From the Guidelines
Ivermectin toxicity is a serious condition that can occur when the medication is taken in excessive doses or in individuals with high L. loa microfilaria loads, and immediate medical attention is necessary to manage symptoms and prevent severe adverse events, including death. The risk of severe adverse events is high when the microfilaria load exceeds 8000 microfilaria/ml, and the reaction is more severe if the load exceeds 30 000 microfilaria/ml 1. Symptoms of ivermectin toxicity include neurological adverse events, such as seizures, and in severe cases, death.
Causes and Risk Factors
The causes of ivermectin toxicity include:
- Taking excessive doses of the medication
- Having high L. loa microfilaria loads, particularly in areas co-endemic with onchocerciasis
- Using veterinary formulations for human use
- Inadequate storage of the medication, leading to accidental ingestion by children
Prevention and Management
Prevention involves:
- Using ivermectin only as prescribed by healthcare providers
- Avoiding veterinary formulations for human use
- Storing the medication safely away from children
- Conducting thorough screening for L. loa microfilaria loads before initiating ivermectin treatment in areas co-endemic with onchocerciasis Management of ivermectin toxicity is primarily supportive, focusing on symptom management, and may involve:
- Discontinuing the medication immediately
- Providing emergency medical care, including hospitalization and close monitoring
- Administering medications to manage symptoms, such as anticonvulsants for seizures
Outcome and Prognosis
The outcome and prognosis of ivermectin toxicity depend on the severity of the condition, with higher doses and higher microfilaria loads associated with more severe symptoms and poorer outcomes 1. Recovery typically occurs within days to weeks, depending on the severity of the condition, though some neurological symptoms may persist longer. It is essential to prioritize caution when using ivermectin, particularly in areas co-endemic with onchocerciasis, to minimize the risk of severe adverse events and ensure the safe and effective use of this medication.
From the FDA Drug Label
OVERDOSAGE Significant lethality was observed in mice and rats after single oral doses of 25 to 50 mg/kg and 40 to 50 mg/kg, respectively. No significant lethality was observed in dogs after single oral doses of up to 10 mg/kg. At these doses, the treatment-related signs that were observed in these animals include ataxia, bradypnea, tremors, ptosis, decreased activity, emesis, and mydriasis In accidental intoxication with, or significant exposure to, unknown quantities of veterinary formulations of ivermectin in humans, either by ingestion, inhalation, injection, or exposure to body surfaces, the following adverse effects have been reported most frequently: rash, edema, headache, dizziness, asthenia, nausea, vomiting, and diarrhea Other adverse effects that have been reported include: seizure, ataxia, dyspnea, abdominal pain, paresthesia, urticaria, and contact dermatitis. In case of accidental poisoning, supportive therapy, if indicated, should include parenteral fluids and electrolytes, respiratory support (oxygen and mechanical ventilation if necessary) and pressor agents if clinically significant hypotension is present Induction of emesis and/or gastric lavage as soon as possible, followed by purgatives and other routine anti-poison measures, may be indicated if needed to prevent absorption of ingested material.
- Ivermectin toxicity can cause significant adverse effects in humans, including:
- Rash
- Edema
- Headache
- Dizziness
- Asthenia
- Nausea
- Vomiting
- Diarrhea
- Seizure
- Ataxia
- Dyspnea
- Abdominal pain
- Paresthesia
- Urticaria
- Contact dermatitis
- Treatment for accidental poisoning should include supportive therapy, such as:
- Parenteral fluids and electrolytes
- Respiratory support (oxygen and mechanical ventilation if necessary)
- Pressor agents if clinically significant hypotension is present
- Induction of emesis and/or gastric lavage as soon as possible, followed by purgatives and other routine anti-poison measures 2
From the Research
Ivermectin Toxicity Overview
- Ivermectin is an antiparasitic drug that has been used as an alternative for prophylaxis and treatment of COVID-19 infection 3.
- The adverse effects from supratherapeutic doses of ivermectin can include non-neurological and neurological symptoms 3.
Clinical Effects of Ivermectin Toxicity
- Clinical effects of ivermectin toxicity include neurotoxicity, gastrointestinal symptoms, and musculoskeletal complaints 4.
- Neurological toxicity is the most frequent finding, with patients experiencing altered mental status, restlessness, and complex visual hallucinations 3, 4, 5.
- Patients taking veterinary formulations of ivermectin are at higher risk of developing neurotoxicity due to higher doses 4.
Risk Factors for Ivermectin Toxicity
- Patients >60 years old who ingest higher than recommended doses of ivermectin are at higher risk of developing toxicity 4.
- Self-medication with veterinary formulations of ivermectin increases the risk of toxicity 5.
- Chronic ingestion of ivermectin, even at therapeutic doses, can lead to toxicity due to prolonged exposure 4.
Treatment and Outcome of Ivermectin Toxicity
- Treatment of ivermectin toxicity typically involves administration of activated charcoal and supportive care 3.
- Clinical outcome in patients with ivermectin toxicity can be improved with prompt medical attention and treatment 3, 4, 5.
- Severe adverse events, including death, have been reported in cases of ivermectin toxicity 4, 5.