Clinical Trials FAQ — 73 Questions Answered

A clinical trial is a research study involving human volunteers that tests new treatments, drugs, medical devices, or new ways of using existing treatments. Trials are carefully designed, reviewed by ethics committees, and approved by regulators before participants are enrolled. They are the primary way medicine advances — every treatment your doctor prescribes today was once tested in a clinical trial.

Phase 1 tests safety and dosage in 20–100 people, often healthy volunteers.
Phase 2 tests effectiveness and side effects in 100–300 patients.
Phase 3 compares the new treatment to standard care in hundreds to thousands of patients.
Phase 4 monitors long-term effects after regulatory approval.

All clinical trials in the UK must follow strict ethical and regulatory guidelines overseen by the MHRA and NHS Research Ethics Committees. Before joining, you go through an informed consent process explaining risks, benefits, and what participation involves. You can leave at any time. However, some risk always exists — these are clearly explained before you agree.

Informed consent is the process where the research team explains the trial's purpose, procedures, risks, benefits, and your rights before you agree to take part. You receive a written information sheet and have time to ask questions. Informed consent is not a contract — you can withdraw at any time, for any reason, without affecting your regular medical care.

Yes. You have the absolute right to withdraw from any clinical trial at any time, without giving a reason, and without affecting your usual medical care. The research team will typically ask you to come in for a final safety check-up.

A placebo is an inactive treatment that looks identical to the real one. It is used in some trials to help determine whether the new treatment actually works. Not all trials use placebos — many compare a new treatment against the current standard of care instead.

In randomised trials, you may receive either the new treatment or the control (standard care or placebo). You will be told before joining whether the trial involves randomisation and placebos. In open-label trials, everyone receives the real treatment.

Randomisation means you are assigned by chance to receive one of the trial treatments — like flipping a coin. Neither you nor your doctor chooses which group you are in. This helps ensure the results are fair and unbiased.

In a double-blind trial, neither you nor the research team know which treatment you are receiving. This prevents bias in how symptoms are reported and assessed. An independent team monitors safety throughout and can unblind your treatment if medically necessary.

These are the rules that determine who can and cannot join a trial. Inclusion criteria might specify age range, condition type, or disease stage. Exclusion criteria might rule out certain medications, pregnancies, or other health conditions. These criteria protect participants and ensure the trial answers its research question properly.

Benefits: Access to new treatments before they are widely available, close monitoring by specialist medical teams, and the knowledge that you are helping advance medical science.
Risks: Unknown side effects, the treatment not working, more frequent hospital visits, and the possibility of receiving a placebo. All known risks are explained during the informed consent process.

A screening visit typically involves a physical examination, blood and urine tests, review of your medical history and current medications, and a discussion of the trial protocol. The team checks whether you meet eligibility criteria. It usually takes 1–3 hours.

It depends on the trial. Some conditions may exclude you for safety, but many trials welcome participants with common comorbidities like diabetes or high blood pressure. The eligibility criteria specify what is and isn't allowed. When in doubt, contact the research team.

Yes. Clinical trials for children exist and are essential for developing safe and effective paediatric treatments. They follow additional ethical safeguards and require parental or guardian consent. Children's trials are reviewed by specialist paediatric ethics committees.

Yes, and they are increasingly encouraged to do so. Many conditions are more common in older adults, so trials need older participants. Some trials specifically target over-65s. Age alone is rarely an exclusion criterion — your overall health matters more.

Most clinical trials exclude women who are pregnant or breastfeeding due to potential risks to the baby. However, some trials specifically study pregnancy-related conditions with extra safety monitoring.

Not always. Some trials accept self-referrals — you can contact the research site directly. Others require a referral from your specialist or GP. The trial listing will usually specify how to get involved.

It depends on the trial. Some allow you to continue current medications alongside the trial treatment. Others may require you to stop or change certain medications. This is specified in the eligibility criteria and discussed during screening.

