Rehaler and the EIC Accelerator: A Migraine Device That Failed

Rehaler, a Danish company with its registered address in Aarhus, developed a small partial-rebreathing device that raises the carbon dioxide level in the air a patient breathes while keeping oxygen normal, intended to stop attacks of migraine with aura without drugs. It was selected in the EIC Accelerator's March 2023 cut-off and was awarded an EU grant of €1.48 million for PAREMA, "PArtial REbreathing for Migraine with Aura", a €2.12 million project scheduled from November 2023 to October 2025, according to CORDIS. Its central aim was "a successful, gold-standard clinical validation of the Rehaler treatment".

That validation failed. The final report states that the randomised trial reached its interim analysis with 142 patients enrolled, and that "the interim analysis unfortunately showed that the study device was not superior to placebo". The trial was stopped and "the EIC project was terminated early", according to the CORDIS reporting page, where the project is listed as terminated. The published results conclude that partial rebreathing "was not effective" and that the device "will not be put on the market", according to the journal Headache.

Where Rehaler Stands Now

The company has not published accounts for 2025, and its website did not load when checked in September 2026. Its last filing, for 2024, showed a loss of DKK 7.6 million, cash of DKK 13.3 million and equity of DKK 15.9 million, with four employees, according to the Danish Business Authority. The final report names stroke and epilepsy as other possible uses, since the device proved safe, but no such programme has been announced.

The Technology: Breathing Back Carbon Dioxide

Earlier studies had pointed to CO2-enriched gas as a possible way to abort migraine with aura if used early in the aura, the published paper says. Rehaler's device induced moderate, steady hypercapnia while keeping oxygen levels normal, and patients were told to use it from the start of the aura. A pilot study had shown pain relief "as high or higher than current acute treatments", the company's report said before the pivotal trial.

What the EIC Award Promised, and What the Record Shows

The award promised gold-standard clinical validation. The double-blind, sham-controlled trial was stopped when an interim analysis showed no benefit: 60.0% of attacks treated with the active device were free of moderate or severe pain at two hours, against 69.7% with the sham. The device was safe, but it did not work.

1. Randomised trialRunStopped at interim.
2. EfficacyFailedNo better than sham.
3. SafetyShownNo serious adverse events.
4. Market launchAbandonedWill not be marketed.

The Money

Rehaler lost DKK 20.7 million from 2021 to 2024 while its cash peaked at DKK 26.4 million in 2023. How much of the €1.48 million grant was paid before termination is not public. The company published its negative results in a peer-reviewed journal.

What Cannot Be Checked

Why Europe Should Care

The EIC funds high-risk ideas, and some will fail. Rehaler's is a clean failure: a well-designed, sham-controlled trial answered the question, the project was stopped and the result was published. That is how public money for risky medical research should end when the answer is no.

The Verdict

Rehaler and the EIC have not been asked for comment for this article. It is based entirely on public records and published statements, linked throughout.