An overdose occurs when a toxic (poisonous) amount of a drug or medicine is taken. Substances that can cause harm when too much is taken include alcohol, prescription and over-the-counter medications, illegal drugs and some herbal remedies. An overdose is a medical emergency that requires immediate medical attention. Always call triple zero (000) if a drug overdose is known or suspected. A person’s tolerance to overdose varies with age, state of health, how the substance was consumed and other factors. The body often heals (with or without treatment). However, death is a risk in some cases. This may be instant or may follow more slowly if organs are permanently damaged. Treatment for overdose may be short term or may involve ongoing treatment (for example, in the case of self-harm or attempted suicide).