Safety and drug interactions

These substances are physically very safe at the doses used for cluster headache prevention. Unlike many cluster medications, they have no known long-term organ toxicity, no addictive potential, and no withdrawal. The main risks come from interactions with other medications, from a small number of pre-existing conditions, and from psychological effects if the dose is too high. This page covers all of these in detail. Please read it carefully before your first dose.

Safety checklist

Complete every item on this list before your first dose.

• Medications listed. I have written down all medications, supplements, and herbal remedies I take.
• Interactions checked. I have checked each one against the medication table below.
• Doctor consulted (if needed). If advised for the medications I take (see table), I have talked to my doctor.
• Serotonin syndrome understood. I understand the symptoms and know when to call for help.
• Sitter arranged. I have a trusted person aware of my dose schedule, especially for my first dose.
• Triptan washout (if applicable). If I take triptans, I will wait at least five days after my last dose before starting the protocol.

Drug interactions at a glance

Psilocybin, LSD, and 5-MeO-DALT all act on the brain's serotonin system. Serotonin is a chemical your brain uses to regulate mood, sleep, and pain. Many common medications also target this system. When two or more drugs affect serotonin at the same time, their effects can combine in unwanted ways: namely, they can trigger a condition called serotonin syndrome.

Here is the quick summary:

• Lithium is a hard stop: do not combine these substances with lithium (seizure risk).
• Serotonergic medications and drugs (substances targeting the serotonin system) require a doctor conversation. The two main categories are:
  • MAOIs. Medium-high serotonin syndrome risk. They prevent your body from breaking down tryptamines, dramatically intensifying and prolonging the effects.
  • SSRIs and SNRIs. Medium-low serotonin syndrome risk. Also tend to block the protocol from working, and need a long taper before starting.
• Triptans, ergots, and many cluster preventives (verapamil, prednisone, topiramate, etc.) need to be stopped at least five days before your first dose. They block the protocol from working.
• Everything else: check with your doctor.

Check your medications

Before you start the protocol, make a list of everything you take (prescriptions, over-the-counter medications, supplements, herbal remedies) and check it against this table.

If your medication is not on this list, do not assume it is safe. Search for your medication name plus "serotonin" online, or ask your doctor or pharmacist.

How to talk to your doctor

Many doctors have limited knowledge of psychedelic-assisted treatments, and you may worry about being judged. Here is a suggested approach:

1. Frame it as harm reduction. "I have cluster headaches, and I have been reading about people using small doses of psilocybin (or LSD, or 5-MeO-DALT) to prevent attacks. I would like your help making sure it is safe with my medications."

2. Bring this page. Show them the medication table above and the serotonin syndrome section below. Doctors respond well to specific, concrete questions.

3. Ask about your specific medications. "Can you check whether any of my prescriptions interact with a serotonin receptor agonist?"

4. Know that they cannot report you. Doctor-patient conversations are confidential. Your doctor may advise against it, but they cannot report you to law enforcement for asking.

5. If your doctor refuses to engage, that is a signal to find another opinion if possible. Some neurologists, headache specialists, and psychiatrists are familiar with the patient practice and can advise on safe use.

Serotonin syndrome: what you need to know

Serotonin syndrome happens when your brain is flooded with too much serotonin. It is most likely when one of these substances is combined with another drug that also raises serotonin, especially MAOIs, or multiple serotonergic drugs stacking together. It is treatable, and knowing the signs is what makes it manageable rather than dangerous.

The risk increases with higher doses and more serotonergic drugs, but it is hard to predict in advance exactly which combination or dose will trigger it. That is why we recommend talking to your doctor, starting with low doses, and having a sitter.

Symptoms

Call emergency services immediately if any of these severe symptoms occur:

• Seizure (uncontrolled shaking, loss of consciousness).
• High fever (above 38.5°C / 101.3°F).
• Fainting.
• Severe muscle spasms or muscle rigidity (your body feels locked up).
• Uncontrollable side-to-side eye movements.
• Fast or irregular heartbeat combined with feeling very unwell.
• Any symptom (including the milder ones below) rapidly getting worse.