Duration varies widely. Phase 1 studies may last a few weeks. Phase 2 and 3 trials can run months to several years. The expected duration is always explained during the informed consent process before you agree.

It depends on the trial. Phase 1 healthy volunteer studies often involve overnight stays at a clinical research unit. Most later-phase patient trials are outpatient — you visit the clinic for appointments but go home the same day.

This varies widely. Some trials require weekly visits; others need only a few over several months. Phase 1 studies may involve a concentrated period of visits, while Phase 3 trials often spread visits over 6–24 months. The schedule is always explained before you consent.

You are monitored closely throughout the trial and can report any symptoms to the research team at any time. Serious side effects are reported to the regulatory authorities. You can withdraw if you experience unacceptable side effects.

The data is analysed and results are published. You will be told what treatment you received and the overall findings. If the new treatment worked for you, your doctor will discuss ongoing access options, which may include continued treatment or returning to standard care.

These are clinical trials (usually Phase 1 or bioequivalence) that need healthy volunteers. Participants are compensated for their time and any inconvenience. Studies typically involve a short stay at a clinical research unit, plus follow-up visits.

Phase 1 healthy volunteer studies and bioequivalence trials typically offer compensation of £500–£3,000+ for your time and inconvenience. Later-phase trials for patients with specific conditions usually do not pay, but your travel costs may be reimbursed. TrialConnect clearly labels compensated studies.

Most paid studies require healthy adults aged 18–55. Specific requirements vary — some studies need particular demographics, non-smokers, or specific BMIs. Each study listing includes its eligibility criteria.

Compensation typically ranges from £500 to £3,000+ per study, depending on length of stay, number of visits, and study type. Phase 1 studies tend to pay more than bioequivalence studies.

Paid research studies follow the same strict safety and ethical guidelines as all UK clinical trials. Phase 1 units have 24/7 medical supervision, and all studies are approved by ethics committees and the MHRA. You undergo thorough health screening before being accepted.

You stay in a comfortable clinical research unit with private rooms, meals provided, WiFi, and entertainment. Medical staff monitor you around the clock. You give regular blood samples and may have vital signs checked. Most units have lounges, TVs, and games consoles.

Yes, but there is usually a waiting period between studies — typically 30–90 days — to ensure the previous study drug has fully cleared your system. The research team will advise on the required gap.

UK clinical trials are reviewed by NHS Research Ethics Committees (RECs) and authorised by the Medicines and Healthcare products Regulatory Agency (MHRA). The Health Research Authority (HRA) provides overall governance. No trial can start without ethical approval and regulatory clearance.

The Medicines and Healthcare products Regulatory Agency (MHRA) is the UK government body responsible for ensuring that medicines and medical devices are safe and effective. It authorises clinical trials of investigational medicinal products and monitors safety throughout.

A CTA is the regulatory approval required before a clinical trial of an investigational medicinal product can begin in the UK. It is issued by the MHRA after reviewing the trial protocol, safety data, and manufacturing information.

The National Institute for Health and Care Research (NIHR) funds, supports, and delivers health and care research in England. It runs the NIHR Clinical Research Network which helps deliver trials across NHS hospitals, GP practices, and community settings. The NIHR is the biggest funder of clinical trials in the UK after the pharmaceutical industry.

NHS hospitals and GP practices host clinical trials as part of routine care. Your NHS consultant may invite you to join a relevant trial, or you can search TrialConnect to find NHS-run trials near you. NHS trials follow the same strict ethical and safety standards as industry-funded trials.

Clinical trials are funded by pharmaceutical companies, biotech firms, the NHS, the NIHR, medical charities (like Cancer Research UK), and academic institutions. The funding source is always disclosed in the trial information.

No. Being in a clinical trial does not affect your right to receive standard NHS care. If the trial treatment does not work for you, you can return to standard treatment. The trial team and your NHS care team work together.

