Got this from a website used by NHS UK (it has some medical jargon but is the best description of overdose symptoms I could find)
a few people in different ends of England (Essex and County Durham) keeled over from contaminated cocaine but its not yet clear what the adulterant was (could even have been fentanyl in those cases)
4.9 Overdose
There is considerable variation in susceptibility to atropine; recovery has occurred even after 1g, whereas deaths have been reported from doses of 100mg or less for adults and 10mg for children.
Symptoms of overdose:
In overdose, the peripheral effects become more pronounced such as dilation of pupils, continuing blurred vision, or changes in near vision, severe dryness of mouth, nose or throat, dizziness and drowsiness. Other symptoms such as rapid respiration, increased respiratory rate, difficulty in breathing, increased heartbeat, hypertension, hyperthermia, fever, muscle weakness, inhibition of micturition, nausea and vomiting may occur. A rash may appear on the face, neck or upper trunk, and there may be unusual warmth, dryness or flushing of the skin. Toxic doses also cause CNS stimulation marked by nervousness, restlessness, irritability, confusion, excitement, ataxia, incoordination, slurred speech, paranoid and psychotic reactions, hallucinations and delirium and occasionally seizures. In severe overdose, central stimulation may give way to CNS depression, coma, circulatory and respiratory failure and death.
https://www.medicines.org.uk/emc/product/3124/smpc
