Understanding if Amantadine Causes Shaking and Other Movement Issues

October 11, 2025 •

4 min read

While most commonly known for treating movement disorders, research and postmarketing experience have shown that amantadine can, in some cases, cause abnormal movements, including shaking or myoclonus. It is crucial for patients and healthcare providers to understand this paradoxical risk when considering therapy.

Quick Summary

Amantadine is used to treat Parkinson's disease and drug-induced movement disorders, but it can paradoxically cause or worsen shaking, tremors, or other involuntary movements in some patients. Renal function, dosage, and individual patient factors influence this risk. The effect can also be a withdrawal symptom if the medication is stopped abruptly.

Key Points

Paradoxical Effect: While often used to treat tremors, amantadine can paradoxically cause or worsen involuntary shaking, known as myoclonus or tremors, in some individuals.
Dose-Dependent Risk: The risk of developing amantadine-induced shaking is often related to the dosage, with higher doses increasing the potential for adverse movement effects.
Renal Function is Key: As amantadine is eliminated by the kidneys, impaired kidney function can lead to drug accumulation and an increased risk of toxicity, including involuntary movements.
Abrupt Withdrawal is Dangerous: Suddenly stopping amantadine can trigger a withdrawal syndrome, which may include severe muscle stiffness, agitation, confusion, and worsening of motor symptoms, including shaking.
Monitoring is Essential: Close monitoring by a healthcare provider is necessary, especially for elderly patients or those with renal impairment, to watch for signs of movement issues or other side effects.
Management is Possible: If shaking occurs, a healthcare provider may adjust the dosage, taper the medication slowly, or change to an alternative therapy to manage the symptoms.

Can Amantadine Cause Involuntary Shaking or Tremors?

While amantadine is often prescribed to reduce movement problems in Parkinson's disease, it is well-documented that this medication can also cause or exacerbate certain involuntary movements, including shaking or tremors. This paradoxical effect is an important consideration for patients and clinicians, especially since it is more common in individuals with higher dosages, pre-existing conditions, or renal impairment. Understanding the underlying mechanisms and risk factors is key to managing this potential side effect effectively.

The Dual Nature of Amantadine's Effect

Amantadine's role in treating movement disorders is complex due to its multiple mechanisms of action. It is a dopaminergic agent, meaning it increases dopamine levels in the brain, which helps coordinate movement. It is also an N-methyl-D-aspartate (NMDA) receptor antagonist, and has effects on other neurotransmitter systems, such as serotonergic pathways. This combination of effects is believed to contribute to its dual-action profile.

Treatment for Parkinson's Dyskinesia: Amantadine can effectively reduce levodopa-induced dyskinesia, which are uncontrolled, involuntary movements that can develop in patients with Parkinson's disease. This is a major therapeutic use, particularly for extended-release formulations.
Treatment for Drug-Induced Parkinsonism: It is also used to treat extrapyramidal symptoms, including stiffness and shakiness, that are caused by certain antipsychotic medications.
Cause of Movement Issues: In contrast, postmarketing experience and case reports have detailed instances where amantadine is associated with new or worsened tremors, myoclonus (sudden, brief muscle jerks), and other involuntary muscle contractions.

Risk Factors and High-Risk Groups

Certain factors can increase a patient's risk of experiencing amantadine-induced shaking:

Higher Dosage: The risk of abnormal movements and other adverse effects, such as confusion and hallucinations, increases with higher dosages of amantadine. Clinicians often start with a low dose and titrate slowly to find the balance between therapeutic effect and side effects.
Renal Impairment: Amantadine is primarily excreted by the kidneys. For elderly patients and those with pre-existing kidney disease, the medication can accumulate in the body, leading to higher serum concentrations and an increased risk of toxicity, including involuntary shaking. Dose adjustments are crucial in these populations.
Underlying Medical Conditions: Patients with existing neurological conditions or advanced Parkinson's disease may be more susceptible to the central nervous system side effects of amantadine.
Abrupt Withdrawal: Stopping amantadine suddenly can trigger a withdrawal syndrome that includes agitation, confusion, and worsening motor symptoms, potentially including severe shaking and muscle rigidity, similar to neuroleptic malignant syndrome. A slow, gradual taper is recommended to prevent this.

