When used by expectant mothers, LSD may cause birth defects or miscarriages. You can develop tolerance to LSD very quickly. This means that after taking it for several days, you can no longer feel the psychedelic effects. To feel them again, users must abstain for a few days. LSD does not appear to cause physical dependence, even after long-term use.
Regular users can become psychologically dependent.
They feel like they need the drug and it becomes the centre of their lives. Without it, they get anxious or even panicky.