If you have ever wondered whether you could join a clinical trial, you are not alone. One of the most common questions people have is: “Would I even be eligible?” The answer depends on a set of rules called eligibility criteria. This article explains what those rules are, why they exist, and what you can do if you want to take part.
What Are Eligibility Criteria?
Every clinical trial has a list of conditions that a person must meet before they can join. These are called eligibility criteria, and they are split into two types:
- Inclusion criteria – the things you must have or be (for example, a certain age range, or a specific diagnosis)
- Exclusion criteria – the things that would stop you from joining (for example, taking a certain medicine, or being pregnant)
These rules are not there to make things difficult. They exist to keep participants safe and to make sure the trial produces reliable results. For more on how clinical trials are overseen and regulated in the UK, the NHS clinical trials page gives a clear overview.
Why Do These Rules Exist?
To Keep People Safe
Researchers need to make sure the treatment being tested is unlikely to cause harm to the people involved. For example, a new medicine might not have been tested in people with certain heart conditions, so those people would be excluded until more is known.
To Get Accurate Results
If a trial is testing a treatment for asthma, it makes sense to only include people who actually have asthma. If the group of participants is too mixed, it becomes harder to tell whether the treatment is working.
To Find the Right People
Some trials are looking for people at a specific stage of a condition, or people who have not responded to existing treatments. This means the rules can be quite detailed, but they are always there for a good reason.
Common Examples of Inclusion and Exclusion Criteria
The table below shows some typical examples of the kinds of criteria you might see in a clinical trial.
| Type | Example |
| Inclusion | Aged between 18 and 75 |
| Inclusion | Diagnosed with the condition being studied |
| Inclusion | Not currently taking certain medications |
| Exclusion | Pregnant or breastfeeding |
| Exclusion | Have a serious liver or kidney condition |
| Exclusion | Have taken part in another trial in the last 30 days |
These are just examples. Every trial is different, and the criteria will vary depending on what is being studied.
How Does the Selection Process Work?
Step 1: You Express Interest
The first step is to register your interest in a trial. You can do this by viewing our current trials and filling in an enquiry form for the condition that applies to you.
Step 2: A Pre-Screening Call
A member of the research team will usually get in touch to ask you some basic questions. This helps to check whether you are likely to meet the main criteria before you come in for a visit.
Step 3: A Screening Visit
If the pre-screening goes well, you will be invited to a screening visit at the clinic. This is a more detailed assessment where the team checks whether you meet all the criteria for that specific trial. To understand what to expect, read our article on what happens at a screening visit.
Step 4: Confirmation
After the screening visit, the team will let you know whether you are eligible. If you are, they will explain the next steps clearly before you make any decisions.
What If You Are Not Eligible for One Trial?
Not being eligible for one trial does not mean you cannot take part in any trial. Research teams understand this is disappointing, and a good team will let you know if there are other studies you might qualify for.
At 4MCS, we run trials across a wide range of conditions, including asthma, atrial fibrillation, psoriasis, migraine, and more. If one trial is not right for you, there may be another that is. You can find out more about how to take part in clinical research in the UK on our website.
It is also worth noting that eligibility criteria can change over the course of a research programme. A trial that you did not qualify for today may have updated its criteria in the future.
What Happens After You Are Accepted?
Once you are confirmed as eligible, the research team will walk you through everything. You will receive a detailed information sheet about the trial, and you will have plenty of time to ask questions before you agree to take part. This process is called informed consent, and it is a legal requirement for every clinical trial in the UK.
You are never under any pressure to join, and you can withdraw at any time without it affecting your medical care.
Is There Any Payment?
Trials at 4MCS do not pay participants, but travel expenses are covered. Many people find that the real benefits come from accessing new treatments, receiving regular monitoring from a specialist team, and knowing that their involvement could help others in the future. Our article on the value of joining a clinical trial goes into more detail on this.
Ready to Find Out If You Are Eligible?
The only way to know for certain whether you qualify for a trial is to get in touch and go through the screening process. Our team is friendly and experienced, and they will be straightforward with you about what to expect at every stage.
View our current trials to see which studies are open and take the first step towards finding out whether you are eligible.
