The most serious effect is death. Anywhere from 6 hours to 10 days after consumption of the toxin (average is 18-36 hours), symptoms would start to appear. Since this is a neurotoxin, the symptoms can include double vision, slurred speech, difficulty swallowing, and muscle weakness. If untreated, it can eventually lead to respiratory paralysis.
If someone does recover, the effects can be felt for a long time - maybe even years - afterwards.