Cluster Headaches: Advocating for Access to Effective Treatments

Photo “Hell” by VasenkaPhotography used under CC BY 2.0 license

OPIS is a leading international advocate for patients with excruciating cluster headaches and similar conditions, such as SUNCT, to have legal access to certain psychedelics for medical use. This page contains information about cluster headaches, standard medical treatments, treatment with psychedelics and the evidence for their effectiveness, and additional references and resources, including for patients.


A 2-minute animated video about cluster headaches:

OPIS policy paper on legalising access to psilocybin:

Page contents

About cluster headaches

Cluster headaches, sometimes referred to as Horton’s syndrome and informally as suicide headaches, are a form of trigeminal autonomic cephalalgia and have been recognised as one of the most excruciating pains known to medicine. Unilateral and centred on one eye, the agony they cause is often compared to having a red hot ice pick driven though the eye into the brain, and sufferers are known to commit suicide to escape the pain. The colloquial term “headache” strongly misrepresents the extreme severity of the condition.

Attacks typically last one hour, with a usual range from 15 minutes to 3 hours, and they can repeat from once every second day to several times a day, even as often as 8-10 times in a day. Patients are often woken up several times during the night by attacks, and they go to extremes, including banging their head against the wall and punching their head, to try to distract themselves from the severe pain. About 85% of patients have episodic clusters lasting 1-3 months, occurring once or twice a year, usually at the same time of year, during which they have daily recurrences at the frequency mentioned; the other 15% have chronic clusters that can last for years, often with multiple attacks every single day, with little to no interruption. Cluster headaches affect about 0.1% of the total population at some point in their lives, though one review puts the figure at 0.2-0.3%, meaning that approximately 8-20 million people globally will suffer from cluster headaches.

Current medical options

Current medical treatments to prevent and abort cluster headaches include prescription drugs, high-flow oxygen and electrical stimulation of the vagus nerve, and they can all bring relief. However, no treatment is universally effective. For example:

  • Verapamil, used to prevent attacks, is only moderately effective, and it can have cardiovascular side effects.
  • Prednisone can be very effective in preventing attacks, even more so than Verapamil, but because of the serious side effects of taking oral steroids, it is usually only prescribed for about two weeks at a time, and attacks typically recur once it is stopped.
  • Sumatriptan is one of the most rapid-acting and effective means to abort attacks when injected subcutaneously, but as it can also have cardiovascular side effects, there are limits to how frequently it can be used (typically just twice a day), and therefore not every attack can be safely treated. Furthermore, it is widely reported among patients that frequent use can cause “rebound” attacks to occur.
  • High-flow oxygen delivered through a non-rebreather mask can be highly effective and is safe, though it can take 15 minutes until it works, not all patients respond, and having an oxygen delivery device constantly available presents logistical constraints.
  • A recently approved antibody-based drug, Emgality, offers a new means to significantly reduce the frequency of attacks in many patients, though it does not abort them.


Some of these treatments are costly and may therefore not be available to all patients, especially if not covered by health insurance. In addition to the limits to current therapies, cluster headaches are typically misdiagnosed, and it can be several years before a patient is correctly diagnosed and prescribed appropriate treatment.

Treatment with psychedelics and the strong evidence for effectiveness

It has been widely observed and documented that several chemicals belonging to the indoleamine family can be dramatically effective in treating cluster headaches, either by aborting individual attacks or by aborting and preventing entire cluster episodes. These chemicals include psilocybin, the psychoactive component of “magic mushrooms”, which is how it is usually consumed; LSD; and DMT (N,N-dimethyltryptamine), which is the main psychoactive component of ayahuasca, and which can also be consumed directly through inhalation. The evidence for effectiveness comes from a large number of anecdotes from users, desperate to find effective treatments; more systematic studies of online fora, surveys and interviews; and a few small-scale clinical trials (see reference section below). One study found that both psilocybin and LSD provided >70% of those who tried them with at least moderate protection from attacks, and complete preventative efficacy in 40% of cases – greater than that reported for any other conventional medication. Several participants reported that a single dose of psilocybin or LSD prevented attacks, shortened/aborted a cluster period, or induced remission from chronic cluster headache. According to other reports (ref 1, ref 2), inhaled DMT can abort an attack in as little as 3-5 seconds.

