Toxicologist: poisoning and its treatment

A toxicologist is a physician who specializes in the prevention, evaluation, treatment, and monitoring of injuries and illnesses caused by exposure to drugs, chemicals, biological, and radiological agents. They work at the intersection of emergency care, intensive care, clinical pharmacology, occupational pathology, and public health. They consult in emergency departments and intensive care units, manage toxicology programs, and participate in toxicovigillance—the systematic monitoring of poisonings and risks. [1]

Internationally, toxicology is recognized as a medical subspecialty. Certification typically follows basic training in a related specialty and subsequent toxicology residency or fellowship. Professional societies develop standards and educational programs and support poison surveillance networks and scientific registries. [2]

In everyday clinical practice, a toxicologist sees both acute intoxications and chronic effects. Typical tasks include stabilizing vital functions, identifying the toxicant, determining the need for gastrointestinal decontamination, selecting antidotes, deciding on extracorporeal detoxification, managing complications, and coordinating with the poison control center. [3]

A separate area of focus is working with poison control centers, which advise the public and medical professionals, maintain databases on mixture compositions, and provide expert support to regulators. In the European Union, designated bodies are required to accept information on the composition of hazardous mixtures, and in the United States, a single "Poison Help" line operates. [4]

Table 1. Key competencies and roles of a toxicologist

Region	What does a specialist do?	Where it is applied	Target
Urgent Care	Stabilization of breathing, circulation, and consciousness	Admissions department, intensive care unit	Reducing mortality and complications
Diagnostics	Selection of tests, interpretation of laboratory parameters	Inpatient, remote consultations	Identification of toxicant and syndrome
Therapy	Antidotes, supportive therapy, extracorporeal methods	Resuscitation, specialized departments	Interruption of the toxic cascade
Toxicovigilance	Analysis of cases, trends, interaction with centers	Public health	Prevention and preparedness for emergencies

When to contact a toxicologist

Reasons for urgent consultation include suspected ingestion of dangerous quantities of medications, surrogate alcohol, industrial solvents, poisonous plants, as well as inhalation of combustion products or chemical vapors. Danger signs include: respiratory depression, severe drowsiness or coma, seizures, arrhythmia, sudden changes in blood pressure, signs of metabolic acidosis, unusual breath odor, pupil changes, chest or abdominal pain, and sudden visual disturbances. [5]

The risk is particularly high in children, the elderly, pregnant women, people with chronic liver and kidney disease, and those taking multiple substances at the same time. Additional risks are associated with sustained-release medications, patches, and high-concentration injection solutions. [6]

When the toxicant is unknown, a syndromic approach becomes decisive: assessment of vital signs, analysis of acid-base balance, anion and osmolar gaps, lactate, glucose, carboxyhemoglobin, and methemoglobin. Those combinations that indicate toxic alcohols or carbon monoxide poisoning require immediate specific action. [7]

A toxicologist is also called in for chronic occupational exposures, suspected drug interactions, animal poisonings, and in situations involving mass casualties and chemical accidents. [8]

Table 2. "Signal" symptoms and probable groups of toxicants

Symptom complex	Probable agents	First steps
Respiratory depression, miosis	Opioids	Airway patency, oxygen, titrated naloxone
Coma, metabolic acidosis, increased osmolar gap	Methanol, ethylene glycol	Alcohol dehydrogenase antagonist, acidosis correction, dialysis as indicated
Hypoxia with normal saturation according to pulse oximeter	Carbon monoxide	One hundred percent oxygen, hyperbaric therapy review
Redness of the skin, history of blood pressure, smoke	Cyanides in a fire	Oxygen, hydroxocobalamin, sodium thiosulfate

Diagnostic minimum in the first hours

All patients with suspected significant poisoning should have their respiration and circulation monitored, along with an ECG, glucose, blood gas analysis, electrolytes, lactate, and liver and kidney function. If toxic alcohols are suspected, the anion gap and osmolar gap are calculated; if carbon monoxide is suspected, carboxyhemoglobin is measured; if methemoglobin-forming agents are suspected, methemoglobin is measured. Universal urine drug screens have limitations in detection time and specificity and should not delay therapy. [9]

If acetaminophen exposure is suspected, measuring the level at 4 hours and plotting the result on the Rumack-Matthew nomogram is critical for deciding whether to initiate acetylcysteine. Separate consensus documents clarify the definitions of "acute" and "high-risk" exposure and algorithms for initiating therapy when the time is unknown. [10]

