Clinical trials can involve testing new medicines, operations, ways to exercise, diets, vaccines, medical devices or more.

In Australia, participants in a clinical trial must fully understand all the facts about the trial before they can agree to take part. This is known as informed consent.

A group known as a human research ethics committee, which always has members of the public involved as well as researchers and doctors, must agree that a trial is ethical before it can go ahead.

Types of clinical trials

For medicines

Clinical trials of new medicines usually take place in phases.

• Phase I clinical trials involve giving a group of 20 to 80 healthy volunteers the drug to check that it doesn’t harm them.
• Phase II clinical trials involve giving a few hundred people the new medicine to check that it is safe and that it might work for more people.
• Phase III clinical trials involve giving a few hundred or a few thousand people the new medicine to see if it really does work and to see what side effects it has.

A phase III clinical trial might involve comparing the new test or treatment to the standard test or treatment, or to no test or treatment at all.

For lifestyle advice, tests and medical devices

These types of clinical trials are similar to phase III trials for medicines. They usually involve comparing a new piece of advice (or test or device) with nothing, or with the usual advice (or test or device). The aim is to find out whether or not the new approach is better than the old.

Why are clinical trials needed?

Clinical trials allow researchers to work out whether a new test or treatment is both safe and effective. It also allows researchers to assess who should be offered the new test or treatment, and who should not.

Benefits and risks of participating in clinical trials

You might be asked to take part in a clinical trial. If so, the benefits may include:

• having the new test or treatment before others
• closer monitoring of your condition than might usually happen
• knowing that you are helping others by doing so

There are also downsides, which may include:

• unpleasant side effects of the test or treatment
• the need for extra treatment, tests or hospital visits than might usually happen
• the test or treatment might not be helpful for you

To find out more about clinical trials, visit the Australian Clinical Trials website. Or, if you are specifically looking for information about cancer trials, visit Cancer Australia's Australian cancer trials website.