There have been a few clinical studies on psilocybin (ref 1, ref 2) and LSD (ref) to treat cluster headaches. The results from one of the trials on psilocybin were published in late 2022, and although the number of participants was too small to draw statistically significant conclusions, overall there was a ca. 30% drop in the number of attacks during the three weeks following the start of treatment, which consisted of three low doses of psilocybin at 5-day intervals. Some patients showed a much greater response than others (abstract, full scientific article and an article discussing the results). Since then, in a blinded extension phase of that trial, a 3-dose pulse of psilocybin after 6 months significantly reduced cluster attack frequency by 50% (abstract and full article). Another small, open-label study has also found a significant effect of psilocybin on attack frequency.


Aside from their effectiveness, these drugs  might be safer to use than existing treatments, because of their inherent properties and because they do not need to be used as often. Indeed, a recent Phase I clinical trial on psilocybin found no adverse effects. These drugs also offer the potential to markedly reduce the cost of treatment.

Interestingly, the hallucinogenic properties of these drugs seem not to be required for their therapeutic effect. Sub-hallucinogenic doses of psilocybin and LSD have been found to be effective for aborting and preventing cluster headaches in some patients, although others required larger doses. Furthermore, a non-hallucinogenic analogue of LSD, 2-bromo-LSD (BOL-148), appeared to have similar efficacy to LSD in a small-scale clinical trial. (As it is patent-protected and expensive to manufacture, it appears to be currently unavailable for use.) With DMT there is anecdotal evidence that sub-hallucinogenic doses (e.g. 3 mg) can abort attacks in some people, while in others, “breakthrough” doses of 20-30 mg may be needed.

Another related chemical with highly promising evidence for effectiveness in aborting and preventing attacks, that is only mildly hallucinogenic, and that can be legally purchased “for research purposes” in some jurisdictions, is 5-MeO-DALT. (Note that this is not the same chemical as 5-MeO-DMT, which is powerfully hallucinogenic.) There is also evidence that LSA (lysergic acid amide), which is contained in certain commercially available seeds, can be effective. (Reports of short-term side effects suggest it should be used with caution.)

In addition to their usefulness for cluster headaches, there is evidence that some of the drugs mentioned here, such as psilocybin, can also be effective in treating migraines, which of course are also highly debilitating. A small clinical trial has already yielded evidence for efficacy in reducing migraine frequency.

There are additional treatments that many patients find to be effective. In particular:

  • Taurine-containing energy drinks like Red Bull are reported to bring relief if cold and drunk quickly when an attack starts.
  • A specific high-dosage vitamin D3 regimen has been found to be highly effective in preventing attacks – details can be found here. (Note that vegan sources of vitamin D3 and fish-free omega-3s can be used.) (A clinical trial to test this hypothesis was started, but terminated due to the difficulty of recruiting enough patients.)
  • There is evidence that ketamine infusions, performed in a clinical setting, can lead to prolonged periods without attacks. Some of this research has been performed by Dr. Livia Granata in Zurich, with whom we are collaborating.

See the References and resources section below for more detailed information.

The ethical imperative to remove legal obstacles to access

The severe legal restrictions on the possession and use of most of these drugs complicate research and development and limit their availability to cluster headache patients. Even 5-MeO-DALT, which is only mildly hallucinogenic, has been subjected to similar restrictions in some jurisdictions. Unsurprisingly, most health services make no mention of the potential of these drugs, despite their effectiveness compared to approved treatments. Increasing numbers of clinical trials on psilocybin, LSD and MDMA for the relief of post-traumatic stress disorder (PTSD) and depression, and the trend towards decriminalisation/legalisation of marijuana, are de-stigmatising the use of mind-altering substances. Psilocybin has already been decriminalised in some locations in the US. But such stigmas remain, and are probably a significant reason why more politicians and neurologists are not yet prepared to take a strong stance to facilitate their therapeutic use.

It is nonetheless an ethical imperative that patients in severe or extreme pain be able to access and try the most effective treatments available. When governments restrict such access, compel patients to break the law and risk arrest and criminal prosecution, or impede the development of such treatments out of excessive caution, their policies are not aligned with their ethical responsibilities. Of course, as is the case with access to opioids, a balanced approach is necessary to prevent abuse, and care must be taken to ensure that a drug does not actually cause more harm than it relieves. However, the chemicals in question are relatively safe, and in the case of cluster headaches, there is currently no such balance: the restrictions in place allow extreme suffering to persist that could be prevented.

OPIS advocates that people suffering from cluster headaches should be able to access the most effective treatments known, including chemicals with psychedelic properties.

