Patient rights in clinical trials: participation and withdrawal

What does voluntary participation in a clinical trial mean?

Voluntary participation means your decision to join a clinical trial must be made freely, individually, and without pressure that could push you to accept risks you would not otherwise accept. This means the decision has to originate from you alone. It must be uninfluenced by financial incentives that are disproportionate to the burden involved, and free from undue influences of any kind. The Charter of Fundamental Rights of the European Union recognises human dignity and the right to integrity of the person. It requires that any intervention in the field of biology and medicine — including research — cannot be performed without your free and informed consent^[1].

You have the right to refuse to take part in a trial. If you do agree to take part, you can still decline to continue or withdraw at any time and for any reason, without prejudice and without loss of future treatment. This protection exists precisely because clinical trials involve people who may be unwell, worried about their prognosis, or hopeful about access to a new treatment. Any of these circumstances could make a person feel obliged to agree even when they have doubts^[1]. The principle of voluntariness is therefore not a formality attached to the consent form. It is meant to actively protect you from situations in which your agreement might not reflect your genuine wishes^[2].

What must informed consent tell you before you agree to join?

Before you enrol, you have a right to fair information about all the possible benefits, risks, and burdens of taking part, the purpose of the trial, and the overall plan — the methods used, and the location and time required. You are entitled to know everything that is going to happen to you during the study^[1].

In practice, a member of the research team explains the trial in clear, understandable language, and you receive information both verbally and in writing. This process must give you the opportunity to ask questions and raise any concerns before you decide^[1].

Consent is not a single event tied to a signature. If new benefits, risks, or side effects are identified once the trial is under way, the research team must inform you, even if you have already signed the consent form. This ongoing duty reflects the fact that clinical trials are, by definition, conducted precisely because the full safety and efficacy profile of the intervention is not yet known. New findings can emerge at any stage, and you have the right to reconsider your participation in light of them^[1]. In the specific context of dermatology trials, informed consent must also be obtained before any procedure carried out solely to check whether you are eligible for a study — including, for example, stopping a medication to see how you respond. This matters because eligibility-screening procedures can themselves carry risk. The fact that a test is done "just to check" whether you qualify does not exempt it from the same consent standards that apply to the trial itself^[3].

What changes if part of the trial takes place at home rather than at a clinical site?

Clinical trials increasingly use procedures that take place outside the traditional trial site — for example, at your home — a model referred to as decentralisation. This shift raises new questions about how consent and safety oversight are managed when a researcher is not physically present. A European Commission recommendation paper, updated in October 2025, sets out considerations for the informed consent process in this context. These considerations include the informed consent interview, the use of a digital information leaflet, and how the informed consent signature is obtained^[4].

This document also covers how investigational medicinal products can be delivered directly to you and how trial-related procedures may be carried out at home. If your trial involves such elements, you should still receive the same substantive information as you would at a site visit, including an opportunity to ask questions, but delivered through remote means such as video calls, telephone consultations, or digital consent tools. The paper is explicitly stated not to be legally binding. Only the Court of Justice of the European Union can give an authoritative interpretation of the underlying law, and for trials running across more than one country, national requirements can still differ. For cross-border trials with decentralised elements, it is the sponsor's responsibility to check the national requirements and contact the national contact point of the relevant Member State if authorisation is needed^[4].

Can you withdraw from a clinical trial at any time, without giving a reason?

Yes. Once you have agreed to take part, you retain the right to decline further participation or withdraw at any time and for any reason, without prejudice and without loss of future treatment you would otherwise be entitled to^[1]. Recruited participants should be told at the outset that they can freely withdraw their consent at any point during the trial. Participants need to feel, from the outset, that agreeing to take part is not an irreversible commitment^[5].

Withdrawal of consent during a trial is not uncommon and can happen for several reasons: the treatment being tested does not seem to be working, side effects that are difficult to tolerate appear, follow-up visits become impossible to keep, or you simply change your mind about continuing. None of these reasons needs to be disclosed to the research team in detail. None of them needs to meet any particular threshold of seriousness. A research team member can also end your participation, independently of anything you have done, though this is a separate situation from your own decision to withdraw^[5].

A review of 114 consent forms from a US academic medical centre found that all of them included the required statement that withdrawal will not affect the care a participant receives. However, none of them explained to participants what the health consequences of withdrawing might actually be. About a quarter asked participants to complete an additional action, such as a visit or test, before withdrawal could be finalised. This is a general finding about consent-form practice rather than an EU rule, but it is a useful prompt: before you sign, it is reasonable to ask what, if anything, you would need to do to withdraw, and whether withdrawal could have any effect on your health monitoring^[6].

Can you withdraw from some procedures but still allow passive follow-up?

Withdrawal is not always all-or-nothing. You may be asked, or you may ask, to stop receiving the study treatment or attending study visits, while still allowing the research team to check your medical records passively for safety information. This distinction matters because trial results depend on complete follow-up. If many participants are lost to follow-up or fully withdraw, safety signals may go undetected, and the effectiveness of the treatment may be estimated inaccurately. In practical terms, this means that even a participant who no longer wishes to take the study drug or attend visits may still make a meaningful contribution to the trial's scientific validity simply by allowing minimal, passive checks on their outcomes^[7].

Your right to withdraw from all research procedures is not absolute in every ethical analysis. One view argues that, for minimal-risk study procedures such as passive data collection, the importance of upholding the principle of beneficence can outweigh individual autonomy concerns, and that a consent process which prospectively informs participants that passive follow-up will be mandatory — rather than optional — can be ethically justified. If this possibility was explained to you clearly before you enrolled, this approach holds that agreeing to it as a condition of participation does not violate your rights, even though it limits how completely you can withdraw. Other approaches may give more weight to your ability to refuse passive follow-up altogether; it is worth asking the research team how this is handled in your specific trial^[7].

