Introduction
Not all poisonings follow a predictable course. Some present dramatically and demand immediate intervention. Others, however, begin quietly—only to worsen over time. Paraquat poisoning is a classic example of the latter.
What appears initially as mild gastrointestinal irritation can later progress into severe and often irreversible lung injury. Early phase: the misleading presentation After ingestion, patients may present with:
- Nausea and vomiting
- Oral and throat irritation
- Mild systemic symptoms
At this stage, the clinical picture can seem deceptively reassuring. But this is only the beginning. The hidden mechanism: selective lung toxicity
Paraquat has a unique property—it is actively taken up by alveolar cells in the lungs. Once inside, it undergoes redox cycling, producing reactive oxygen species (ROS).
These ROS:
- Damage cell membranes
- Disrupt mitochondrial function
- Trigger inflammation
The lungs, therefore, become the primary target of injury.
The turning point: delayed deterioration
Over the next few days, patients may begin to worsen:
- Increasing breathlessness
- Hypoxia
- Diffuse lung injury
Eventually, this can progress to pulmonary fibrosis and respiratory failure.
What makes this particularly dangerous is the delay—the gap between ingestion and severe symptoms.
What we can do.
1. Early decontamination: the critical window
If the patient presents early: Activated charcoal or Fuller’s earth can be administered. This helps reduce further absorption of paraquat from the gastrointestinal tract
Timing is crucial. Once absorbed, paraquat rapidly distributes to tissues—especially the lungs.
2. Limiting systemic toxicity
In some cases, Hemoperfusion may be used to remove circulating toxin
Most effective if initiated early
However, its benefit decreases significantly once paraquat has entered tissues.
3. Oxygen: a double-edged sword
One of the most unique aspects of paraquat poisoning is oxygen management. High oxygen concentrations can worsen lung injury. This is due to increased formation of reactive oxygen species
As a result: Oxygen is given only if necessary, and at the lowest effective concentration
4. Supportive and organ-directed care
As the disease progresses:
Fluid management for renal perfusion. Monitoring for acute kidney injury and liver dysfunction. Ventilatory support in cases of respiratory failure
Despite supportive care, progression to fibrosis can be difficult to reverse.
5. The harsh reality
Unlike many poisonings, there is no definitive antidote for paraquat.
This makes early recognition and intervention the most important factors influencing outcomes.
Clinical takeaway
Paraquat poisoning reinforces a critical principle in medicine:
When damage begins at the molecular level, timing becomes everything.
By the time symptoms worsen, much of the injury may already be underway