OPIS strategy, advocacy tools and campaigns

Our approach and goals include:

  • Provide useful information about cluster headaches, including evidence for effective treatments, especially psychedelics. This information is useful for patients worldwide, but also for physicians, especially neurologists, for reducing the time to diagnosis and raising awareness of effective treatment options.
  • Advocate for changes in legislation and regulations at the country level to reduce the barriers to access to psychedelics. These can include:
    • Introducing/facilitating compassionate use provisions (as in Switzerland), allowing doctors to prescribe these substances
      • The provisions should be widely available and not just to a small subset of doctors
      • Patients should be able to use psychedelics at home: this is important for their autonomy, and especially for aborting attacks
    • Formally approving these substances – including pure chemicals, whole mushrooms and extracts – for cluster headaches, potentially on a provisional basis until all the requirements for permanent approval are met
    • Decriminalising/legalising use by diagnosed cluster headache patients, to ensure they don’t fear or risk fines or prosecution for treating their pain
    • Decriminalising/legalising all personal use, including for recreational purposes – a broader, progressive approach to drug policy that also treats drug dependence as a health issue, not a criminal justice one
    • Ensuring that, when these substances can be prescribed, they are covered by health insurance

OPIS publications and videos:


We have been communicating our policy paper and video to politicians, advocacy groups, neurological associations and experts, with the goal of improving medical access to psilocybin and related substances, and ensuring that cluster headache patients can legally acquire and use these substances for therapeutic purposes.

OPIS has been collaborating with several cluster headache patient organisations and groups, including Clusterbusters, Cluster Headache Community and Finnish Horton Association. We are a member of the International Drug Policy Consortium (IDPC) and also have ongoing or past collaborations with the UK-based nonpartisan advocacy organisation Conservative Drug Policy Reform Group (CDPRG; now Centre for Evidence Based Drug Policy), International Doctors for Healthier Drug Policies (IDHDP), the Swiss-based ALPS Foundation, the non-profit TheraPsil, with whom we partnered to facilitate medical access to psilocybin for cluster headache patients in Canada, and the Qualia Research Institute. Our partnership with TheraPsil culminated in Health Canada granting a cluster headache patient legal access to psilocybin through the Special Access Program (SAP) on 7 June 2024 – read our press release. Canada and Switzerland are now the few countries where cluster headache patients have been explicitly authorised to use psychedelics outside of clinical trials.

References and resources

General information about cluster headaches

Support and advocacy organisations and communities

  • Clusterbusters, a US-based patient advocacy and support group, with a strong UK-based branch, that provides resources, including pages on various treatment options, general information on treating and preventing cluster headaches with psychedelics like psilocybin and LSD, and more detailed information on how to “bust” and prevent cycles with psychedelics using the dosing method
  • Cluster Headache Community, a friendly and supportive Facebook group that also provides a collection of files with information on various treatment options
  • Cluster headaches (trigeminal autonomic cephalalgia), another helpful Facebook group
  • r/clusterheads, a reddit community for cluster headache sufferers
  • OUCH – Organisation for the Understanding of Cluster Headache, a helpful UK-based support group (however, it does not openly advocate for the development of the drugs mentioned here)

Academic papers, studies, posts, talks, posters and interviews about the use of psychedelics to treat cluster headaches

Media articles about the use of psychedelics to treat cluster headaches

Additional resources

  • Erowid, a website providing detailed information on psychoactive substances
  • 5-MeO-DALT:
    • Legal status (partial list); see also Wikipedia page
    • Purchase: 5-MeO-DALT can be legally purchased in many countries, and it is commercially available, such as from this company that ships to many European countries, though they officially state that it is only sold as a research chemical and not for human consumption.
    • Testimonial to OPIS from a chronic cluster headache patient who has used 5-MeO-DALT: “This is the least amount of pain I’ve been in for a year and the most I’ve felt myself for the same amount of time. Usually I’m either having attacks or in a chronic shadow state of pain, so it’s been amazing.” Also: “It’s so nice to factor in the “bust” [= using psychedelics to get rid of cluster headaches] without having to lose a full evening because of the medicine’s effects [= the psychedelic effects of using psilocybin; 5-MeO-DALT has a much weaker psychedelic effect].”
  • How to Find Psychedelic Mushrooms, an article on the website of The Third Wave that provides some guidance to obtaining psilocybin mushrooms such as Psilocybe cubensis in jurisdictions where they have been decriminalised.


    Important note and disclaimer: The information supplied on this page does not constitute official medical advice. We strongly encourage anyone contemplating use of any potential therapies mentioned here to make informed decisions and to educate themselves, including about the possible experiences that may be had and about any risks associated with the legal status in their jurisdiction. Inhaling a strong dose of DMT in particular can lead to powerful experiences that could be traumatic to the uninitiated. It is especially important to be accompanied by someone trusted, and not to wait until the onset of a cluster headache for any trials.


Last updated 22 September 2025