The term drug overdose (or simply overdose or OD) describes the ingestion or application of a drug or other substance in quantities greater than are recommended or generally practiced. An overdose is widely considered harmful and dangerous as it can result in death.

Types

The word "overdose" implies that there is a safe dosage; therefore, the term is commonly only applied to drugs, not poison. Drug overdoses are sometimes caused intentionally to commit suicide or as self-harm, but many drug overdoses are accidental and are usually the result of either irresponsible behavior or the misreading of product labels. Drug overdose often happens as a result of the use of multiple drugs with counter indications simultaneously (for instance, heroin/certain prescription pain medications and cocaine/amphetamines/alcohol.) Usage of illicit drugs that are of unexpected purity, in large quantities, or after a period of abstinence can also induce overdose. Cocaine users that inject intravenous can overdose accidentally as the margin between an optimal flash and an overdose is small.

A common unintentional overdose in young children involves multi-vitamins containing iron. Iron is a component of the hemoglobin molecule in blood, used to transport oxygen to living cells. When taken in small amounts, iron allows the body to replenish hemoglobin, but in large amounts it causes severe pH imbalances in the body. If this overdose is not treated with chelation therapy, it can lead to death or permanent coma.

Symptoms

Symptoms of overdose occur in various forms:

• Exaggerated form of normal action (e.g., sleepiness on antiepileptics, hypoglycemia on insulin)
• Other effects due to chemical properties of the medication (e.g., metabolic acidosis in aspirin, liver failure due to paracetamol)
• Non-specific symptoms due to central nervous system irritation (e.g., confusion, vertigo, nausea, vomiting, delirium, seizures)

Diagnosis

Diagnosis of an overdosed patient is generally straightforward if the drug is known. However, it can be very difficult if the patient cannot (or refuses to) state what drug they have overdosed on. At times, certain symptoms and signs exhibited by the patient, or blood tests, can reveal the drug in question. Even without knowing the drug, most patients can be treated with general supportive measures.

In some instances, antidotes may be administered if there is sufficient indication that the patient has overdosed on a particular type of medication.

Depressants

First aid may prevent a death from overdose of depressants. The common drugs in this category include opiates (ie. heroin, morphine and methadone), alcohol, and certain prescription drugs (such as Benzodiazepines). Signs of overdose are those of a depressed central nervous system — slow, infrequent or shallow breathing, blue lips or fingernails, cold or pale skin, slow or faint pulse, snoring or gurgling noises, and the inability to be aroused from nodding off (unresponsiveness).