Monoamine Oxidase InhibitorsWhat are MAOIs?

MAOI stands for monoamine oxidase inhibitor.  In order to understand what an MAOI is, we must first understand what monoamine oxidase (MAO) is.  MAO is an enzyme which oxidizes, thereby breaking down, certain compounds to prevent them from reaching organs such as the brain when necessary.  So, an MAOI is a compound that inhibits the activity of MAO enzymes.  An MAOI allows the amines that the MAO would normally have broken down to remain active in the body for longer.

Why is this important to the study of entheogens?  MAOIs can be used to increase and modify the effects of many entheogens, especially those containing indole and tryptamine alkaloids. An MAOI is an essential component in making tryptamine alkaloids such as DMT orally active, and is therefore necessary for the preparation of ayahuasca. Pharmaceutical MAOIs may be used to treat depression, anxiety, and other mood imbalances.  It is important to be extremely cautious when working with MAOIs for any reason, as they can be toxic when combined with other substances (Voogelbreinder 2009).

MAOI Safety

MAOIs can be dangerous in certain combinations, especially when it comes to foods high in tyramine or tyrosine, which include fermented foods, aged meats or cheese, products containing yeast, etc. If you are taking an MAOI for any reason, you may want to check out our full MAOI diet list.

Combining MAOIs with tyramine-rich foods can lead to a hypertensive crisis, in which blood pressure rises rapidly.  This can lead to brain hemorrhage and possibly death.  Death is usually only a concern with ‘irreversible’ MAOIs, which are synthetic pharmaceuticals used as anti-depressants.  However, it is still important to be careful with short-term plant based MAOIs, as eating contraindicated foods on the same day as taking a short-term MAOI can still lead to a hypertensive crisis (Voogelbreinder 2009).

Combining MAOIs with a selective serotonin re-uptake inhibitor (SSRI) such as Prozac can lead to serotonin syndrome due to an overflow of serotonin in the nervous system.  This can also occur when combining an MAOI with MDMA, DXM [dextromethorphan – found in OTC cough syrup], or large quantities of serotonin precursors such as tryptophan or 5-HTP. Symptoms of serotonin syndrome include “drowsiness, rigidity, shivering, agitation, restlessness, hyperreflexia, clumsiness, nausea, flushing, diarrhea, sweating, euphoria, mental confusion, feeling of inebriation, fever, and rarely coma and death.  If the responsible chemicals are eliminated from the diet, symptoms usually subside within 24 hours.  However, in cases including delirium, symptoms have been observed to last up to 4 days” (Voogelbreinder 2009).

Essential MAOI Safety Tips

•MAOIs should not be taken with alcohol, or cough, cold, flu or hay fever medicine.
•MAOIs can interact with other medicines, such as tricyclic antidepressants. Care must be taken when taking more than one medicine. If in doubt, discuss this with your doctor.
•Foods containing tyramine should be avoided when taking MAOIs. Some of these include: cheese, chianti wine, game, home brewed beer, paté, pickled herring, and yeast extracts (such as Oxo, Marmite, Bovril, Twiglets).  Additional information on dietary restrictions.
•If stopping pharmaceutical MAOIs, do not start taking another antidepressant for 2 weeks.
•If starting pharmaceutical MAOIs, do not start until at least five weeks after stopping fluoxetine; two weeks after stopping other MAOIs, paroxetine or sertraline; and 1 week after stopping all other tricyclics, SSRIs or related antidepressants.
•People taking pharmaceutical MAOIs should carry a warning card with them. View a printable warning card.

Pharmaceutical MAOIs

Pharmaceutically manufactured monoamine oxidase inhibitors (MAOIs) are a group of medicines that are used in the treatment of depression and anxiety. Since other antidepressants, such as the tricyclics (TCAs) and selective serotonin re-uptake inhibitors (SSRIs), have become available, MAOIs have been prescribed much less.

MAOIs do not work as well as TCAs or SSRIs in people with moderate or severe depression. However, they are effective in treating atypical depression (depression with features which are opposite to the usual symptoms of depression, such as increased sleep, increased appetite, and increased weight). They can also lift mood in some depressed people who have not responded to other antidepressants.

