Some enthusiasts

...prepared 5lb of fresh P. incarnata foliage and reported:-
 
'Within about 20 minutes, we all began to experience some profound
behavioral shifts, all of us acting in a more "primal" manner. We were also quite energized and "up", with some slight distortion of colors. This very fun state lasted about three hours or so, followed by a very deep sleep in which all involved experienced quite profound dream states.'

Excessive doses of therapeutic commercial products may also have some effect.

  Alexander & Ann Shulgin

They decribe their experiences with pure synthetic harmaline as below:-

"I took a half gram of pure synthetic harmaline after fasting for over a day. The resulting nausea was greatly attenuated after I vomited. At this dose there were intense and annoying visual disturbances, and complete collapse of motor co-ordination. I could barely stagger to the bathroom, and for safety's sake locomoted by crawling. Tracers and weird visual ripplings disturbed my sight with open eyes. With eyes closed, there was eidetic imagery. It had no symbolic significance, just bothersome disjointed sequences that lacked a relevant theme. They proceeded to transform so slowly (in comparison to the speed of my thought) that they were predictable and boring. Throughout the experience I just lay hoping it would end soon. It did not seem as though I had encountered intrapsychic material which was being expressed through somatic symptoms. Rather, I felt that I was struggling to metabolize a chemical disruption of my physiological functions. Although the session was not enjoyable, I was satisfied at having educated myself about the effect produced by a penalty dose of this compound."

Rather them than me. The biggest risk of such adventures, other than mental disturbance, is the potential MOA inhibition, but it would only be likely to occur with large amounts of concentrated extracted or synthesised alkaloids as above. MAO (monoamine oxidase) is an enzyme produced in the body which breaks down amines and renders them harmless and ineffective. All MAO inhibitors interfere with the protective enzyme and leave the body vulnerable to these amines. A common substance such as tyramine, which is usually metabolized with little or no pharmacological effect, may become dangerous in the presence of an MAO inhibitor and cause headache, stiff neck, cardiovascular difficulties, and even death. MAO inhibitors may intensify and prolong the effects of other drugs (CNS depressants, narcotic analgesics, anticholinergics, dibenzazepine antidepressants, etc.) by interfering with their metabolism. In the presence of an MAO inhibitor many substances which are ordinarily non-active because of their swift metabolism may become potent psychoactive drugs. The phenomenon may create a new series of mind alterants. However, because of the complex and precarious variables involved, it is risky and foolish for anyone to experiment with these possibilities on the non-professional level.

  Gracie and Zarkov also comment further:-

''The interaction of certain foods and drugs with the MAO inhibition brought on by beta-carbolines can be fatal!! The following substances must not be ingested within 48 hours before and after taking the brew: All amphetamines or related compounds, such as MDA, MDMA, phenylpropanolamine, ephedrine, etc. (add "smart drugs" to this category.) Any foods containing tyramine, or where enzymatic processes have been used: e.g., yoghurt, sour cream, aged cheeses, wines, especially port or Chianti, beer, fermented sausages (pepperoni), soy sauce, etc. Certain other foods, including: shellfish, bananas, liver, avocados, broad beans, chocolate, coffee and others.''

So there you have it. In essence any Passiflora commercial therapeutic preparations are relatively safe but concentrated extracts or substances such as synthetic harmaline can be very dangerous.

  Much of the above information from Gracie and Zarkov and also from unidentified authors in Usenet Groups.