Harmala alkaloids, such as harmine, harmaline, and tetrahydroharmaline, are most com- monly found in plants such as Peganum harmala (Syrian Rue), Banisteriopsis caapi, and other species of the Banisteriopsis family. They are often used in conjunction with tryptamines, especially DMT. Most commonly, these mixes are known as Ayahuasca. In fact, traditionally, it is the B. caapi vine that is called ayahuasca and the brew does not have to contain DMT.
They function by inhibiting the metabolism of monoamine compounds (thus MAOI) such as serotonin, which incidentally also inhibits the metabolism of DMT, allowing it to become active through oral ingestion, where otherwise it would be metabolized before reaching the blood brain barrier.
They differentiate themselves from other MAOI by being reversible and selective in their inhibition, reducing certain risks related to MAOI and tyramine-containing food, for example. Hence they are more correctly referred to as RIMA - reversible inhibitors of monoamine oxidase
The effects of harmalas are slightly sedating, relaxing, and at high doses can be vi- sionary and dreamlike. They can produce nausea which is usually enhanced when taken in combination with tryptamines.
When taking harmalas or any MAOI, you should be very careful with additional substances and any medication you are taking, since MAOIs interact dangerously with several types of drugs/medications.