MAOIs have also been found to be effective in the treatment of panic attacks, various phobia disorders, bulimia, PTSD, and borderline personality disorder.  Certain targeted MAOIs are also used to treat Parkinson’s disease. Since combining MAOIs with certain foods or medicines can cause serious health issues, as discussed above, individuals taking these medicines have to follow a very strict diet.  Therefore, these forms of anti-depressant have become increasingly less popular as new medications come on to the market.

Common side effects of pharmaceutical MAOIs include dry mouth, insomnia, increased heart rate, and drowsiness. Withdrawal symptoms may occur if pharmaceutical MAOIs are stopped suddenly. Therefore, the dose should be reduced gradually over a period of about four weeks.

MAOIs and Entheogens

Plants containing alkaloids that act as MAOIs have been used extensively by shamans in mixtures and brews to make other entheogens orally active, or to enhance the effects of entheogens that are already orally active.  This is because MAOIs prevent MAO enzymes from breaking down certain alkaloids in the digestive system before they can reach the brain.

Perhaps the most famous example of an entheogen that utilizes an MAOI is ayahuasca.  Ayahuasca is not just one substance – it is a brew of any number of entheogens which are skillfully combined by a shaman to produce a particular effect.  Although a variety of entheogens may be added to ayahuasca, including Brugmansia and tobacco, the only essential components are an entheogen containing DMT and an entheogen containing an MAOI.

The most commonly known combination for preparing ayahuasca is of Chacruna (Psychotria viridis) leaves and Banisteriopsis caapi vine.  However, different combinations may be used in different parts of South America.  Chacruna leaves contain DMT, and Banisteropsis caapi contains harmaline, an alkaloid that acts as an MAOI.  Usually, if DMT is consumed orally it is broken down by MAOs in the body before it can cross the blood-brain barrier and enter the central nervous system.  However, the MAOI prevents the DMT from breaking down, allowing it to enter the CNS, where it causes consciousness-expanding effects and opens one up to visions (Hofmann et. al. 1992).

MAOIs may also be found in a number of other entheogens.  For example, you may be surprised to discover that tobacco contains an MAOI, which enhances the effects of the other alkaloids in the plant, including nicotine. This may be part of the reason why it is so difficult for habitual smokers to quit.  It may also account for some of the psychoactive qualities of smoking tobacco (Herraiz & Chaparro 2005).

Coffee also contains compounds which act as MAOIs. This means that it may enhance the qualities of other substances that are consumed along with it.  One note of interest is that caffeine seems to potentiate the reinforcing properties of nicotine, meaning that people who drink a great deal of coffee may have an even more difficult time when quitting smoking (Shoaib et. al. 1999)!

Many other plants also act as MAOIs.  One fairly famous example is syrian rue, which is used   in many modern ayahuasca analogs.  Professor Benny Shanon has suggested that Moses experienced many of his connections with God through the consumption of a combination of syrian rue and acacia, both of which grew in the lands of Canaan. It is possible to prepare a potent MAOI with a simple syrian rue extraction.

Another rather famous plant which acts as an MAOI is Passionflower.  All parts of the plant contain MAO-inhibiting B-carbolines, with the root being particularly rich in these compounds. In Brazil, the juice of the fruit is sometimes combined with the dried root of Mimosa hostilis, which contains DMT, to make a psychoactive beverage known as vinho do jurema. This beverage is said to bring fantastic and meaningful dreams and visions. However, native use of this beverage has decreased due to the destruction of indigenous cultures and the increasing popularity of ayahuasca.

If you would like more information, we have an article on MAOI dietary restrictions.  We also have more detailed information on MAOIs.




Christian, Ratsch. The Encyclopedia Of Psychoactive Plants. Park Street Press, 2005.

Herraiz, T., and C. Chaparro. “Human monoamine oxidase is inhibited by tobacco smoke: beta-carboline alkaloids act as potent and reversible inhibitors.” Biochem Biophys Res Commun 326, no. 2 (2005): 378-86.

Schultes, Richard Evans and Hofmann, Albert and Ratsch, Christian. Plants Of The Gods. Healing Arts Press, 2001.

Shoaib, M., L.S. Swanner, S. Yasar, and S.R. Goldberg. “Chronic caffeine exposure potentiates nicotine self-administration in rats.” Psychopharmacology 142, no. 4 (1999): 327-33.

Voogelbreinder, Snu. The Garden of Eden. Snu Voogelbreinder, 2009.