Call your doctor if you experience these milder symptoms:

• Rapid heartbeat, shivering, or heavy sweating persisting after 30 minutes.
• Muscle twitching or jerking.
• Nausea or diarrhea.

Serotonin syndrome symptoms range from mild (left) to severe (right). The red line marks when to call emergency services.

If you ever need emergency medical help, it is crucial that the medical team knows what you took. Tell them you took psilocybin (or LSD, or 5-MeO-DALT), and list every other medication. Serotonin syndrome is treatable, but it needs to be correctly identified.

Resources for more detail

• Demystifying Serotonin Syndrome (Canadian Family Physician) — includes a printable patient information sheet.
• Serotonin Syndrome (Cleveland Clinic).
• Serotonin Syndrome (Mayo Clinic).

Drug interactions in detail

This section explains each drug category from the table above in more depth. Read the parts that apply to you.

Lithium

Lithium is a mood stabilizer prescribed for bipolar disorder and also used as a preventative treatment for cluster headaches. The combination of lithium with psilocybin or LSD can cause seizures. The most direct evidence is a 2021 Johns Hopkins analysis of online experience reports: of 62 reports describing the combination of a classic psychedelic with lithium, 47% involved seizures, and 39% involved a visit to medical attention. By contrast, 0 of 34 reports of psychedelics combined with lamotrigine (a different mood stabilizer) involved seizures.^[2] The mechanism is not fully understood, and there is no specific data on 5-MeO-DALT, but the prudent assumption is that the same risk applies.

If you take lithium, do not start this protocol. Talk to your doctor about safely tapering off if you want to try. Lithium has a narrow therapeutic window and must be tapered slowly under medical supervision.

MAOIs

MAOIs (monoamine oxidase inhibitors) are medications that slow down the body's ability to break down serotonin and tryptamines. This creates two distinct concerns when combined with psilocybin or 5-MeO-DALT (LSD is metabolised by a different pathway and is less affected, but caution still applies):

• Serotonin syndrome. Because MAOIs prevent your body from clearing serotonin normally, serotonin can build up to dangerous levels. Symptoms may develop during or even hours after taking the dose. See the serotonin syndrome section above.
• Intensified and prolonged effects. MAOIs make orally-active tryptamines dramatically stronger and longer-lasting. A dose that would normally produce mild preventive effects can instead produce an intense psychedelic experience.

Common MAOIs include:

• Prescription antidepressants: phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), moclobemide (Manerix).
• Antibiotics: linezolid.
• Plant-based: ayahuasca brews, Syrian rue (harmal), changa blends (which often contain harmine or harmaline).

If you take an MAOI, you must talk to your doctor before starting. If your doctor gives the go-ahead, always have a sitter who knows the symptoms of serotonin syndrome, and have them stay with you for at least an hour afterward. Symptoms can be delayed when MAOIs are involved.

SSRIs and SNRIs

SSRIs and SNRIs are very commonly prescribed antidepressants. They work by increasing serotonin levels in the brain. When combined with psilocybin, LSD, or 5-MeO-DALT (which also activate serotonin receptors), there are two issues:

• Serotonin syndrome stacking. The risk of serotonin syndrome from a small preventive dose combined with a single SSRI or SNRI is generally considered low, but it is not zero, especially if you are also taking other medications that affect serotonin.
• Blocking the protocol. SSRIs and SNRIs are also among the most reliable blockers of these substances. Patients on SSRIs often find the protocol simply does not work until the SSRI has cleared their system.

Common SSRIs: citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), fluvoxamine (Luvox), paroxetine (Paxil), sertraline (Zoloft).

