Do any medications cause Parkinson's? Understanding Drug-Induced Parkinsonism

October 9, 2025 •

4 min read

Drug-induced parkinsonism (DIP) is the second most common cause of parkinsonism after idiopathic Parkinson's disease (PD), and cases can constitute a significant percentage of all parkinsonism syndromes. Understanding if and how any medications cause Parkinson's-like symptoms is critical for proper diagnosis and management.

Quick Summary

Certain medications, most notably those that block dopamine receptors, can cause a reversible syndrome called drug-induced parkinsonism (DIP), which mimics the motor symptoms of Parkinson's disease (PD).

Key Points

DIP is a reversible condition: Drug-induced parkinsonism mimics the motor symptoms of Parkinson's disease but is typically reversible upon discontinuation of the causative medication.
Antipsychotics are major culprits: First-generation antipsychotics like haloperidol and some second-generation antipsychotics such as risperidone and aripiprazole frequently block dopamine receptors, causing DIP.
Anti-nausea drugs are also implicated: Common antiemetics like metoclopramide and prochlorperazine, which also block dopamine, can lead to DIP.
Symptoms tend to be symmetrical: DIP often presents with symmetrical symptoms on both sides of the body, whereas idiopathic PD typically begins with asymmetrical signs.
Diagnosis involves medication review: A critical step in diagnosing DIP is to review the patient's medication history and observe if symptoms improve after the suspected drug is stopped.
Recovery timeline varies: While most people recover after discontinuing the offending drug, some may experience persistent symptoms for months. In rare cases, underlying PD may be unmasked.

What is Drug-Induced Parkinsonism?

Drug-induced parkinsonism (DIP) is a condition that features the same primary motor symptoms as Parkinson's disease (PD), but is a direct side effect of certain medications rather than a neurodegenerative disorder. It is caused by drugs that interfere with the brain's dopamine system, a neurotransmitter crucial for smooth, controlled movements. Unlike true PD, which involves the progressive death of dopamine-producing neurons, DIP is caused by a temporary pharmacological imbalance. The symptoms can develop rapidly, often within days to months of starting a new medication.

The prevalence of DIP is higher in older adults, likely because the brain's natural dopamine levels decline with age, making them more susceptible to the effects of dopamine-blocking agents. In some cases, the medication may not be the direct cause but rather “unmasks” an existing, but previously asymptomatic, neurodegenerative condition like PD. This makes proper diagnosis, which often involves discontinuing the potential offending drug, particularly important.

The Mechanisms Behind Drug-Induced Parkinsonism

The underlying mechanism for most cases of DIP involves the blockage of dopamine D2 receptors in the brain's motor circuitry. The basal ganglia, a group of structures involved in movement control, rely on dopamine to function correctly. When dopamine receptors are blocked, the brain's motor signals are inhibited, leading to the motor features of parkinsonism.

Drugs that block or deplete dopamine can cause this effect, including:

Dopamine-receptor antagonists: Many antipsychotics and antiemetics work by blocking dopamine D2 receptors to achieve their therapeutic effect.
Dopamine-depleting agents: Drugs like reserpine and tetrabenazine deplete dopamine stores within nerve endings.

Some atypical antipsychotics, such as clozapine and quetiapine, generally carry a lower risk of causing extrapyramidal symptoms compared to their typical counterparts. However, others like risperidone, aripiprazole, and olanzapine can still induce parkinsonism, especially at higher doses.

Medications That Can Cause Parkinson's-like Symptoms

Antipsychotics (Neuroleptics)

Typical Antipsychotics (First-Generation): These are the most common culprits for DIP due to their strong dopamine D2 receptor blockade.
- Haloperidol
- Prochlorperazine
- Fluphenazine
Atypical Antipsychotics (Second-Generation): Although designed to have a lower risk, they can still cause DIP, particularly at higher doses.
- Risperidone
- Olanzapine
- Aripiprazole
- Ziprasidone

Antiemetics (Anti-Nausea Drugs)

Metoclopramide (Reglan): A well-documented cause of DIP, often used for gastrointestinal issues. Its chemical structure is similar to that of some antipsychotics.
Prochlorperazine (Compazine): Another anti-nausea drug that blocks dopamine receptors and can cause parkinsonism.

Calcium Channel Blockers

Flunarizine and Cinnarizine: These are used for conditions like vertigo and migraines and are known to induce parkinsonism, especially with long-term use.

