How to Find Clinical Trials and Check Your Eligibility

The most direct way to find a clinical trial is through ClinicalTrials.gov, the largest public registry of studies worldwide, where you can search by condition, location, and treatment type and then read each trial’s eligibility criteria before reaching out. But the registry is only one piece of the puzzle. Your own doctor, hospital research teams, disease-specific advocacy organizations, and newer digital matching tools all play a role in connecting you to a trial that fits your medical profile. Understanding how eligibility works and what to expect from the process can save you weeks of confusion and make the difference between a dead end and a genuine treatment option.

Starting With ClinicalTrials.gov

ClinicalTrials.gov is the single largest database of clinical studies and is maintained by the U.S. National Library of Medicine. It lists trials from around the world, including those funded by government agencies, pharmaceutical companies, and academic institutions. The database provides structured information about each study’s purpose, design, locations, and results when available.¹ You can search by disease or condition, by drug or intervention name, or by geographic location. Each listing includes a set of inclusion and exclusion criteria that spell out who can and cannot enroll.

That said, the registry has some limitations worth knowing about. An analysis comparing ClinicalTrials.gov to a commercial trial database found that the commercial source captured about 31% more trials in several major disease areas, including breast cancer, lung cancer, type 2 diabetes, and pain.² Not every trial worldwide gets registered on ClinicalTrials.gov, and some listings may have outdated enrollment status. So while it is the best starting point, it should not be your only stop.

Another practical issue is readability. A study evaluating how patient-friendly the registry’s listings actually are found that brief titles and summaries scored only about half of what researchers considered the best possible patient-focus score.³ In plain terms, many trial listings are written for other researchers, not for patients. If you encounter dense medical jargon in a listing, that does not mean the trial is not relevant to you. It means you may need help interpreting it, which is where your doctor or a patient navigator comes in.

How Eligibility Criteria Actually Work

Every clinical trial has two lists: inclusion criteria (what you need to have or be) and exclusion criteria (what would disqualify you). Typical inclusion criteria cover your diagnosis, age range, and sometimes how far along your disease has progressed. Exclusion criteria often involve other medical conditions, medications you are currently taking, lab values like liver or kidney function, and how recently you received other treatments. These rules exist to protect participant safety and to make sure the study results are interpretable, but they can feel frustratingly restrictive.

The strictness of eligibility criteria varies by the phase of the trial. Earlier-phase studies, which are testing safety and dosing in smaller groups, tend to be more selective. Later-phase trials, which are comparing a treatment against a standard of care in larger groups, can be broader but still carry their own restrictions. Research on breast cancer trials confirmed that the types of exclusion criteria used were significantly tied to the trial phase and the location of the study site.⁴ A study of acute leukemia trials found that some lab-value cutoffs in later-phase trials did not always align well with the actual safety profile of the drug being tested, suggesting that certain exclusion criteria are carried forward by convention rather than by necessity.⁵

There is a growing push to loosen overly restrictive criteria. Major cancer organizations have recommended modernizing rules around washout periods, allowed medications, prior treatments, lab thresholds, and performance status to make trials more representative of the actual patient population.⁶ When researchers modeled what would happen if criteria were broadened, the number of eligible patients jumped by about 78%, with the biggest gains among older adults, women, Black patients, and people with lower incomes.⁷ If you were told you did not qualify for a trial a few years ago, it may be worth checking again, because eligibility standards in your disease area may have changed.

Your Doctor’s Role in the Search

Asking your doctor about clinical trials is one of the most effective steps you can take, yet the conversation does not always happen on its own. A large survey of physicians and nurses found that only about half screened all of their patients for available on-site trials, and most of that screening was done by manual chart review.⁸ Contracting and paperwork were cited as the single biggest barrier to opening more trials at their sites. Referrals to trials at other institutions were rare.

Specialty matters. Research on breast cancer showed that medical oncologists were more likely than surgeons or radiation oncologists to bring up clinical trials. Physicians who spent the most time in direct patient care were actually the least likely to discuss trials, probably because they were the most time-pressed. And the farther a physician’s practice was from a trial site, the less likely they were to refer patients at all.⁹ If your doctor does not mention trials, do not assume none exist. Ask directly whether any trial might be relevant to your situation, and ask whether a referral to an academic medical center could open up additional options.

