An overview of the frequently asked questions

Frequently asked questions

We can imagine you have questions! On this page you can read the answers to the most frequently asked questions.

Frequently asked questions about participating


You can participate in a trial a maximum of four times a year. There must be at least 30 days between two trials. Some trials have a longer waiting period.

You can take part if you:

  • are 18 years or older
  • have valid identification
  • are registered with a general practitioner
  • have health insurance
  • are healthy
  • have not recently used medicines or addictive substances
  • last participated in a clinical trial no less than 30 days ago

If you don't have a Dutch passport or Dutch identification, you need a passport that has been issued by one of the countries belonging to the European Economic Area (EEA). You can also participate with a valid residency permit issued by the Netherlands and a permit to work in the EEA. Before your medical screening, ICON will make a copy of these documents. 

During the trial, you may suffer from mild symptoms like headache or nausea. That may be caused by the medication. It might also be caused by needing to fast for the trial, for example. Those side effects are no fun, but fortunately are not dangerous.

Before a medication is tested on people, it has already been studied extensively in a lab. This enables us to predict well which side effects you might get and we can prepare you for them. It almost never happens that participants suffer from unexpected side effects. For example, an allergic reaction to the medication occurs on average once a year.

Our doctors, investigators and nurses will keep a close eye on you. If they notice something about your health, they will raise the alarm right away. Additionally, every room has an emergency button and as a participant you are given a personal alarm. If you are not feeling well, then the trial stops right away.

A trial usually involves 5 to 12 participants. The groups are set up so they best match the requirements of the trial. These requirements are described for each trial. View all current trials

We take blood every day of the trial. You will be fitted with a cannula: an infusion needle that can remain in your vein for an extended time. This means we can take blood but you don't need to keep having a needle inserted every time. Read more about the trial at the research center

Your participation in a clinical trial is always voluntary. You can therefore decide to stop at any time. Sometimes you have to stop. For example because of family circumstances or if the doctor decides it is better for your health. If you stop, we will look at what portion of the compensation you are entitled to. It's only fair!

That is legally required. By signing the form, you indicate that you have given careful consideration to your participation in the trial, that you fully understand all the information and that you are voluntarily participating in the trial.

When we test a medication on healthy people, we are only studying how the medicine works in the body and whether there are any side effects. A test on patients will follow. In that trial, we look at whether the medicine works for a certain illness or condition.

Frequently asked questions about the stay


On the first day of the trial, you are expected in the late morning or early afternoon. On the last day of your stay, you leave in the late morning. Arrival and departure times may differ per trial.

If you are participating in a trial for which you have to stay at the research center for longer than ten days, it is sometimes possible to have visitors (in consultation).

No, you cannot. While you are staying at our research center, we provide all your food and drinks. There are meals and snacks in the dining room at set times. You cannot eat or drink anything else in addition to this. Certain ingredients can influence the trial. That is why we want to make sure that you don't ingest those ingredients during the trial. Read more about food and drinks during the study here

When you participate in a clinical trial, you have to do something for the trial a few times a day, such as a test or health check. But you also have a lot of time to yourself. You'll find everything you need to fill your time at the research center. For example, there are computers, Playstations, TVs with Netflix, as well as a ping pong table, pool table and a dart board. And of course there is WiFi so you can bring your own laptop or tablet. Some participants do work or study. But of course you can also just relax for a few days.

Frequently asked questions about the compensation


The amount of money you receive for your participation in a clinical trial is determined by the duration of the trial. The longer the trial takes, the higher the compensation. But there are also other factors that determine the amount of the compensation awarded, such as special medical procedures.

Yes, the tax authorities regard the compensation as "income from work." Read more about tax on the compensation here


We pay the compensation for your participation, including travel expenses, within 30 days of the follow-up screening of the trial. If you have questions about the payment, please contact us.

No, the compensation pertains to income from labor and must be deposited into the participant's own IBAN number.

Frequently asked questions about the medical screening

Medical screening

You will usually hear the result of your medical screening after two to three working days. We will call you as soon as the result is known. If you haven't heard from us after three days, please contact us.

The medical screening takes place at our medical screening center in Groningen or Utrecht. When making the appointment, you can indicate which location you prefer. The appointment confirmation states which location you are expected at. Please note: for some trials it is not possible to have the medical screening in Utrecht.

No, that is not possible. If you would like to stay over the night before or after the medical screening in Groningen or Utrecht, we recommend that you reserve a room at one of the hotels or B&Bs near the screening center.

We always invite more candidates for medical screening and start of the research study than we will ultimately need. We do that because sometimes candidates decide not to participate at the last minute. Or because candidates are rejected after all.

It can happen that we cancel the appointment for your medical screening. We will then check whether you can participate in an identical or similar trial in the near future.

You can also be assigned to the reserve group at the start of the trial. If you are a reserve and ultimately don't participate in the trial, then you can get a priority spot for a new trial. You won't be assigned to the reserve group again.

Frequently asked questions about trials with radioactive-labeled medication

Trials with radioactive-labeled medication

We are not studying whether there are side effects. Therefore it is not necessary to administer a high dose, reducing the chance of side effects.

During a clinical trial with radioactive-labeled medication, you are exposed to less than 1 mSv. That is less than the radiation you encounter in daily life. Because we want to make sure that we safely perform 14C trials, the study doctor who conducts these trials is also a radiation expert.

During a clinical trial with radioactive-labeled medication, you are exposed to less than 1 mSv. That is less than the radiation you encounter in daily life. Because we want to make sure that we safely perform 14C trials, the study doctor who conducts these trials is also a radiation expert.

Clinical trials with drugs that are radioactively labeled is mandatory before a new medicine can be registered, and is therefore generally accepted. Radioactively labeling or marking a drug is done to be able to study how quickly and to what extent the drug to be studied is absorbed, converted and excreted in the body. 

Yes. Before the drug is examined with radioactivity, it has already been extensively tested on humans in an earlier phase.

During a clinical trial with radioactive-labeled medication, you are exposed to less than 1 mSv. That is less than the radiation you encounter in daily life. Because we want to make sure that we safely perform 14C trials, the study doctor who conducts these trials is also a radiation expert.

Other questions

Yes. You can download an information booklet for study subjects who participate in medical research on the website of the Dutch government here.

ICON is continuously working on improving the experience of volunteers who stay in our research centers and participate in research. Do you have a compliment, complaint or comment? Then please let us know via the live chat on this website or by phone. See our contact form.

Without research no new medicines

New research would not be possible without participants like you. And that would mean there would be no new medicines for patients.