A biomarker is a measurable indicator of a biological state or condition — for example, a gene mutation (like BRCA1), a protein level (like PSA), or a blood test result (like HbA1c). Many clinical trials now use biomarkers to match patients to the most appropriate treatment.

Personalised medicine uses information about your genes, biomarkers, and individual characteristics to select the treatment most likely to work for you. Many modern clinical trials — especially in cancer — use this approach to match patients to targeted therapies.

Immunotherapy is a treatment that helps your immune system recognise and fight disease. It is used in many cancers (like melanoma, lung cancer, and lymphoma) and some autoimmune conditions. Many clinical trials are currently testing new immunotherapy approaches.

Gene therapy involves modifying or replacing genes to treat or prevent disease. It is being studied in clinical trials for conditions like sickle cell disease, haemophilia, and certain cancers. Gene therapy trials follow additional safety oversight.

CAR-T cell therapy is a treatment where your own immune T-cells are collected, genetically modified to recognise cancer cells, and then infused back. It is approved for some blood cancers and being studied in clinical trials for many other conditions.

An adverse event is any unwanted medical occurrence during a trial, whether or not it is related to the treatment. All adverse events are recorded and monitored. Serious adverse events are reported to the regulatory authorities and ethics committees within strict timelines.

Yes. Clinical trial results are published in scientific journals, on ClinicalTrials.gov, and often on the sponsor's website. In the UK and EU, there are legal requirements for publishing results within certain timeframes. You can ask the research team about the results of your trial.

Usually yes. The research team will ask your permission to inform your GP so your regular care is coordinated with the trial. This helps avoid conflicts with any medications your GP is managing.

No. Many trials run at community hospitals, local research centres, and GP practices across the UK. Some involve home visits or remote monitoring. TrialConnect shows trial sites near your location across 32 UK cities.

Your personal data is protected under UK GDPR and the Data Protection Act 2018. Trial data is anonymised — your identity is replaced with a code number. Only the research team can link the code to you. Data is stored securely and shared only as required by law.

A protocol is the detailed plan for the trial. It describes the treatment being studied, who can participate, what tests and procedures will be done, how data will be collected, and how long the trial will last. The protocol is approved before the trial starts.

Consider your condition, current treatment, how much time you can commit, and how far you can travel. Read the eligibility criteria carefully. Most importantly, discuss it with your healthcare team — they can help you weigh the potential benefits and risks for your specific situation.

An ADC is a targeted cancer therapy that links a monoclonal antibody to a chemotherapy drug. The antibody delivers the chemo directly to cancer cells, sparing healthy tissue. Examples include Enhertu (breast cancer) and Padcev (bladder cancer). Several ADC clinical trials are active in the UK.

Bispecific antibodies are engineered proteins that simultaneously target two different proteins — for example, binding both a cancer cell and an immune cell to trigger an immune attack. They are being tested in blood cancers, solid tumours, and inflammatory conditions. Teclistamab (myeloma) is an approved example.

Checkpoint inhibitors are immunotherapy drugs that release the "brakes" on your immune system, allowing it to recognise and attack cancer cells. Drugs like Pembrolizumab (Keytruda), Nivolumab (Opdivo), and Atezolizumab (Tecentriq) have transformed cancer treatment. Many trials test new checkpoint inhibitors or combinations.

CRISPR is a revolutionary gene-editing technology that can precisely modify DNA. In clinical trials, it is being used to treat genetic blood disorders (sickle cell disease, beta-thalassaemia), certain cancers, and inherited eye conditions. Casgevy, the first CRISPR therapy, was approved for sickle cell disease in 2023.

mRNA technology (used in COVID vaccines) is now being tested for cancer treatment, infectious diseases, and rare genetic conditions. Personalised mRNA cancer vaccines create a custom immune response based on your tumour's unique mutations. Several UK trials are actively recruiting.

PARP inhibitors (like Olaparib, Niraparib) block a DNA repair pathway in cancer cells. They are particularly effective in cancers with BRCA mutations or other DNA repair defects — especially ovarian, breast, prostate, and pancreatic cancer. Many PARP inhibitor trials are available in the UK.