Logistical burden on the physician side is a real factor. A study of early-phase trial referrals found that doctors who perceived the trial process as diverting time and resources from their practice were significantly less likely to refer patients.¹⁰ This means the referral gap is not necessarily about your doctor’s knowledge or willingness. It is often about the friction built into the system. Being proactive about your own search and bringing specific trial listings to your appointment can shift the dynamic.

Patient Navigators and Research Nurses

If you are treated at a cancer center or a large hospital system, a clinical trial navigator or research nurse may be able to help you identify and screen for relevant studies. These roles exist specifically to bridge the gap between trial availability and patient enrollment. At one program using an oncology nurse navigator to screen Black breast cancer patients, 86% of those found eligible agreed to enroll in one or more trials.¹¹ That is a striking number when you consider that national trial participation rates typically hover in the single digits for many cancer types.

A more recent effort at a large academic center used research nurses to pre-screen patients for genitourinary cancer trials. In the year after implementation, enrollment among Black patients and Asian patients trended upward, though the changes did not reach statistical significance given the small sample sizes.¹² The takeaway is that having someone actively look for matches on your behalf, rather than waiting for a match to find you, dramatically changes your odds of connecting with a trial. If your treatment center has a research department, call and ask whether they have a navigator or coordinator who can review your chart.

Digital Matching Tools

Beyond browsing ClinicalTrials.gov yourself, a growing ecosystem of digital tools attempts to automate the matching process. Some of these tools pull information from electronic health records and compare it against trial eligibility criteria using natural language processing, essentially reading your chart and the trial listing simultaneously and flagging possible matches.¹³ One system called CriteriaMapper, tested across multiple institutions, achieved a high level of agreement with manual expert matching when normalizing eligibility criteria across diseases like lung cancer, breast cancer, and Crohn’s disease.¹⁴

On the clinician side, a study that had 25 clinicians and research staff match synthetic patient cases to trials found that using a clinical decision support tool required significantly less mental effort than using publicly available online databases. Participants also reported feeling they had more sufficient time, though the actual minutes saved did not reach statistical significance.¹⁵ These tools are still maturing, and most are deployed within hospital systems rather than being directly available to patients. But patient-facing platforms do exist. If you search for trial-matching services online, look for ones affiliated with major medical institutions or well-known advocacy organizations. Be wary of any service that asks for payment or appears to promote a specific drug company’s product.

Decentralized Trials and Remote Participation

One of the biggest practical barriers to joining a trial has always been geography. If the nearest participating site is hours away, the time and cost of repeated visits can make enrollment impossible regardless of your medical eligibility. Decentralized trials aim to solve this by using remote technologies like telemedicine visits, home nursing visits, local lab draws, and direct-to-patient medication shipments.

Survey research on cancer patients and survivors found that people were significantly more willing to consent to a trial when remote tools reduced the need to travel to the study site.¹⁶ Not every trial offers decentralized options, but the trend has accelerated since 2020, and it is worth asking the study coordinator whether any remote components are available when you contact a trial site. Even partially decentralized designs, where some visits happen at the clinic and others happen remotely, can cut your travel burden substantially.

Insurance, Costs, and Financial Support

A common worry is that your insurance will not cover anything related to a clinical trial. The reality is more favorable than most people expect. Under the Affordable Care Act, most private health insurers are required to cover routine patient care costs for individuals participating in clinical trials.¹⁷ “Routine costs” means the standard care you would receive even if you were not on the trial: doctor visits, lab work, imaging. The experimental drug or device itself is usually provided at no cost by the trial sponsor. What you typically pay out of pocket is the same copays and deductibles you would owe for regular treatment.

That said, the mandate does not cover everything. Travel, lodging, time off work, and childcare are all costs that fall on you, and they add up quickly for trials that require frequent site visits. Some research institutions and nonprofits have started financial reimbursement programs to help offset these non-clinical expenses. One such program, endorsed by the FDA and state legislatures in Texas and Pennsylvania, provides travel and lodging reimbursement for cancer trial participants with household incomes up to 700% of the federal poverty level.¹⁸ Ask the study coordinator about financial assistance before assuming you cannot afford to participate.

Insurance denials do still happen, despite the ACA mandate. Research has documented that cancer centers sometimes encounter insurers pushing back on coverage for trial-related care, and the process of resolving those denials can delay enrollment.¹⁹ If you receive a denial, know that you have the right to appeal. The study team or your hospital’s financial counseling office can often help you navigate that process.

