An overdose is exposure to an amount of a substance beyond what is intended, whether by accident, by a dosing error, or deliberately. Effects vary by drug and by person.
In the United States, Poison Control at 1-800-222-1222 provides free, confidential, 24-hour guidance for suspected overdose and medication mistakes. If a person has collapsed, has a seizure, cannot be woken, or is having trouble breathing, emergency services should be called immediately.