Common SNRIs: venlafaxine (Effexor), duloxetine (Cymbalta), desvenlafaxine (Pristiq).

Talk to your doctor before combining the protocol with any SSRI or SNRI. Have a sitter for your first few doses, and make sure they are familiar with the symptoms of serotonin syndrome.

Triptans

Triptans (sumatriptan, etc.) are commonly used to abort cluster attacks. There are two concerns:

• Blocking the protocol. This is the bigger concern for prevention. Triptans are among the most reliable blockers. Patients who continue to use triptans during the protocol typically find that it does not work.
• Serotonin syndrome. Triptans interact with the serotonin system, but current evidence suggests they are unlikely to contribute meaningfully to serotonin syndrome. Caution is still advised, especially if you take other serotonergic medications.

Recommendation: Wait at least five days after your last triptan dose before starting the protocol. Exception: frovatriptan (Frova) has a longer half-life, so wait at least seven days. Many patients find that once the protocol works, they need triptans much less often.

Other serotonergic drugs

Many common medications affect serotonin, even if that is not their primary purpose. On their own, most of these have a low interaction risk. But multiple serotonergic drugs taken together can stack up to a significant risk, even if each one alone seems safe.

Drugs in this category include:

• Tricyclic antidepressants (TCAs): clomipramine, imipramine, amitriptyline, nortriptyline.
• Opioid painkillers: tramadol, methadone, meperidine, fentanyl. Note: morphine does not have a dangerous serotonin interaction.
• Cough suppressant: dextromethorphan (DXM), found in over-the-counter cold and cough medicines.
• Herbal: St. John's Wort, a common herbal supplement for mood.
• Stimulants: amphetamine (Adderall, Vyvanse).
• Recreational drugs: MDMA / ecstasy.
• Antihistamines: chlorpheniramine, brompheniramine.

Alcohol and nicotine

Alcohol and tobacco are known triggers for cluster headache attacks during a cycle. Most patients already avoid them. Beyond that, there are two specific reasons to avoid them around dosing:

• Avoid alcohol on dosing days and the day after. It can intensify the experience unpredictably and may interfere with the protocol.
• Avoid heavy tobacco use during the dose. Some patients report nausea is worse with nicotine.

A note on opiates

The inclusion of opiates on the blockers list comes from the Clusterbusters patient community list,^[1] based on accumulated experience that they can blunt the effect of the protocol. The pharmacological basis is less well established than for the other categories above, but a small body of older animal research has shown that opioids and serotonergic psychedelics can interact at the receptor level, with opioids antagonising hallucinogen effects at low doses.^[3] Patients are advised to err on the side of stopping or reducing opiates several days before dosing, in coordination with the prescribing doctor.

Drugs that are generally considered safe

The following are not known to interact significantly with these substances:^[1]

• Antibiotics (other than linezolid, see MAOIs).
• NSAIDs (non-steroidal anti-inflammatories): aspirin, acetaminophen / paracetamol, ibuprofen, naproxen, indomethacin.
• Antacids and anti-ulcer medications.
• Asthma medications.
• Insulin.
• Caffeine and energy drinks.
• B-complex and multi-vitamins.
• Most blood pressure medications (e.g., Diovan), though discuss with your doctor if you have cardiovascular concerns.
• Statins (e.g., Lipitor).
• Anti-nausea agents (meclizine, dimenhydrinate).

This list is not exhaustive. If you take a medication not mentioned here, look it up or ask a knowledgeable physician before proceeding.

Who should NOT use these substances

Pregnancy

Do not take psilocybin, LSD, or 5-MeO-DALT if you are pregnant, trying to become pregnant, or breastfeeding. Tryptamine compounds can cause uterine contractions and may pose risks to the developing fetus.

