Redose

Redose is a term used in medicine to describe the administration of a subsequent dose of a drug after the initial dose. It is used to restore or maintain therapeutic drug levels, extend the duration of effect, or reinitiate treatment if symptoms recur or if the effect wanes. In vaccines, a redose is commonly referred to as a booster dose, given after an initial immunization to enhance or prolong immunity.

The decision to redose depends on pharmacokinetics and pharmacodynamics, including a drug’s half-life, onset, peak effect, and duration, as well as the indication, patient factors such as age and kidney or liver function, and potential drug interactions. Redosing schedules are defined in drug labeling and clinical guidelines; when not specified, clinicians individualize dosing based on response and safety. The goal is to maintain efficacy while minimizing toxicity. Overexposure can cause toxicity, whereas insufficient dosing may fail to achieve therapeutic targets. In some settings, monitoring tools such as vital signs or laboratory measurements guide timing and dose.

Examples of redosing occur in emergency and routine care. Naloxone may be redosed in opioid overdose if symptoms recur due to longer-acting substances. Antibiotics are often given in divided doses over a course. Vaccines may require booster doses years later to sustain protection. Some therapies use structured maintenance regimens that rely on regular redosing to preserve clinical effect.

Redose differs from a loading dose, which is used to rapidly reach therapeutic levels, and from a maintenance dose, which is regularly repeated to sustain effect.