Table 3. Basic laboratory parameters and their interpretation in cases of poisoning

Indicator	What are we looking for?	Possible interpretation
Gas composition, lactate	Metabolic acidosis	Toxic alcohols, cyanides, shock
Anion gap	Enlarged	Metabolites of ethylene glycol and methanol, lactate
Osmolar gap	Enlarged	The presence of osmotically active alcohols
Carboxyhemoglobin	Increased	Carbon monoxide poisoning
Methemoglobin	Increased	Oxidizers, nitrites, some medications

Decontamination of the gastrointestinal tract

Routine use of a single dose of activated charcoal, gastric lavage, or syrup of ipecac is not indicated. The decision to prescribe activated charcoal is made on an individual basis: maximum benefit is achieved within 1 hour; later benefit is possible with higher doses, sustained release, and delayed gastric emptying. Gastric lavage and syrup of ipecac are not routinely recommended due to questionable efficacy and the risk of complications. [11]

Total bowel irrigation with polyethylene glycol is not used routinely but may be considered for ingestion of drug packets, iron, lithium, and to remove delayed release forms of some drugs. The quality of evidence remains limited, and the decision should be made by a toxicologist. [12]

Table 4. Modern view on decontamination methods

Method	When to consider	When to Avoid	Base
Activated carbon	In the first 1-2 hours, later with large doses and delayed forms	Unprotected airways, intestinal obstruction	Position papers of associations
Gastric lavage	Rarely, only at potentially lethal doses for approximately 1 hour and with respiratory protection	Most situations	Updated expert positions
Complete bowel lavage	Drug packages, iron, lithium, delayed release forms	Hemodynamic instability, obstruction	Updated position on the method
Ipecac syrup	Not recommended	Always	Updated expert positions

Common clinical scenarios and modern approaches

Acetaminophen

The key is to determine the time and plot the 4-hour level on the nomogram. If the treatment line is at or above the target, acetylcysteine is started. The 2023 consensus document for the US and Canada clarifies the definitions of "acute" and "high-risk" administration, as well as management in cases of unknown time. [13]

A number of centers are switching from three-bag regimens to simplified two-bag regimens, which, according to systematic reviews and studies, are associated with fewer infusion reactions and errors, while maintaining comparable efficacy in preventing hepatotoxicity. Shorter regimens are also being discussed based on new data, but they require local protocols and consultation with a toxicologist. [14]

Table 5. Acetylcysteine for acetaminophen poisoning: regimens and monitoring

Scheme	Load	Support	Advantages	Control
Classic three-stage 21 hours	150 mg per kg in 1 hour	50 mg/kg over 4 hours, then 100 mg/kg over 16 hours	Widely known	Clinic, liver enzymes
Simplified two-stage 20 hours	200 mg per kg over 4 hours	100 mg/kg for 16 hours	Fewer reactions and errors	Clinical picture, enzymes, levels according to indications
Shortened protocols 12 hours	250 mg per kg in total	By local protocol	Potential convenience when selecting	Only according to protocol and with expert control

[15]

Opioids

For respiratory depression, naloxone is the key antidote. In the setting of potent synthetic opioids, titrated approaches in the clinic are preferred to restore breathing and avoid severe withdrawal. For community care, many jurisdictions maintain standard starting doses for non-physician providers. With long-term or potent opioids, repeated administration or infusion may be necessary. [16]

Flumazenil is used very selectively in benzodiazepine poisoning due to the risk of seizures, especially in patients with chronic use or mixed poisoning. Detailed current reviews and guidelines confirm the need for strict selection and priority of supportive therapy. [17]

Toxic alcohols

If methanol or ethylene glycol exposure is suspected, treatment should begin immediately, without waiting for toxicant levels to be determined, if clinical and laboratory findings suggest poisoning. The antidote of choice is fomepizole, an alcohol dehydrogenase inhibitor; hemodialysis and acidosis correction are added if necessary. An osmolar gap is helpful, but its absence does not rule out poisoning. [18]

Table 6. Toxic Alcohols: A Quick Guide

Sign	What supports the diagnosis	First steps
Anion gap is increased	Glycolic and formic acids	Bicarbonate as indicated, dialysis as per criteria
The osmolar gap is increased	Presence of mother alcohols	Start fomepizole, don't wait for the level
Neuro- or visual symptoms	Characteristic of methanol	Emergency consultation, dialysis as indicated
Calcium oxalates in urine	Supports ethylene glycol	Antidote and metabolic correction

