What you should know about taking part in a clinical trial

If you’re thinking about taking part in a clinical trial you need to know about the possible benefits and risks. Learn about the questions you should ask before deciding, and what informed consent means.

Reasons to join a clinical trial

Clinical trials are essential for evaluating the effectiveness and safety of medicines, devices, services and interventions to help prevent, identify or treat illness and disease. It is through the research done on clinical trials that people gain access to better treatments. If more people take part in clinical trials, it may reduce the time it takes to make new interventions widely available.

By taking part in a clinical trial, you can contribute to the advancement of scientific knowledge. In some cases, your own health or that of others with the same disease or condition might improve.

If you are healthy

If you are healthy you can choose to participate in clinical trials:

  • to help others
  • to give back to the community
  • to contribute to improved health care
  • to help advance scientific knowledge
  • because you have a personal interest in the specific trial
  • because you have a friend or family member with the disease or condition.

If you have a disease or condition

If you have a disease or condition you can decide to participate in clinical trials to:

  • contribute to better understanding of your disease or condition
  • help find a better treatment or potential cure for your disease or condition
  • gain access to new interventions before they are widely available
  • receive extra support and attention from clinical trial staff who understand your disease or condition.

Potential benefits and risks

Volunteering to help improve the lives of family, friends or others is an extraordinary gesture of kindness. However, before participating in a clinical trial, think carefully about the demands on your time, and the possible risks and benefits.

Potential benefits

Along with helping to find better treatments, therapies and diagnostic tests, you can directly benefit from taking part in a clinical trial by:

  • being given a new intervention that may be better for your condition or that has fewer side effects than what you are receiving now
  • gaining access to the newest interventions before they are available to the general public
  • playing an active role in your own health care and gaining a greater understanding of your disease or condition
  • receiving advice, care and support from trained clinical staff who understand your disease or condition
  • monitoring your condition, care and treatment more closely
  • increasing understanding of how to best treat or manage a rare or difficult-to-treat condition.

There is no guarantee that you will receive any direct benefit from taking part in a trial.

Potential risks

While some clinical trials require minimal time and effort from participants, others require a major commitment and involve discomfort or pain.

Some possible risks of taking part in a clinical trial are that:

  • the new intervention in the clinical trial may not work for you
  • the new intervention may not be as effective as established interventions or standard care
  • there are unpleasant, serious or even life-threatening side effects
  • the need for extra treatment, tests, hospital visits or complicated medication requirements arising out of your participation in the trial (for example, you may need to keep a symptom diary, collect 24-hour urine specimens or wear a monitor overnight)
  • there are unanticipated risks due to limited use or testing of the intervention in humans – these will depend on the type and phase of the trial.

Researchers must describe the risks of a specific trial in detail as part of the process of informed consent.

Carefully consider the possible risks and benefits of taking part in a clinical trial, including:

  • what kind of harm may occur
  • how serious the harm may be
  • what the chance is of any harm occurring.

Planning your participation

If you are thinking of taking part in a clinical trial, find out as much as possible about the trial and your involvement in it. You can get this information from your doctor or healthcare professional, the research team, or the participant information and consent form.

When you discuss participation:

  • consider taking a family member or friend along for support and for help in asking questions or recording answers
  • plan what to ask ahead of time, but don't hesitate to ask any new questions that you think of while you're there
  • write down your questions ahead of time to make sure you remember to ask them all
  • write down or record the answers, so that you can look at them whenever you want
  • remember that you can ask the team running the trial extra questions at any time
  • remember that you can withdraw from the trial at any time and resume other treatment, if that is recommended by your doctor.

Questions to ask

Here are some suggested questions you may want to ask.

About the trial

  • What is the aim of the trial and how will it help people?
  • Has the intervention been tested before and, if so, what was the outcome?
  • Will the trial use a placebo (an inactive treatment), standard care or another established intervention as the control to compare with the new intervention?
  • Who is funding the trial?

Your involvement

  • How might this trial affect my daily life? How much of my time will you need?
  • What kinds of tests and experimental interventions will you use?
  • Will I have to complete questionnaires or keep a diary?
  • Will I need to spend time in hospital?
  • Will I need to take time off work or school?
  • Where are you doing the trial and will I have to travel to be part of it?
  • Will I be able to take my regular medications while participating in the trial?
  • How long is the trial expected to last? How long will I have to be part of it?
  • What will happen if I stop the trial intervention or leave the trial before it ends?
  • Who will be in charge of my care? Who can I contact for support and information during the trial? Will someone be available 24 hours a day?
  • How will my privacy be protected?


  • What are the risks of taking part in this trial? What are the possible side effects of the trial intervention?
  • How do the possible risks, side effects and benefits in the trial compare with my current treatment or care?
  • If one intervention proves to be more effective during the trial, will all participants be given access to it?


  • Who will pay for the experimental intervention?
  • Will I be paid to participate in the trial?
  • Will the trial cover my expenses?
  • If I live in a rural or remote area, will I be eligible for travel assistance?
  • If I experience complications arising from the trial, who is responsible for paying for any associated costs?

After the trial

  • What follow-up care is available after the trial?
  • How long will it be before you know the results of the trial?
  • How do I find out the results of the trial?
  • Will I have access to the experimental intervention after the trial if I wish to continue with it?

Informed consent

No one can enter you into a clinical trial if you don't want to take part.

If you are asked to take part, you are free to say yes or no at any time.

There is no pressure to enter a trial.

Everyone taking part in a clinical trial must give ‘informed consent’. If you are under 18, a parent or guardian, or other legally authorised person, has to give legal consent and you have to give your permission as well.

Informed consent is a decision, given voluntarily, to agree to a healthcare treatment, procedure or other intervention. It means that before you decided whether to take part or not, you:

  • considered information about the clinical trial and alternative options available
  • understood the benefits and risks of the clinical trial for the person who would be participating.

To help you decide whether or not to be part of a trial:

  • members of the research team will explain the trial to you
  • researchers will give you a participant information and consent form, that includes details about the research project such as its purpose, duration, required procedures, risks and potential benefits
  • ask about anything that is not clear to you or that you do not understand
  • take your time and talk it over with family and friends or your own doctor.

You will then decide whether or not to sign the consent document. Signing the consent form means that you agree to take part in the trial and understand what that will involve.

The consent form is not a contract, and you may withdraw from the trial at any time. If you do withdraw from a clinical trial, it will not affect your routine health care or your relationships with the researchers or your doctor.

Researchers must let you know if there are any changes to the trial or to the protocol. If this happens, you may need to give your consent again before proceeding with the trial.

Giving consent for another person

Some people are unable to give consent to participate in a clinical trial, such as:

  • those who are temporarily unable to give consent, including unconscious patients
  • those with
    • a severe cognitive impairment, including elderly patients with dementia
    • an intellectual disability
    • a mental illness
  • children who are not able to give consent.

In these circumstances, consent can be given by:

  • guardians
  • someone authorised by a court to act on behalf of the person who is not able to give informed consent
  • responsible family members.

People whose first language is not English and those with less severe cognitive impairment, intellectual disability or mental illness still need to provide their own informed consent. However, family members, or guardians, may be able to help them decide whether to participate in a clinical trial.


Date last updated:
  • About clinical trials