Managing Amantadine-Induced Shaking

If a patient develops shaking or other movement issues while on amantadine, a healthcare provider can take several steps:

Evaluate for Overdose or Withdrawal: It is important to distinguish between toxicity and withdrawal symptoms, which can sometimes overlap.
Dose Adjustment or Discontinuation: If the dose is too high, reducing it may alleviate the problem. In some cases, the medication may need to be discontinued entirely.
Monitor Renal Function: Regular monitoring of kidney function, especially in older adults, helps prevent drug accumulation that can lead to toxicity.

Other Common and Serious Side Effects

It is important to be aware of other potential side effects associated with amantadine. Common side effects often include dizziness, dry mouth, nausea, and difficulty sleeping. More serious, though less common, side effects warrant immediate medical attention, as detailed in the table below.


Type of Side Effect	Amantadine Side Effects	Comparison to Other Medications (e.g., Levodopa)
Movement-Related	Can cause or worsen tremors, myoclonus, and involuntary muscle contractions; may treat dyskinesia.	Can be used to treat dyskinesia caused by levodopa; however, abrupt discontinuation of amantadine can worsen Parkinson's symptoms.
Neurological	Confusion, hallucinations, nightmares, dizziness, and agitation are potential side effects.	Levodopa and other dopaminergic agents also carry a risk of similar neuropsychiatric side effects.
Cardiovascular	Can cause orthostatic hypotension (dizziness upon standing) and swelling of the ankles or feet.	This is a common side effect of many dopaminergic and CNS-acting drugs; caution is advised with pre-existing heart conditions.
Other	Common side effects include dry mouth, constipation, and nausea. A net-like purplish skin discoloration (livedo reticularis) may also occur.	Side effect profiles differ significantly among Parkinson's medications; individual tolerability is key.

Conclusion

While amantadine is a valuable tool for managing Parkinson's symptoms and drug-induced movement disorders, its potential to cause or worsen shaking is a real and important consideration. This is particularly true for individuals with compromised renal function or those taking higher doses. The risk of severe movement issues and other adverse events increases significantly with abrupt discontinuation, highlighting the need for gradual dose reduction. As with any prescription medication, patients should maintain open communication with their healthcare providers about all side effects, both expected and unexpected, to ensure safe and effective treatment. For more comprehensive patient information, the Mayo Clinic provides a detailed resource on amantadine.

Frequently Asked Questions

Amantadine has complex actions on the brain's neurotransmitter systems, including both dopaminergic and glutamatergic pathways. While its primary goal is to balance these systems to reduce movement disorders, it can sometimes overstimulate or disrupt them in a way that creates or worsens involuntary movements like tremors or myoclonus.

Amantadine-induced abnormal movements, including shaking, are a known side effect reported in postmarketing experience but are less common than more typical side effects like dizziness or nausea. The risk increases with higher doses and in individuals with kidney problems.

Elderly patients and individuals with kidney disease are at a higher risk because they process the drug more slowly. This can lead to the medication accumulating in their system, increasing the likelihood of toxic side effects, including involuntary movements.

If you notice new or worsening shaking, contact your healthcare provider immediately. They can evaluate your symptoms and determine if a dose adjustment, a slow taper, or a change in medication is necessary.

Yes, abruptly stopping amantadine can cause a withdrawal syndrome that includes worsening of Parkinson's symptoms, muscle rigidity, and shaking. A gradual, medically supervised dose reduction is essential to prevent this.

Amantadine is used to treat Parkinson's, but the shaking it can cause is a side effect of the medication itself, not necessarily an aspect of the disease. In fact, amantadine can sometimes be used to treat other types of drug-induced movement disorders that mimic Parkinsonism.

Yes, other medications, particularly certain antipsychotics, can cause drug-induced movement disorders. This is why amantadine is sometimes prescribed to manage these very side effects.