There are no known physical dangers attributable to long term LSD use. In particular there is no reliable evidence that LSD causes brain damage or damage to future children. Adverse psychological effects are possible after one trip, but are more common in regular users. For some users, the experience of hallucinating can be acutely distressing with various symptoms including paranoia; phobia and ideation take time to subside.

Case studies of prolonged serious adverse psychological reactions are reported in the literature, but appear to be rare.

These reactions can be psychotic in nature and generally occur among those with existing or latent mental illness, most commonly after repeated LSD use, when LSD has perhaps acted as ‘the final straw’. Among drug users such individuals are marked out as ‘acid casualties’, those who have taken so much LSD over a period of time that they never quite come back to ‘normal’ consciousness.

A number of LSD users report a short-lived vivid reliving of a past trip without use of the drug known as a ‘flashback’. Part of LSD’s media portfolio as a horror drug were claims that users could have flashbacks lasting days or even weeks. In truth an LSD flashback (which can occur up to months after using the drug) only lasts a few minutes and is rarely dangerous although it can leave the person feeling anxious, disorientated or distressed. Flashbacks are most likely to happen in situations reminiscent of past LSD experiences or sometimes when a past user is smoking cannabis.

There is no physical dependence to LSD, but tolerance to the drug builds up rapidly. After 24 hours to achieve the same effect a much larger dose is necessary. After 3 – 4 days of increasing the dosage, a limit is reached whereby no dose would be effective. A break of around three days would be required for LSD ‘sensitivity’ to return. Small minorities of those who have ever used LSD become psychologically dependent.

Other hallucinogens

The most generally available are the hallucinogenic or ‘Magic Mushrooms’ which grow wild in many parts of Britain. The effects are similar to LSD, but milder.

The main danger is that the wrong mushroom will be picked which could be highly poisonous. Eating wild mushrooms is not illegal, but any attempt to ‘process’ the mushroom, even by drying them out, could result in a charge of being in possession of psilocin, a Class A drug under the Misuse of Drugs Act.

source; Drug Notes 2 (Institute for the Study of Drug Dependence 1996 p9)