AuthorisedTherapeutic exploratory (Phase II)Interventional

Intravenous iron in the management of drug-resistant restless legs syndrome: a randomized controlled delayed-start trial. IRON-RLS

This study, called IRON-RLS, focuses on adults who experience restless legs syndrome (RLS) that hasn't responded well to usual treatments. The main goal is to see if giving a specific type of iron directly into a vein (intravenous iron) can reduce the symptoms of RLS over three months. Participants will be split into two groups: one receiving the iron treatment immediately, and the other receiving it after a delay. Researchers will compare how much the severity of RLS symptoms changes in both groups. They will also look at how much the restless leg movements during sleep improve and if sleep quality gets better. This research aims to find better ways to manage severe RLS.

At a glance

Status

Authorised

Phase

Therapeutic exploratory (Phase II)

Sponsor

Centre Hospitalier Universitaire De Montpellier

Enrolment target

Start

29 May 2026

Restless legs syndrome

What is this study about?

This study is called IRON-RLS, and it's looking into a new way to help people with restless legs syndrome (RLS). RLS can be really uncomfortable, causing an irresistible urge to move your legs, often at night, which can make it hard to sleep. For some people, usual treatments don't work very well, and this study is specifically for them.

The main idea behind this study is to see if giving a special iron treatment, called ferric carboxymaltose, directly into a vein (like getting a drip) can make a difference. Iron plays an important role in how our bodies and brains work, and sometimes low iron levels, even if not diagnosed as anaemia, can be linked to RLS. The study wants to find out if topping up iron levels in this way can help reduce the symptoms of RLS and improve sleep.

Participants in this study will be split into two groups by chance. One group will receive the iron treatment early on, and the other group will receive it after a short delay. This allows the researchers to compare the effects of the treatment. They will closely monitor your RLS symptoms, sleep patterns, and iron levels before and after the treatment to understand how well it works and if it's safe.

Key takeaways

This study is for adults with restless legs syndrome resistant to usual treatments.
It tests an iron treatment given directly into the bloodstream.
Researchers will compare immediate treatment with delayed treatment.
It aims to see if intravenous iron can reduce RLS symptoms and improve sleep.
Participation involves clinic visits, assessments, and follow-up over about 6 months.

Who may be eligible?

To be considered for this study, you need to be an adult, 18 years of age or older. There's no upper age limit, meaning older adults are welcome to participate too. This study is open to both men and women.

The main condition for joining is that you must have restless legs syndrome that hasn't settled down with regular treatments. The researchers want to specifically help people who are still struggling with their RLS symptoms despite trying other options.

There might be other specific health requirements or conditions that mean you can't join, which the study doctors will explain in more detail. This is to make sure the study is safe for everyone involved and that the results are as clear as possible.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years old or older?
Do you have restless legs syndrome?
Have your RLS symptoms not improved with other treatments?
Are you able to attend clinic visits for assessments and treatments?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you'll have several visits to the study clinic. At the first visit (V1), you'll have a number of checks, including a detailed look at your symptoms and perhaps some blood tests and a sleep study. Some participants will also have a special test where a small amount of fluid from around your spine is collected (CSF parameters) – this will be discussed with you in detail.

Then, you'll be assigned by chance to one of two groups. One group will receive the iron treatment shortly after V1. The other group will receive the treatment a bit later. The iron treatment itself is given through a drip into your arm, usually taking some time. You'll then have follow-up visits (V3, V5), typically at 3 and 6 months after your first visit. At these visits, the researchers will re-evaluate your RLS symptoms, sleep, and take more blood samples to see how you're responding. The total duration of your participation in the study would be around 6 months.

Potential risks and benefits

Taking part in any study has potential ups and downs. On the benefit side, you might find that the iron treatment significantly improves your restless legs syndrome symptoms and sleep, especially if other treatments haven't worked for you. You'll also receive careful monitoring of your health throughout the study. However, there are potential risks, such as side effects from the iron infusion (like allergic reactions, headaches, or upset stomach) or discomfort from blood tests and other procedures. Remember, you can also leave the study at any time, for any reason, without it affecting your usual medical care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
France

Common questions

What is restless legs syndrome (RLS)?

RLS is a condition where you have an overwhelming urge to move your legs, often with an uncomfortable feeling. It usually happens when you're resting, especially in the evening or night.

What does 'intravenous iron' mean?

It means the iron treatment is given directly into a vein, usually in your arm, through a drip. This allows the iron to get into your body quickly.

Why are they studying this iron treatment?

Researchers believe that for some people with RLS that isn't helped by other treatments, low iron levels in the brain might play a role. This study explores if boosting iron can help.

Will I know if I'm getting the treatment or the delayed treatment?

You might not know which group you are in immediately, as this helps make the study fair. The study team will explain how this works.

How long will the study last for me?

Your involvement in the study will typically last for about 6 months, including several visits for assessments and treatments.