Emetic

An emetic is a substance that induces vomiting. In clinical toxicology it is used to evacuate the stomach after ingestion of certain toxins when a rapid early response is possible. Its use is now limited and not routinely recommended for many poisonings due to risks such as aspiration, injury to the esophagus or stomach, and uncertain or variable efficacy. In many cases other decontamination methods or supportive care are preferred.

Mechanism and classification: emetics act through two general pathways. Central emetics stimulate the vomiting center in the medulla oblongata, often via the chemoreceptor trigger zone or dopaminergic pathways. Local or irritant emetics cause gastric irritation that triggers reflex vomiting. Historically, two main categories are described: central emetics (such as apomorphine and, in the past, ipecac) and local irritants (various stomach irritants).

Common agents: ipecacuanha syrup was once a standard antidote for poisonings but has fallen out of favor due to inconsistent results and safety concerns. Apomorphine is a potent central emetic used primarily in veterinary medicine (not commonly for humans). Household hydrogen peroxide at 3% has been used as an emetic in the past but is now discouraged in many guidelines because of risks such as aspiration and gastric rupture. Some concentrated salt solutions can act as irritants but are not recommended for routine use.

Clinical practice: emesis is generally avoided in many poisonings, and ingestion should be managed under medical supervision. Alternatives include activated charcoal, gastric lavage in select cases, and supportive care. In veterinary medicine, specific emetic agents are chosen according to species and circumstance.