Clinical Trials


Understanding clinical trials

Clinical trials explore whether a treatment is safe and effective

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Why clinical trials are important

They help us see what will work in medicine

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Types of clinical trials

Each type of trial has a different purpose

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Understanding clinical trials

A clinical trial is a particular type of research that explores whether a medical strategy, treatment or device is safe and effective for humans.


Involving patients, healthy volunteers or both, a clinical trial is one part of a long and careful research process. Clinical trials provide researchers with the opportunity to potentially find better treatments for others in the future, as well as offering hope for many people.

What do clinical trials do?

Clinical trials are used to help find out if a treatment:

Is safe to use

Has any side effects

Works better than a standard treatment

Helps make you feel better

Why clinical trials are important

Although all new drugs, treatments and devices are rigorously tested in the laboratory they must also go through clinical trials so more can be found out about their potential benefits or risks.


We need clinical trials to find out what does and doesn’t work in medicine and healthcare. A new treatment is not always better than existing treatments. Clinical trials are therefore very important as they can provide essential answers.

Why do people take part in clinical trials?

From a survey of 5,701 patients, the top perceived benefits were seen as:1

Advancing science and treatment
Helping to improve or save lives
Helping to improve my condition

1. Accessed June 2017.

Types of clinical trial

Clinical trials come in many different formats, these are called phases.


Each phase has a distinct purpose and helps researchers answer a variety of questions on safety, effectiveness and the right dose to use.

Phase one trials are used to test the safety of a new medicine and to identify any side effects. They are also used to calculate the right dose of the treatment to use. This part of the trial is known as “dose-ranging”. Dose-ranging can also be carried out in later phases of clinical trials.
A Phase one trial is the first time a new medicine is tested in humans and is usually carried out with a small group of healthy volunteers or sometimes patients.
Unfortunately not all clinical trials will be positive. Some of the studies will discover that the treatment being tested does not work, has worse side effects than existing treatments, or that it is no better than an existing treatments. It is important to remember that this kind of information is still useful for researchers and doctors and that it will help patients in the future.