Overinjection

Overinjection is the administration of a drug or substance in a higher dose, larger volume, or more frequent dosing than prescribed, resulting in exposure that exceeds the intended therapeutic range. It can involve intramuscular, subcutaneous, intravenous, topical, or vaccine doses and may occur in hospital, clinic, or community settings.

Causes include dose miscalculations, unit confusion (mg vs mL), mislabeling or look-alike packaging, incorrect syringe or needle, faulty dispensing devices, and workflow factors such as rushed practice or miscommunication. Inadequate verification and risks with high-risk medications contribute to occurrences.

Consequences depend on the substance but can include systemic toxicity, organ injury, or life-threatening reactions, as well as local tissue damage at the injection site. Examples include local anesthetic overdose with CNS or cardiovascular toxicity, insulin overdose causing hypoglycemia, and excessive systemic exposure to potent drugs.

Prevention emphasizes double-checking doses, clear labeling, unit-consistent prescribing, and technology aids such as barcodes and electronic dose alerts. Standardized dosing protocols, pharmacist or nurse verification for high-risk meds, proper syringe calibration, and adequate staffing reduce risk. Education and a culture of safety are essential.

Management involves stopping the administration, monitoring vital signs, and assessing for symptoms. Follow local overdose protocols, seek toxicology input as needed, provide supportive care (airway, breathing, circulation), administer antidotes if indicated, and document the incident to support quality improvement.