AuthorisedTherapeutic confirmatory (Phase III)Interventional

A multicenter, phase 3, randomized, placebo-controlled, triple-blind crossover study of candesartan for prevention of chronic cluster headache (Chronic CandClus2)

This research study is for people who suffer from chronic cluster headaches, which are very painful headaches that happen frequently. The study aims to find out if a drug called candesartan can help prevent these attacks. Participants will be given either candesartan or a dummy pill (placebo) in a way that neither they nor their doctors know which one they are taking. This helps ensure fair results. Researchers will then check if candesartan can reduce how often severe cluster headache attacks happen and how intense they are over several weeks. The study also looks at how the treatment affects quality of life and other headache-related issues.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Helse Bergen HF, St. Olavs Hospital HF

Enrolment target

Start

04 Nov 2025

chronic cluster headache

What is this study about?

This study is about understanding if a medicine called candesartan can be an effective treatment for people who experience chronic cluster headaches. Chronic cluster headaches are a very painful and often disabling type of headache that occur regularly over long periods.

The main goal of the study is to see if candesartan can reduce how often severe cluster headache attacks happen each week. It also looks at other important things, like how much less intense the headaches become, if people need less acute pain relief, and how their overall quality of life improves. By carefully comparing candesartan to a dummy pill (placebo), researchers can be confident if any changes are due to the medicine itself.

This is a 'Phase 3' study, which means it's a critical stage of research. If the results are positive, it could mean a new treatment option for people living with chronic cluster headaches. The study is designed to be very thorough to make sure the findings are accurate and reliable.

Key takeaways

This study investigates if candesartan can prevent chronic cluster headaches.
It compares candesartan to a dummy pill (placebo) in a fair way.
The main goal is to reduce how often severe headaches happen.
Participants must be 18 or older and have chronic cluster headaches.
It's a 'Phase 3' study, which means it's a big step towards a potential new treatment.
You can stop participating at any time.

Who may be eligible?

To join this study, participants must be at least 18 years old. People of any gender can take part.

More detailed information about specific health conditions, other medications you might be taking, and your history with cluster headaches would be discussed with the study team. This ensures the study is safe for you and that the results will be clear.

It's important to have a confirmed diagnosis of chronic cluster headaches to be considered for this research.

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 a diagnosis of chronic cluster headaches?
Are you comfortable potentially taking either a new medicine or a dummy pill?
Are you able to attend study visits and keep a headache diary?

Answer every question to see your result.

What does participation involve?

If you decide to join, you would be randomly assigned to take either the study drug, candesartan, or a dummy pill (placebo). You and your doctors won't know which one you are taking, which helps make the study fair. The medication will be in the form of capsules. The study will involve several visits to the clinic for assessments and check-ups. You'll likely be asked to keep a diary of your headaches. The main part of the study involves two four-week periods where you take either the study medicine or the placebo. After these periods, there will be further follow-up. The total duration of your involvement will be explained by the study team.

Potential risks and benefits

Taking part in a study like this might offer a potential benefit if the study drug helps reduce your headache attacks when other treatments haven't worked well. You would also be contributing valuable information that could help others with cluster headaches in the future. However, there are potential risks, including side effects from the medication (whether it's the active drug or placebo) or the possibility that the treatment may not work for you. You will be closely monitored by healthcare professionals. Remember, you have the right to withdraw from the study at any time, for any reason, without affecting your regular medical care.

Locations (2)

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

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Unverified
Norway
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Unverified
Denmark

Common questions

What exactly are chronic cluster headaches?

Chronic cluster headaches are very severe headaches that happen frequently and regularly over time, rather than in short bursts (called episodic). They are known for being extremely painful.

What is candesartan?

Candesartan is a medicine that's already used for other conditions, like high blood pressure. This study is exploring if it can also help prevent chronic cluster headaches.

What is a 'placebo'?

A placebo is a 'dummy' pill that looks just like the real medicine but contains no active drug. It helps researchers compare the real drug's effects more accurately.

Will I know if I'm getting the real drug or the placebo?

No, this is a 'triple-blind' study, meaning that you, your doctor, and the researchers won't know whether you're taking candesartan or the placebo until after the main part of the study is over.

What does a 'Phase 3' study mean?

Phase 3 is an important stage where a drug is tested on a larger group of people to confirm its effectiveness and safety, particularly when compared to existing treatments or a placebo.