Personal or family history of psychosis

At these low doses, these substances can rarely trigger or worsen psychotic episodes. Patients who have been diagnosed with a psychotic disorder, or whose biological parents or siblings have been, are advised not to take any of these substances. Psychotic disorders include schizophrenia, schizoaffective disorder, delusional disorder, and severe forms of some mood disorders. A large meta-analysis found the incidence of psychedelic-induced psychosis to be approximately 0.002% in population studies.^[4]

Personal or family history of bipolar disorder

Bipolar disorder is a special case. Most modern psilocybin clinical trials have excluded both people with bipolar disorder and people with first-degree relatives (parents, siblings, children) who have it. The concern is that psychedelics may rarely trigger a manic or psychotic episode in someone with a genetic predisposition. A 2024 review of the available evidence concluded that the risk varies depending on factors like which type of bipolar runs in the family, how close the relative is, and the patient's own age, and proposed a more nuanced approach than blanket exclusion.^[5] The honest summary is: the risk is real but probably small for most people in this category, and is hard to quantify precisely.

If bipolar disorder runs in your immediate family, please discuss this with a psychiatrist before considering the protocol. If you yourself have bipolar disorder, the risk is meaningfully higher and we recommend not using these substances.

Heart conditions, high blood pressure, or stroke history

Tryptamines and lysergamides cause a small, temporary increase in heart rate and blood pressure during the dose, similar to mild exercise. For most people this is harmless. If you have a serious heart condition, uncontrolled high blood pressure, a history of stroke, or significant circulation problems, talk to your doctor before proceeding.

Liver disease

Psilocybin, LSD, and 5-MeO-DALT are processed by the liver. If you have significant liver disease, talk to your doctor first.

Set and setting

"Set and setting" is the term used to describe your mental state ("set") and physical environment ("setting") at the time of the dose. Both can shape how the experience goes. Even at the small preventive doses used here, where psychoactive effects are usually mild, set and setting matter.

• Avoid dosing during an emotional crisis. Taking these substances during or right after a major emotional event (a relationship breakup, a death, a serious argument) can amplify those feelings in ways that are unhelpful. If something heavy is happening in your life, postpone the dose by a few days if you can.
• Choose a calm, familiar place. Your home is usually best. Soft lighting, a comfortable chair or couch, water, music, and a snack within reach.
• Have a sober, trusted person aware of your dose schedule. Especially for your first time, someone you trust should know what you are doing and be reachable.
• Do not drive, operate machinery, or make important decisions during the dose. This applies for the duration of the effects, which can be 8 hours or more for LSD.

Common side effects

At the small doses used for prevention, side effects are usually mild and last only as long as the dose is active.

Psilocybin and LSD

• Mild nausea in the first hour.
• Slight body warmth or "buzz".
• Mood lift or giggles.
• Mild sound or light sensitivity.
• Subtle visual or sensory changes.
• Slightly elevated heart rate.
• Increased emotionality.

5-MeO-DALT

• Reduced body temperature, cold fingers and toes (the most common side effect, in 41% of survey respondents).^[6]
• Mild dizziness or nausea (22%).
• Marked drowsiness and intense relaxation.
• 33% of survey respondents reported no side effects at all.

Side effects from a higher dose (e.g., 25 mg or more of DALT, or more than 1 g of mushrooms) tend to be stronger versions of the same. Stay at the low doses described in the protocol unless you have a specific reason to increase.

When to stop and seek medical attention

Seek medical attention if you experience any of the following:

• Chest pain, severe shortness of breath, or signs of stroke (slurred speech, sudden weakness on one side).
• A seizure.
• Severe confusion that does not resolve as the dose wears off.
• A clear break with reality (hearing voices, profound delusion) lasting beyond the duration of the dose.
• Symptoms of serotonin syndrome that are severe or worsening.
• Suicidal thoughts that feel out of your control.

Cluster headache is itself associated with a high rate of suicidal ideation, sometimes called "suicide headache" for that reason. If you are having such thoughts at any time, whether during the protocol or not, please reach out to a crisis line, a trusted person, or your doctor.