Found this:
Handbook of Neurotoxicology, Vol II by Edward J. Massaro, Humana Press P. 237 - 238
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"3.2.2. Interactions of Hallucinogens and Acutely Administered SSRI
Acute co-administration of SSRIs in combination with hallucinogens has also been reported. We initially published a case report of an individual who ingested fluoxetine prior to ingesting LSD and noted a potentiation of the hallucinogenic responses
108 and have had numberous individuals subsequently report that a variety of SSRIs can increase the response to both tryptamine and phenethylamine hallucinogens.
SSRIs block the serotonin transporter from recycling serotonin back into the presynaptic bouton, increasing serotonin in the synapse. Among SSRIs are Fluoxetine, paroxetine, sertraine, and fluvoxamine. The acute potentiating effect between hallucinogens and SSRIs may not be surprising given that there are a handful of case reports in the medical literature indicating that SSRIs have been self-administered acutely by individuals wiht drug-abuse histories for their reinforcing effects
(109-113). In fact, many of the respondents in our study noted that during the early phase of taking an SSRI as treatment for depression, they experienced sensations that they identified as distinctly similar to the first hour or two following hallucinogen administration. Although hallucinogen action is clearly correlated to stimulation of 5HT-2 receptors, the ability of SSRIs to induce symptoms reminiscent of hallucinogens in experienced users suggest the intriguing prospect that the serotonin transporter may play a role in hallucinogenesis."
"3.2.3. Interactions of Hallucinogens and Chronically Administered Antidepressants
Chronic administration of antidepressants have vastly different effects on the hallucinogenic response than acute administration of antidepressants, suggesting that adaptive neural changes are responsible. Although acute administration of SSRIs or MAOIs can increase the response to hallucinogens, individuals who have taken an SSRI or an MAOI for at least 3 weeks have a dramatic reduction or complete abolishment of the hallucinogenic effects from LSD
(108, 116). ....The differential effect of various antidepressant agents on the response to LSD, dependent upon duration of treatment, is pharmacologically complex...."
and it then proceeds to discussion of specific receptors, responsiveness of receptors, and serotonin levels.
Bottom line - it appears that the use of SSRIs or tricyclic antidepressants, if taken individually with the hallucinogen (LSA, psilocybin, LSD, MDMA, etc.) will boost the effect - but if used for any length of time as treatment for a condition, the same drug (other than potentially the tricyclic antidepressants, as discussed in the link provided by Lee) will inhibit the action of the hallucinogen.
Comes to the same conclusion.... best to detox off of antidepressants of any variety prior to dosing with any type of hallucinogen. Either they'll suppress the therapeutic effect or you run the risk of serotonin syndrome OR amplified hallucinogenic experience.
And given that any clusterhead is seeking the medical benefit, not the "side effect," it just seems safest to detox prior to dosing.
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The question is - if RC Seeds or Psilocybin (or LSD) are going to be used to bust a cycle, and more than one treatment is required (which is usually the case), what happens from going off the anti-depressant? It's use can't be restarted during the busting treatment or it will (most likely) interfere with the effectiveness of the treatment.
I know that many people are scared of the potential side effects of using the hallucinogens as way to bust their clusters. But I think it important to know that a study of psilocybin as a potential treatment for depression (& other mental disorders) was/is being explored at Johns Hopkins.
The Hopkins study was a randomized, placebo-controlled study, and though some experienced fear and anxiety during the experience, 79% of the participants reported "moderately or greatly increased well-being or life satisfaction compared with those given a placebo at the same test session. A majority said their mood, attitudes and behaviors had changed for the better. Structured interviews with family members, friends and co-workers generally confirmed the subjects' remarks."
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This sense of well-being lasted at least up to 14 months later: Multimedia File Viewing and Clickable Links are available for Registered Members only!! You need to

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Laurie