Understanding Informed Consent

Before you enroll in any trial, you will go through an informed consent process. This involves reading a document that describes the study’s purpose, what will happen to you during the trial, the potential risks and benefits, your alternatives, and your right to withdraw at any time. These documents have a reputation for being long and dense, and that reputation is deserved. But research has shown that when consent forms are simplified, understanding improves regardless of a person’s health literacy level.²⁰

You should feel completely free to ask the research team to explain anything you do not understand. Ask what the known side effects are, what happens if the treatment does not work, and whether you will know if you are receiving the experimental treatment or a placebo. A good research team expects these questions and will not rush you. Signing the consent form is not a binding contract. You can leave the trial at any point for any reason without it affecting your regular medical care.

Why Diversity in Trials Matters to You Personally

You may have heard that clinical trials have historically enrolled participants who do not reflect the diversity of the people who actually get the diseases being studied. This is not just a fairness issue. It is a practical one. If a drug was tested overwhelmingly in one demographic group, the evidence for how it works in your body, with your genetics, your coexisting conditions, and your medication profile, may be thinner than you would like.

The barriers behind this underrepresentation are structural. Financial strain, limited paid leave, inadequate insurance, the concentration of trial sites in large academic centers, and transportation and childcare burdens all disproportionately affect racial and ethnic minority patients and people with lower incomes.²¹ Historical and ongoing mistrust of the medical research system compounds these access problems. The FDA has issued draft guidance urging sponsors to develop diversity action plans, but gaps in existing data, including poor-quality measures of race, ethnicity, and socioeconomic status, make it difficult to assess how much progress is actually being made.²²

Biomarker-Driven and Precision Medicine Trials

If you have undergone genetic or molecular testing for your condition, particularly in cancer, you may be eligible for a category of trials organized around specific biological markers rather than around your cancer’s location in the body. These come in two main flavors. Basket trials test a single targeted therapy across multiple cancer types that share a common molecular alteration. Umbrella trials test multiple therapies for a single cancer type, assigning patients to treatment arms based on their individual molecular profile.²³

A review of basket studies in oncology identified 25 that restricted enrollment to participants with a specific genetic biomarker and reported efficacy results.²⁴ If your doctor has told you that your tumor carries a particular mutation, ask specifically whether any basket or umbrella trials target it. These trials can offer access to drugs that would not be available through standard treatment pathways for your cancer type, because the drug might only be approved for a different cancer that happens to share the same molecular feature.

Expanded Access and Right to Try

If you do not qualify for any open trial, or if no trial exists for your condition, two other pathways can sometimes provide access to experimental treatments. The FDA’s Expanded Access program, also called compassionate use, allows patients with serious or life-threatening conditions to use unapproved drugs outside of a clinical trial when no comparable alternative exists.²⁵ Your physician submits a request to the FDA and to the drug’s manufacturer, and the FDA approves the vast majority of these requests, often within days.

A second pathway, created by federal legislation in 2018, is called Right to Try. It allows patients who have exhausted approved treatment options to request investigational drugs directly from the manufacturer without going through the FDA.²⁶ The key difference is regulatory oversight: Expanded Access involves FDA review, while Right to Try bypasses it. In practice, most requests still go through the Expanded Access route because manufacturers prefer the established process and the safety monitoring it includes. Either way, these are options of last resort, and your physician needs to initiate the process on your behalf.

What Happens After a Trial Ends

A question people rarely think about before enrolling is what happens when the study period is over, especially if the experimental treatment was working for them. Access to the investigational drug after a trial concludes is not guaranteed, and the logistics are genuinely complicated. Global research and bioethics communities agree that continued access should be made available with clearly defined rules set in advance, but the process involves multiple parties: the drug’s sponsor, the researchers running the trial, and sometimes the government of the country where you were treated.²⁷

Before enrolling, ask the study team directly: if this treatment helps me, will I be able to continue receiving it after the trial? Some protocols include an open-label extension phase for participants who benefit. Others require you to transition to the commercial product once it is approved, which may take months or years. Still others have no formal plan for continued access at all. Knowing this up front helps you weigh the decision with full information rather than facing an unpleasant surprise when the study wraps up.