Drug-induced parkinsonism: Everything to know

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Drug-induced parkinsonism is the second leading cause of secondary parkinsonism.

It occurs due to drugs or toxins blocking the dopamine receptors in the brain. This causes a syndrome that closely resembles the symptoms associated with Parkinson’s disease.

Learn more about Parkinson’s disease.

Drug-induced parkinsonism is not a diagnosis but a set of symptoms. Symptoms associated with the syndrome include:

• Tremors: Tremors refer to shaky or trembling motion in one or more parts of the body.
• Bradykinesia: Bradykinesia refers to slowed movements.
• Gait disturbances: These are changes in how a person walks or balance.
• Rigidity: Rigidity refers to stiffness in the muscles.

Various medications can cause drug-induced parkinsonism. For several years, experts associated the condition only with antipsychotics. However, additional reports have indicated that other medications also can cause this complication.

Anti-nausea and antipsychotics cause the majority of cases, according to older research. However, other medications can also lead to drug-induced Parkinsonism.

Antipsychotics

Healthcare professionals first began reporting the syndrome due to the use of antipsychotics. Doctors often prescribe these medications to treat conditions such as schizophrenia. They can also help manage symptoms from other conditions, such as autism spectrum disorder and Tourette’s syndrome.

Antipsychotics can cause a range of mild to potentially life threatening side effects. They can include:

• dry mouth
• weight gain
• constipation
• inflammation of the heart
• sexual dysfunction
• restlessness

Anti-nausea medications

There are several different types of medications that a doctor may recommend to help treat nausea. They can include:

• serotonin (5-HT3) antagonists
• steroids
• NK-1 receptor antagonists
• benzodiazepines
• dopamine antagonists
• olanzapine
• cannabinoids

Each can cause different side effects. However, not all anti-nausea medications can or will lead to Parkinsonism. Dopamine antagonists and antidepressants may lead to drug-induced Parkinsonism due to their effect on the dopamine receptors. If side effects occur, a doctor can often switch medications.

Calcium channel blockers

Calcium channel blockers help treat a variety of conditions, including hypertension, migraine, pulmonary hypertension, and angina.

They can cause different side effects in people who take them, which can include:

• bradycardia or a slower-than-normal heart rate
• constipation
• worsening heart issues
• headaches
• flushing
• lightheadedness
• peripheral edema or swelling in the limbs, such as the legs, feet, hands, or arms

Anticonvulsant medications

Anticonvulsant medications help with seizures associated with epilepsy. These medications help improve communication between the nerves in the brain. Experts recognize them as a potential cause of drug-induced Parkinsonism.

In addition, they may cause side effects, such as:

• sexual dysfunction
• fatigue
• blurred vision
• dizziness
• urinary retention
• stomach upset
• nausea

Gastrointestinal prokinetics

Gastrointestinal prokinetics are a group of medications that doctors use to treat different gastrointestinal (GI) motility issues. However, they are known to cause drug-induced parkinsonism.

Other side effects can include:

• Tardive dyskinesia: sudden, uncontrolled movements on the face or body
• Akathisia: inability to remain still
• Dystonia: neurological muscle disorder that causes slow, repetitive contractions or odd postures

Antidepressants

Doctors prescribe antidepressants to treat depression as well as other conditions. Antidepressant use can cause drug-induced parkinsonism in some people.

They may also cause side effects such as:

• headaches
• weight gain or loss
• loss of appetite
• dizziness
• trouble sleeping
• feeling agitated or anxious
• indigestion
• nausea

Toxin exposure

Exposure to toxins can also cause drug-induced parkinsonism.

A common toxic cause comes from exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Often people who misuse drugs can come in contact with this chemical.

Parkinsonism describes some of the more well-known symptoms of Parkinson’s disease, such as tremors, loss of balance, and trouble walking.

Parkinson’s disease is a form of primary parkinsonism. Drug-induced parkinsonism is a form of secondary parkinsonism.

Drug-induced parkinsonism can include tremors. Drug-induced tremors can appear similarly to those associated with drug-induced parkinsonism.

Some key differences that help distinguish drug-induced tremor include:

• Unilateral: happening only on one side
• Task-specific: only occurs during certain activities
• Position-dependent tremor: occurs when a person sits or stands in a certain position
• Sudden onset: occurs suddenly, possibly without warning
• Distractibility: involves taking the mind off it to help stop the tremors
• Arrest with contralateral movements: involves doing other motions to help stop the tremors

In many cases, weaning off the medication causing the drug-induced parkinsonism should reverse the effects.

Weaning off a medication may not always be the best option. People who have tried multiple medications for their underlying condition and found no relief with other medications may not want to stop using the medication.

A person should never stop using a medication without first speaking with a healthcare professional.

The following sections provide answers to frequently asked questions about drug-induced Parkinsonism.

What is the most common drug-induced Parkinsonism?

The two most common medications that can cause drug-induced Parkinsonism are antipsychotics and anti-nausea medications. Other potential causes include:

• antidepressants
• gastrointestinal prokinetics
• calcium channel blockers
• anticonvulsants

Is drug-induced Parkinsonism progressive?

In most cases, the symptoms associated with drug-induced Parkinsonism will remain the same. They will typically improve once a person stops taking the medication responsible for the syndrome. Less commonly, a person may experience worsening symptoms over time.

Drug-induced Parkinsonism is the most common form of secondary Parkinsonism. It is not a diagnosis but instead a group of side effects that include slowed movements, balance and gait issues, tremors, and stiffness.

Several medications can cause the symptoms to occur, including antipsychotics and anti-nausea medications.

If a medication causes the symptoms to occur, a person can discuss other treatment options with a doctor.