EMA Reviews Deworming Drug Levamisole Over Brain Side Effects: What You Need to Know

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The European Medicines Agency (EMA) is currently reviewing the safety of the deworming drug levamisole amid growing concerns about its possible link to a serious brain disorder called leukoencephalopathy. This safety evaluation, initiated in 2025, follows reports of debilitating neurological side effects, including one death, that may arise after levamisole use. The review is a significant development in the ongoing monitoring of medicines used to treat parasitic worm infections in the European Union (EU).

What Happened:

Levamisole, marketed in some EU countries under names such as Decaris and Levamisol Arena, is an anthelmintic medicine authorized for treating parasitic worm infections in adults and children in Hungary, Lithuania, Latvia, and Romania. The National Agency for Medicines and Medical Devices of Romania (NAMMDR) raised concerns due to recent cases of leukoencephalopathy allegedly linked to this drug, prompting review by EMA’s Pharmacovigilance Risk Assessment Committee (PRAC).

Leukoencephalopathy is a rare but potentially life-threatening brain disease characterized by damage to the brain’s white matter — nerve fibers covered by a protective myelin sheath. Symptoms include confusion, muscle weakness, coordination problems, speech and vision impairments, and in severe cases, death. The PRAC review aims to critically assess available evidence to determine whether the benefits of levamisole outweigh its risks and if regulatory actions are needed across the EU.

Key Findings and Background

Levamisole, discovered in 1966, initially used in veterinary medicine, was approved for human use later but was withdrawn from many countries, including the US, Canada, and parts of Europe around 2000 because of safety concerns including neurological adverse effects. Despite this, it remains authorized in select EU countries.

Recent safety monitoring uncovered several serious cases of leukoencephalopathy following levamisole administration, including one fatality. Literature reviews and case studies highlight that even a single dose of levamisole might lead to severe brain injury, prompting researchers to call for stringent medication management to prevent uncontrolled use.

Leukoencephalopathy results from demyelination—the loss of myelin in the brain and spinal cord—which disrupts nerve function. The disorder is particularly challenging because early symptoms such as confusion or weakness can be mistaken for other conditions. Treatments reported in case series, including intravenous corticosteroids and plasma exchange, have sometimes improved outcomes but neurological symptoms may persist in some patients.

Expert Perspectives

Dr. Anne Schmidt, a neurologist at a major European university hospital who is not affiliated with the EMA review, commented: “Leukoencephalopathy is a serious condition that can have devastating consequences if not promptly diagnosed and managed. The concerns raised about levamisole are valid, especially given its mechanism affecting neural pathways. Regulatory agencies must carefully balance treatment benefits in parasitic infections with these rare but severe side effects.”

Similarly, Dr. Marco Rossi, an infectious disease specialist, noted: “While levamisole has been a useful tool in treating certain parasitic infections, this new safety signal demands revisiting treatment guidelines and considering alternative medicines with better safety profiles where available.”

Context: Deworming Drugs and Neurological Risks

Deworming medications such as albendazole, mebendazole, ivermectin, and levamisole are critical in controlling parasitic infections that affect millions worldwide. Generally, these drugs are considered safe when used appropriately, though neurological side effects are rare and vary by drug and population.

For instance, ivermectin has been linked to serious neurological effects such as encephalopathy in individuals with very high parasitic loads of Loa loa, a filarial worm common in Sub-Saharan Africa. Cases include symptoms like fever, fatigue, and altered consciousness. These reactions are explained by the drug’s rapid killing of parasites and associated inflammation in the brain.

Albendazole and mebendazole are generally well tolerated, with mild side effects reported. However, in neurocysticercosis (brain infection by tapeworm larvae), patients may experience increased intracranial pressure or seizures during treatment.

Levamisole’s safety profile raises a red flag due to the severity of neurological injury reported, underlying why EMA’s review is critical for patient safety.

Public Health Implications

Parasitic worm infections remain a global health challenge, particularly in low-resource settings, affecting children’s growth, nutrition, and cognitive development. Deworming programs are widely implemented because of their public health significance.

The EMA’s current levamisole review highlights an essential tension in public health: ensuring access to effective antiparasitic treatments while safeguarding against potential harms. Regulatory decisions based on this review could lead to changes in authorization status across EU countries, potentially limiting levamisole availability or imposing stricter usage guidelines.

For prescribers and patients, this means informed discussions about treatment options, side effect risks, and monitoring. In the meantime, vigilance for neurological symptoms during and after deworming treatment with levamisole is prudent.

Limitations and Counterarguments

While the reported cases are serious, leukoencephalopathy remains a rare adverse event, and definitive causal links can be challenging to establish given the complexity of clinical presentations and confounding factors. Some experts caution that abandoning effective deworming drugs without adequate alternatives could worsen parasitic disease burdens.

Further data from ongoing pharmacovigilance and clinical studies will be crucial to clarify risk magnitude and identify patient groups most at risk. The EMA’s measured approach of benefit-risk reassessment aims to arrive at evidence-based recommendations while avoiding unnecessary alarm.

Conclusion

The EMA’s 2025 review of levamisole’s safety underlines the importance of continuous drug monitoring and regulatory vigilance. It serves as a reminder that medicines once deemed safe can reveal serious side effects with widespread use and time. For the public and healthcare providers, it reinforces the need for balanced understanding and cautious use of all medications, even those long available.

Medical Disclaimer

This article is for informational purposes only and should not be considered medical advice. Always consult with qualified healthcare professionals before making any health-related decisions or changes to your treatment plan. The information presented here is based on current research and expert opinions, which may evolve as new evidence emerges.