[19]

Carbon monoxide and cyanide in fires

If carbon monoxide poisoning is suspected, high-concentration oxygen is administered immediately. Hyperbaric therapy is considered in certain situations, including pregnancy and severe neurological symptoms. The routine use of hyperbaric oxygen is controversial, and the decision is made by the team based on the indications and availability. [20]

If cyanide exposure is suspected, especially in fire victims, hydroxocobalamin is used, often in combination with sodium thiosulfate. These drugs are recognized by regulators and relevant agencies as antidotes. [21]

Table 7. Antidotes and key indications

Antidote	For what	The dosage is approximate	Comments
Naloxone	Opioids	Titrated until breathing is restored	Infusion is possible with long-term medications
Acetylcysteine	Acetaminophen	See the table of diagrams	An early start is critical
Fomepizole	Methanol, ethylene glycol	Load 15 mg/kg, then 10 mg/kg at 12-hour intervals, then increase the dose	Recalculation during dialysis
Hydroxocobalamin	Cyanides	According to standard schemes for adults and children	Possible combination with sodium thiosulfate
Methylene blue	Methemoglobinemia	By body weight	Contraindicated in G-6-PD deficiency

[22]

Supportive and specialized therapy

High-dose insulin therapy for severe calcium channel blocker or beta-blocker intoxication is used to improve myocardial contractility and perfusion. This method requires glycemic and potassium monitoring and is combined with vasopressors and other supportive measures as indicated. Guidelines clarify its place as a first-line option for signs of myocardial dysfunction. [23]

Lipid emulsion therapy is considered a life-saving method for life-threatening intoxications with lipophilic substances when standard approaches fail. Position papers emphasize the need for careful selection and monitoring of complications. [24]

Table 8. Specialized methods in toxicology

Method	Target	When to consider	Restrictions
High-dose insulin therapy	Calcium channel blockers, beta blockers	Myocardial dysfunction, shock	Requires strict monitoring
Lipid emulsion	Lipophilic toxins	Refractory cases	Risk of complications, not universal
Hemodialysis	Methanol, ethylene glycol, salicylates, lithium	High levels, severe clinical symptoms	Decision on criteria and availability
Hyperbaric oxygenation	Carbon monoxide	Severe cases, pregnancy	Availability, discussion of evidence

[25]

Poison Control Centers and Public Health

Poison control centers are reference institutions that receive information on the composition of mixtures, advise doctors and the public, and coordinate the response to chemical emergencies. Guidelines from international organizations describe the structure, operating mode, and key functions of such centers, emphasizing their role in reducing mortality and the burden of poisoning. [26]

24-hour helplines, antidote databases, and case notification schemes are available to the public and clinicians in various countries, speeding up access to expert information and standardising practice. [27]

Training, Certification, and Teamwork

Toxicologist training includes basic clinical training, followed by specialized residency or fellowship, and participation in scientific and educational programs of professional societies. In practice, toxicologists work in collaboration with resuscitation specialists, cardiologists, neurologists, neonatologists, occupational pathologists, clinical pharmacists, and poison control center experts. [28]

Continuous updating of knowledge is critical: annual congresses, surveillance registries, society positions and open resources on key antidotes and methods allow for rapid implementation of changes. [29]

Frequently Asked Questions

Should activated charcoal always be given for any suspected poisoning?
No. Routine administration is not recommended. Benefit is most likely if given within 1 hour of ingestion of the toxicant and for specific indications. The decision is made by the physician. [30]

How do you know if acetylcysteine is needed when taking acetaminophen?
Levels are measured after 4 hours and compared with the nomogram. If the treatment is successful, therapy is initiated and then followed according to a local algorithm, including modern two-step regimens. [31]

Is hyperbaric oxygen always necessary for carbon monoxide poisoning?
No. Indications depend on the severity, pregnancy, neurological symptoms, and logistics. The decision is individual. [32]

Is flumazenil safe to use for drowsiness from "pills"?
Only with strict selection. There is a risk of seizures, especially with chronic benzodiazepine use or mixed poisoning. Supportive care and airway protection are primary. [33]

How to promptly initiate treatment if toxic alcohols are suspected? 7
Immediately, if clinical and laboratory evidence suggests a high risk. Fomepizole, acidosis correction, and dialysis according to criteria, without waiting for toxicant level results. [34]