Secondary hazards are an important consideration when dealing with both self-poisoned and chemically contaminated patients. Secondary exposure of hospital staff following the admission of a poisoned patient is relatively rare but potentially serious. Risks usually arise from chemical conversion of a deliberately ingested toxic substance and subsequent offgassing, but there may be toxic substances on the victim or their clothing. Surface contamination is a more common concern in cases where patients have been exposed to chemical releases. This paper presents a narrative review that considers some of the more commonly encountered toxic chemicals and situations that may present secondary hazards in hospitals. Risks to staff can be lowered by reducing the potential for, and duration of, exposure wherever possible. Good communication with the first responders at the scene, consultation with experts, decontamination and use of personal protective equipment, together with regular training, can minimize risks in the hospital environment.