring themselves against harm caused by local trials. Research ethics committees will refuse approval for trials where there is no insurance or provision for compensation.

Back to Can and should I take part?