What happens to your health data and samples if you withdraw?

Withdrawing from a trial does not automatically mean that every piece of information already collected about you disappears. Guidance on this topic distinguishes between data collected up to the point of withdrawal and any new data that would be collected afterwards. Data already gathered before you withdrew is typically retained and used in the trial's analysis, because removing it retroactively could distort the overall results. No new information about you should be collected once your withdrawal has taken effect, unless you have specifically agreed to some form of continued passive monitoring. The proportion of participants who withdraw consent is itself tracked as a quality indicator for randomised controlled trials, because it affects how much data remains available for analysis^[5].

What exactly happens to your previously collected data after you withdraw should be explained to you as part of the consent process, ideally before you agree to take part^[5]. If this was not made clear to you, or if you are unsure what will happen to your data specifically in your trial, you have the right to ask the research team directly and to receive a clear answer^[1].

How should a research team record and manage your withdrawal?

A 2025 project by the UK Clinical Research Collaboration's Registered Clinical Trials Unit Network, called PeRSEVERE, examined how trials units standardise the management of consent withdrawal and other changes to participation. The project's starting point was that changes to a participant's involvement — including partial and full withdrawal — need to be handled consistently. Your choices need to be respected and correctly reflected in how the trial continues to use, or stops using, information about you. The initiative reflects a recognition across multiple trials units that, without a standard approach, there is a risk of inconsistent practice between studies and even between sites within the same study. This inconsistency can create confusion both for participants and for the teams managing their data^[8].

For you as a participant, the practical implication is that when you tell the research team you wish to withdraw, or to change the extent of your participation, this should be recorded formally by the study team, not left as an informal conversation. If you are asked to confirm your withdrawal in writing or through a specific form, this is a normal part of that process rather than an attempt to discourage you from withdrawing. A clear, documented record of your decision also protects you, since it creates evidence of exactly what you agreed to stop, and from what date. This can help avoid any later disagreement about what was or was not communicated^[8].

What is expected of you while you remain a trial participant?

Taking part in a trial also carries some practical expectations, though these are not legal obligations in the way a professional's duties are. You are generally expected to follow the prescribed dosage and schedule for any study medication, since poor adherence can affect the reliability of the trial's results^[2].

• Report any unusual symptom or possible side effect to the research team promptly^[2];
• try to maintain your own health and avoid unnecessary risks while enrolled^[2];
• discuss any significant change in your health or daily routine with the trial team, as it may affect the trial's results^[2].

These expectations exist because a trial's scientific value depends on accurate, timely information from every participant. Unreported symptoms or missed visits can make it harder for researchers to draw reliable conclusions about safety and effectiveness. None of these expectations remove your right to withdraw. They describe what is asked of you only for as long as you choose to remain in the trial^[2].

Where can you get independent advice about participation or withdrawal?

Patients frequently need independent advice about whether to continue or discontinue participation in a trial. Patient organisations often do not have the resources to give this advice themselves, but they can point you towards services or contacts that can. This role — connecting patients with the right source of independent guidance, rather than acting as that source directly — reflects the fact that decisions about withdrawal can be highly personal and sometimes medically complex. They are best discussed with someone familiar with both the specific trial and your individual health situation^[2].

If you are already enrolled, your first point of contact for questions about withdrawal, or about what happens to your data if you withdraw, is the research team named in your consent documents. You do not need a reason to ask these questions, and asking them does not commit you to withdrawing^[1].

Summary

Your participation in a clinical trial rests on two connected rights: the right to agree freely, based on full and understandable information, and the right to stop at any point, for any reason, without it affecting the care you are otherwise entitled to. These rights do not disappear once you have signed a consent form — the research team must keep informing you of new information for as long as you are enrolled, and must respect your decision to withdraw fully or to limit your continued involvement.

Before agreeing to take part, it is reasonable to ask what would happen, practically, if you later decided to withdraw — including what would happen to data already collected. If you are already taking part and are considering withdrawal, you can raise this with the research team directly, and patient organisations may be able to point you towards further independent advice.

1. [1] Trial Participants' Roles & Rights: Trial Participants' Rights and Obligations (accessed 2 June 2026) — https://learning.eupati.eu/mod/page/view.php?id=345
2. [2] Participants' rights, responsibilities, organisations - EUPATI Toolbox (accessed 2 June 2026) — https://toolbox.eupati.eu/resources/participants-rights-responsibilities-organisations/
3. [3] Ehrenberger HE, Joshi TG. Dermatology Clinical Trials and Drug Development. Dermatology Nursing. 2003;15(5). Available from: — https://www.medscape.com/viewarticle/464022_4
4. [4] Recommendation paper on decentralised elements in clinical trials, Version 02 (accessed 2 June 2026) — https://health.ec.europa.eu/document/download/2ccc46bf-2739-4b9a-ab6b-6f425db78c61_en?filename=mp_decentralised-elements_clinical-trials_rec_en.pdf
5. [5] https://pmc.ncbi.nlm.nih.gov/articles/PMC3737004/
6. [6] https://pmc.ncbi.nlm.nih.gov/articles/PMC9527709/
7. [7] [Author(s) not listed in source excerpt]. Should Participants in Clinical Trials Be Able to Withdraw from Passive Follow-Up? PMID: 33463078. Available from: — https://pubmed.ncbi.nlm.nih.gov/33463078/
8. [8] https://pmc.ncbi.nlm.nih.gov/articles/PMC12476473/