What is a clinical trial?

Clinical trials assess new treatments, technologies or methods, whilst other research studies help better understand health and specific conditions.

A clinical trial compares the effects of 1 treatment with another. It may involve patients, healthy people, or both.

Testing a new medicine

All clinical trials of new medicines go through a series of phases to test whether they’re safe and whether they work.

The medicines will usually be tested against another treatment called a control.

This will either be a dummy treatment (a placebo) or a standard treatment already in use.

Phase 1 trials

A small number of people, who may be healthy volunteers, are given the medicine.

The drug is being trialled in human volunteers for the first time.

Researchers test for side effects and calculate what the right dose might be to use in treatment.

Researchers start with small doses and only increase the dose if the volunteers do not experience any side effects, or if they only experience minor side effects.

Phase 2 trials

The new medicine is tested on a larger group of people who are ill. This is to get a better idea of its effects in the short term.

Phase 3 trials

Carried out on medicines that have passed phases 1 and 2.

The medicine is tested in larger groups of people who are ill, and compared against an existing treatment or a placebo to see if it’s better in practice and if it has important side effects.

Trials often last a year or more and involve several thousand patients.

Phase 4 trials

The safety, side effects and effectiveness of the medicine continue to be studied while it’s being used in practice.

Not required for every medicine.

Only carried out on medicines that have passed all the previous stages and have been given marketing licences – a licence means the medicine is available on prescription.

Why join a clinical trial?

Clinical trials help doctors understand how to treat a particular illness. It may benefit you, or others like you, in the future.

If you take part in a clinical trial, you may be one of the first people to benefit from a new treatment.

But there’s also a chance that the new treatment turns out to be no better, or worse, than the standard treatment.

Will I get paid?

Some clinical trials offer payment, which can vary from hundreds to thousands of pounds depending on what’s involved and expected from you.

Some trials do not offer payment and just cover your travel expenses.

It’s important to find out about the inconvenience and risks involved before you sign up, and to carefully weigh up whether it’s worth it.

Bear in mind:

it can be time consuming – you may be expected to attend a number of screening and follow-up sessions, and some trials require you to stay overnight
there may be restrictions on what you can and cannot do – for example, you may be asked to not eat or not drink alcohol for a period of time
you may experience unknown side effects from the treatment