Cell therapy involves transplanting human cells (like stem cells or immune cells) to treat disease. Gene therapy modifies genes to treat or prevent conditions. Together, they represent a new wave of treatments for cancer, blood disorders, inherited diseases, and neurological conditions. The UK is a world leader in cell and gene therapy research.

Targeted therapies are drugs that specifically attack cancer cells with certain genetic mutations or proteins, while largely sparing healthy cells. Examples include EGFR inhibitors for lung cancer, BRAF inhibitors for melanoma, and HER2-targeted drugs for breast cancer. Most targeted therapy trials require biomarker testing.

TKIs are a type of targeted therapy that blocks enzymes (kinases) involved in cancer cell growth and blood vessel formation. They are taken as tablets and used in kidney cancer, liver cancer, thyroid cancer, and leukaemia. Many newer-generation TKI trials are available.

Tumour-agnostic therapies treat cancer based on its genetic or molecular features rather than where it started in the body. For example, Pembrolizumab is approved for any MSI-H tumour regardless of cancer type, and Larotrectinib targets NTRK fusions in any solid tumour. Clinical trials continue to expand this approach.

Absolutely, and they are strongly encouraged to do so. Historically, ethnic minorities have been underrepresented in clinical trials, which means treatments may be less well-studied for these populations. The NIHR and pharma industry are actively working to improve diversity in UK clinical trials.

Yes. While informed consent documents are typically in English, many research teams can provide translators or translated materials. The NHS has a legal duty to provide accessible services. Ask the research team about language support when you contact them.

In most cases, yes. Disabilities alone are rarely exclusion criteria. Research sites must make reasonable adjustments under the Equality Act 2010. Contact the research team to discuss any accessibility needs.

Yes. The NHS is one of the largest clinical trial hosts in the world. Many trials are available through your NHS consultant or GP. Participating in an NHS clinical trial does not cost you anything — the trial covers all related medical expenses.

Yes. You can participate in a trial at any UK site where you meet the eligibility criteria. Some trials reimburse travel costs. TrialConnect covers 32 UK cities — search by location to find trials near you or where you are willing to travel to.

You can withdraw at any time without penalty. The research team will arrange a final safety check and discuss transitioning back to standard care. Your decision will not affect your NHS treatment or relationship with your doctors.

Yes. Veterans have the same access to clinical trials as any UK resident. Some trials specifically target conditions more common in veterans, such as PTSD, traumatic brain injury, and chronic pain. Contact the research team directly or ask your NHS provider.

Yes. Clinical trials run across all four UK nations. TrialConnect covers trial sites in Scotland (Glasgow, Edinburgh, Aberdeen, Dundee), Wales (Cardiff, Swansea), and Northern Ireland (Belfast), plus many English cities. Search by location to find trials near you.

TrialConnect is a free clinical trial search platform that helps patients, healthy volunteers, and healthcare professionals find actively recruiting trials. It indexes data from ClinicalTrials.gov and provides plain-English summaries, smart matching, and direct contact details for trial sites.

Yes, completely. Searching, browsing, and viewing trial details costs nothing. No account is needed. TrialConnect will always be free for patients and clinicians.

All trial data is sourced from ClinicalTrials.gov, the US National Library of Medicine's registry of clinical studies. It contains over 475,000 studies from 220 countries. Data is updated daily.

No. Your searches stay in your browser. TrialConnect does not track, store, or share any personal health information. No account or registration is required.

TrialConnect's Smart Matcher is an interactive tool that asks about your condition, biomarkers, treatment history, and location. It then searches ClinicalTrials.gov for trials matching your specific profile and ranks them by relevance. Try the Smart Matcher →

Each trial card on TrialConnect includes contact details for the research site or sponsor — usually a phone number and email. Click the contact links to get in touch directly. No intermediary is involved.