Abstract
There is no study of effects specific to McKennaii. Everything that is documented applies to psilocybin mushrooms as a group: according to the Trimbos Institute, people notice changes in perception 20 to 60 minutes after taking them, and the effects last about three to four hours. How strong a given amount is depends on the mushroom more than on the cultivar name. This page summarises the acute effects and the documented risks. Psilocybin mushrooms are illegal in the Netherlands and in most other countries, and nothing here is meant to encourage their use.
Keywords onset, duration, risks, interactions
Strain-specific effects are not documented
Descriptions online attribute particular qualities to McKennaii, such as strong visuals or a calm or intense character. We found no controlled observation behind any of them. The psilocybin content of single mushrooms varies by tens of percent within one strain and up to fourfold between harvests of one culture (see strain differences). Expectation, mood and surroundings also shape an experience. Differences that users attribute to a strain name can come from any of these.
Acute effects of psilocybin mushrooms
The drug information service of the Trimbos Institute, the Dutch national institute for mental health and addiction, describes the general course (Trimbos, drugsinfo.nl1):
Table 1. Course and effects of psilocybin mushrooms as described by the Trimbos Institute.
| Aspect | Description |
|---|---|
| Onset | changes in perception after 20 to 60 minutes |
| Duration | about 3 to 4 hours |
| Perception | visual effects, such as walls that seem to move in waves |
| Sound | music and sounds can feel very intense |
| Feeling | sometimes a sense of being one with nature |
| Unwanted | a "bad trip": feeling frightened or confused, suspicious, or losing control over thoughts |
People who are susceptible can develop a psychosis after using mushrooms or truffles, according to the same source.
Combinations that are documented as risky
Lithium. Researchers at Johns Hopkins analysed online reports of people who combined a classic psychedelic with lithium. Of 62 such reports, 47% described a seizure, and 39% involved medical attention (Nayak et al., 20212). The authors conclude provisionally that this combination may carry a significant seizure risk.
Serotonergic antidepressants. In an online survey with 611 reports of mushroom use while taking an antidepressant, effects were weaker than expected in 47% of cases with SSRIs and 55% with SNRIs. The dampening appeared to last up to three months after stopping (Gukasyan et al., 20233).
Driving. In the Netherlands, driving under the influence of any substance that impairs driving is prohibited by article 8 of the Road Traffic Act4.
Help and information
- In the Netherlands, the Trimbos Institute's Drugs Infolijn answers questions on 0900-1995.
- In an emergency, call 112 in the EU or 999 in the United Kingdom and say what was taken.
The legal side is covered in legal status. How the species and the name relate is in what McKennaii is.
References
- Trimbos, drugsinfo.nl drugsinfo.nl/paddos-truffels/wat-je-moet-weten-over-paddos
- Nayak et al., 2021 pubmed.ncbi.nlm.nih.gov/34348413
- Gukasyan et al., 2023 pubmed.ncbi.nlm.nih.gov/37291890
- Road Traffic Act wetten.overheid.nl/BWBR0006622