What is a clinical trial?

A study in people that tests whether a treatment, device, test or way of delivering care works, and how safe it is. Every medicine you have ever taken existed because people volunteered for one. Trials follow a written protocol that says exactly who can join, what will happen and what is being measured, and that protocol is reviewed by an independent ethics committee before anyone is approached.

Are clinical trials safe?

They are closely watched, which is not the same as risk free. Participants are monitored far more often than in ordinary care, an independent committee reviews the safety data as the trial runs and can stop it early, and you can withdraw at any point without giving a reason and without affecting your normal care. The honest summary is that a trial carries real uncertainty, because the point is that nobody yet knows the answer, and that uncertainty is watched more carefully than almost anything else in medicine.

Is a clinical trial a last resort?

No, and this is the most common misunderstanding. Trials run at every stage, including first treatments, prevention, screening and simple things like which of two standard drugs is better. Some of the most important trials ever run compared two treatments that were both already in normal use. Asking about a trial early keeps more of them open to you, because eligibility rules often exclude people who have already tried several other treatments.

Do you get paid for a clinical trial?

It depends on the study. Healthy volunteer studies, often phase 1, usually pay for time and inconvenience. Trials in people who have the condition being treated usually do not pay a fee, but commonly reimburse travel, parking and sometimes lost earnings, and the study treatment and study tests are normally free. Payment large enough to make you ignore the risks would itself be an ethical problem, so an ethics committee reviews the amount.

What is a placebo, and will I get one instead of treatment?

A placebo is a dummy with no active ingredient, used so that neither you nor the researchers can tell who got what, which stops expectation from bending the result. In most trials where an effective treatment already exists, you would not be left with nothing: the comparison is usually the current standard treatment, or the standard treatment plus either the new drug or a placebo. The consent form must say exactly which design is being used, and it is a fair question to ask before you sign.

Who decides whether I am eligible?

The study team, against the written protocol, after screening tests. A registry listing tells you the broad criteria, such as an age range or a diagnosis, but the fine detail decides most cases: recent test results, other conditions, and medicines you already take. This is why a search is a starting point and not an answer, and why your own doctor should see anything you are considering, since they know what else you are being treated for.

Can I leave a trial once I have started?

Yes, at any time, without giving a reason. Consent in a trial is ongoing rather than a signature you gave once. Leaving does not affect the care you get normally, and the team should offer a final check-up so that anything started during the study is followed up properly.

Where do the listings on this page come from?

From ClinicalTrials.gov, the public registry run by the US National Library of Medicine, which lists studies from many countries. We summarize the entries and link to the official record for each one. We do not run studies, we are not paid by any sponsor to recruit, and appearing in this search is not a recommendation of a study.

Clinical trials, explained

Most people hear the words and think last resort. Trials run at every stage of care, including prevention and first treatments. Here is what one actually involves, what to ask before you agree to anything, and how to see what is open near you.

4phases, and each one answers a different question

Anytime you like, you can leave a study you joined

0studies are run by us. We explain them and link to the record

Search open studies

This searches ClinicalTrials.gov, the public registry, for studies that are recruiting or about to. A listing tells you the broad criteria. Whether you are eligible is decided by the study team after screening, so treat this as a starting point.

What the phases mean

The phase tells you what question the study is asking, which is the fastest way to understand what joining it would involve.

Phase 1

A small group, often 20 to 100 people

Is it safe, and at what dose? Sometimes healthy volunteers, sometimes patients when the treatment is too strong for healthy people.

Phase 2

A few hundred people with the condition

Does it look like it works, and what are the side effects? Many treatments stop here.

Phase 3

Hundreds to thousands, often across many countries

Is it better than what we already use? This is the stage that decides whether regulators approve it.

Phase 4

People using an approved treatment

What shows up once it is in wide use, including rarer effects that a trial of 3,000 people could never see.

What to ask before you agree

Consent is a conversation, not a signature. Print these, or take them on your phone. A good study team will be glad you asked.

Question 1

What is being tested, and what would I be getting that I would not get otherwise?

Question 2

What is the alternative arm? If there is a placebo, will I still get the standard treatment alongside it?

Question 3

How much of my time does this take, and for how many months?

Question 4

Which costs are covered, and which are mine? Travel and parking included.

Question 5

What happens if I feel worse, or want to stop halfway?

Question 6

Who do I call at 2am if something goes wrong?

Question 7

Will I be told what the study found, and will I be able to keep the treatment if it works?

Where we stand

We do not run studies, screen anyone, or enroll anyone. No sponsor pays us to find participants, and nothing here is influenced by who is recruiting. What we do is explain how trials work and put the public registry in front of you, because the barrier for most people is not willingness, it is that nobody ever explained it.

Take anything you find to the doctor who treats you. Eligibility usually turns on your other conditions and your current medicines, which a search cannot see.

Before you look

Walking in with your own numbers changes the conversation, in a trial or in a clinic.

Prepare for the appointment Read your blood test Keep your medication list Your free health record Ask a doctor in writing

Common questions

Health education, not medical advice. This page explains how studies work in general. It cannot tell you whether a particular study is right for you, and it is not a substitute for the doctor who treats you.