answered Oct 06, 2010 at 12:53AM
These drugs are dose dependant. Control of levels of the drug in home made "batches" reflect in the duration. Also the drugs don't seem to be acting under more tolerance during subsequent doses.
The emotional condition present at the time of ingestion will exacerbate "Bad Trips". Psychiatric issues will also determine the result. Dosing for many weeks months or even years without any negative sequellae, can be followed with a different and sometimes noxious effect.
stephen D. Malcolm RN