Antidepressants

SSRIs: Certain selective serotonin reuptake inhibitors have been linked to extrapyramidal symptoms, including those mimicking parkinsonism.
- Fluoxetine
- Sertraline
- Paroxetine
Tricyclic Antidepressants (TCAs): Some can also cause DIP.

Mood Stabilizers and Other Medications

Lithium: Used to treat bipolar disorder, lithium has been reported to cause DIP in some patients.
Valproic Acid: Used for epilepsy and mood disorders, chronic use can lead to parkinsonism. Withdrawal of the drug often resolves symptoms.
Tetrabenazine: A dopamine-depleting agent used to treat hyperkinetic disorders that can induce parkinsonism as a side effect.

Distinguishing Drug-Induced Parkinsonism from Parkinson's Disease

Differentiating DIP from PD can be challenging for clinicians, as their motor symptoms are nearly identical. A key tool in this diagnosis is the observation of clinical features and the patient's response to medication discontinuation. According to the American Parkinson Disease Association, symptom symmetry is a significant clue.

Comparison of DIP and PD


Feature	Drug-Induced Parkinsonism (DIP)	Idiopathic Parkinson's Disease (PD)
Symmetry	Often bilateral and symmetrical, affecting both sides of the body equally.	Typically starts asymmetrically, affecting one side of the body more than the other initially.
Onset	Usually rapid, within days to months after starting a causative drug.	Gradual and insidious, worsening over a period of years.
Non-Motor Symptoms	Generally absent, focusing primarily on motor symptoms.	Features a wider range of non-motor symptoms, like loss of smell (hyposmia), sleep disorders, and depression, which can appear years before motor symptoms.
Tremor	May include a resting tremor, but can also involve other types like postural tremor.	Characterized by a classic resting tremor that disappears with intentional movement.
Reversibility	Usually reversible within weeks to months after the offending drug is discontinued.	Progressive and irreversible, as it involves the ongoing loss of dopamine neurons.
Dopamine Transporter (DaT) Scan	Normal, reflecting the temporary blockade of receptors.	Abnormal, showing a loss of dopaminergic neurons.

Conclusion

While certain medications can cause Parkinson's-like symptoms, it is important to distinguish this reversible syndrome—drug-induced parkinsonism—from the progressive neurodegenerative condition of Parkinson's disease. DIP is most often caused by dopamine-blocking drugs, such as certain antipsychotics and anti-nausea agents. In most cases, symptoms will resolve once the offending medication is discontinued or replaced, though recovery can take several months. DIP can be especially challenging to diagnose because it may sometimes occur in individuals who have preclinical PD, with the medication simply unmasking an underlying condition. For any patient developing parkinsonian symptoms, a thorough review of all current and recent medications is a crucial step in reaching an accurate diagnosis and determining the correct course of action.

Frequently Asked Questions

Drug-induced parkinsonism (DIP) is a syndrome featuring motor symptoms like those of Parkinson's disease (PD), including tremor, stiffness, and slow movement, caused by a reaction to certain medications.

The most common culprits are dopamine-blocking agents, including antipsychotic drugs (e.g., haloperidol, risperidone), anti-nausea medications (e.g., metoclopramide), and some calcium channel blockers (e.g., flunarizine).

Yes, some antidepressants, particularly certain selective serotonin reuptake inhibitors (SSRIs) like fluoxetine and sertraline, have been reported to cause or worsen parkinsonism in some individuals.

No, in most cases, DIP is reversible. Symptoms typically improve or resolve completely within weeks to months after the offending medication is discontinued, though sometimes symptoms may persist for longer periods.

Key differences include DIP’s more rapid onset and tendency to affect both sides of the body symmetrically, unlike the gradual, asymmetrical start of PD. Unlike DIP, PD also features a wide range of non-motor symptoms, and is a progressive disease.

The primary treatment is to discontinue the medication causing the symptoms, under a doctor's supervision. If stopping the drug is not possible, the dosage may be adjusted, or an alternative medication with fewer extrapyramidal effects may be used.

Yes. In some instances, a patient may have early, subclinical Parkinson's disease, and the dopamine-blocking effects of a medication can trigger or worsen symptoms, thereby unmasking the underlying condition.

No, not all antipsychotics carry the same risk. While typical antipsychotics are high-risk, some atypical antipsychotics like clozapine and quetiapine have a lower risk profile for causing parkinsonism.