Medication Induced Parkinsonism [Avoid these medications if you have Parkinson’s!]

Certain medications block dopamine activity in the brain.

  • If you don’t have Parkinson’s, they may cause Medication Induced Parkinsonism (also called “drug-induced parkinsonism”).
  • If you have Parkinson’s disease, they can worsen your symptoms.

In this condition, Levodopa is not very useful. This is because the sites where levodopa normally attaches are blocked by these nefarious drugs.

Therefore, in this condition, both Anticholinergic medications and Amantadine are more effective than levodopa.

Let us learn more.

Dopamine Blockers

First, here are the medications that can block Dopamine activity in the brain.

DOPAMINE BLOCKERS: Medications which can produce symptoms like Parkinson’s disease

Many medications used for psychiatric problems such as schizophrenia (these are also called “Neuroleptics”)Haloperidol, Risperidal, Olanzapine, Aripiprzole, Trifluoperazine and many more. Clozapine and Quetiapine usually do not cause problems.
Some medications for mood and depressionFluphenazine, Tranycypormine, Lithium
Some anti-nausea medicationsMetoclopramide, Levosulpuride, High doses of domperidone about 30-40 mg/day, Flunarazine, rarely cinnarazine
Some heart and blood pressure medicationsAmiodarone, methly-dopa

Overall, Neuroleptics (psychiatric) medications are probably the most common cause of Medication Induced Parkinsonism.

What is Parkinsonism?

Parkinsonism literally means “like Parkinson’s disease”.

Certain symptoms usually are seen in Parkinson’s disease. If a person has these symptoms, he is said to have Parkinsonism.

Parkinson’s disease is the most common cause of Parkinsonism.

The second most common cause in many countries is Medication Induced Parkinsonism.

What is Dopamine Blockade?

Dopamine is a chemical in our brains. It helps us to move.

Medication Induced Parkinsonism is caused by medications which block the action of dopamine.

These nefarious medications do this by blocking the microscopic sites in the brain where dopamine usually attaches itself. There is no death of cells.

Dopamine Blockade
Dopamine-blocking medications block the sites in Brain cells where Dopamine normally attaches. Now, dopamine cannot attach itself anywhere! It stops having any effect! The cells do not die.

On the other hand, in typical Parkinson’s disease, there is the actual death of cells in the Substantia Nigra (Click Here).

Therefore, these processes are very different from one another.

In addition, the symptoms produced by “Medication Induced Parkinsonism” are also somewhat distinct. There is usually no tremor and both sides are equally affected. Medication Induced Parkinsonism can progress very rapidly, whereas Parkinson’s disease usually progresses very slowly.

Why is levodopa not useful in Medication-Induced Parkinsonism?

Levodopa gets converted into dopamine in the brain. But then it has nowhere to attach!

Once it enters the brain, Levdoopa is converted into Dopamine.

Therefore, levodopa is not very useful in medication-induced Parkinsonism.

Anti-cholinergic medications

Dopamine has an enemy in the brain, called Acetylcholine. Acetylcholine actually is a good chemical with a lot of beneficial effects, but one of the things it does is to reverse some of the actions of Dopamine.

Trihexyphenidyl (Pacitane) and Benztropine are the most commonly used Anticholinergic Medications.

By decreasing the effect of acetylcholine (dopamine’s enemy), these medications give Dopamine a free hand in the brain.

Anti-cholinergic medications: Side effects

I (and many other doctors) believe that Trihexyphenidyl (Pacitane) and related medications should not be used in the elderly, at least not routinely. Acetylcholine is a very important chemical in the body, and blocking it can produce many unwanted side-effects.

Therefore the most common, and frequently serious side-effects with the use of these medications are:

  1. Confusion – The patient may lose track of day and night. He/She gets confused easily, has trouble paying attention or remembering anything. In very severe cases, the patient can have visual hallucinations and become physically violent!
    Anticholinergics can cause confusion.
  • Acute urinary retention – This happens more frequently in males. The urinary bladder fills up with urine, but because of the anticholinergics, the path for urine to get out is closed! The patient starts becoming very, very uncomfortable because of the ever-increasing size of the bladder, which causes severe abdominal pain. This sometimes requires the urgent insertion of a catheter.
  • Glaucoma – Similar to what happens with urine, these medications can cause shut off the flow of fluid away from the eye. They make the pupil very large, blocking all the drainage pipes in the periphery of the eye. As a result, fluid keeps accumulating within the eye, and it starts becoming larger. The eye is not a very flexible, and therefore the pressure inside it increases rapidly, and this can cause severe eye pain and blindness. Immediate medical treatment is needed!
    Sometimes, anticholinergics can cause “Glaucoma” – which is an uncontrolled increase in pressure inside the eye.


Is Amantadine a better treatment for medication-induced Parkinsonism?

Yes, I think so.

I think so because it is equally effective and the side-effects of amantadine are relatively modest.

In patients without kidney disease, Amantadine usually does not have any side-effects other than some minor leg swelling and redness.

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Amantadine was originally made to treat viral colds. Incidentally, doctors found it to be a stellar medication for Parkinson’s disease, including medication-induced Parkinsonism.

One has to be careful while using it in patients with renal failure. Amantadine is excreted by the kidneys and therefore it accumulates in the body if you have renal failure. If it accumulates up to a toxic level, you may become confused and have jerking of the body (myoclonus).


Does the development of “Medication Induced Parkinsonism” predict the development of “Parkinson’s disease” later in life?

No, not in the majority of cases.

However, some patients have a dopamine deficiency and are on the brink of developing symptoms due to Parkinson’s disease. If a person is on the brink of developing symptoms, dopamine-blocking medications lead to appearance/worsening of Parkinsonian symptoms.

In these patients, dopaminergic blocking medications may cause sudden appearance/worsening of these symptoms.

Physical therapy, especially balance training, can help to delay onset of Parkinson’s disease.

So, in some (but not all) cases, the development of medication-induced parkinsonism may indicate that the patient may develop Parkinson’s disease later in life.


Caution: This information is not a substitute for professional care. Do not change your medications/treatment without your doctor's permission.
Dr. Siddharth Kharkar

Dr. Siddharth Kharkar

Dr. Siddharth Kharkar has been recognized as one of the best neurologists in Mumbai by Outlook India magazine and India today Magazine. He is a board certified (American Board of Psychiatry & Neurology certified) Neurologist.

Dr. Siddharth Kharkar is a Epilepsy specialist in Mumbai & Parkinson's specialist in Mumbai, Maharashtra, India.

He has trained in the best institutions in India, US and UK including KEM hospital in Mumbai, Johns Hopkins University in Baltimore, University of California at San Francisco (UCSF), USA & Kings College in London.

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NeuroPlus Epilepsy & Parkinson's Clinic - Dr. Kharkar IconNeuroPlus Epilepsy & Parkinson's Clinic - Dr. Kharkar

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  • Avatar Paras Prabhu ★★★★★ 6 months ago
    Out patient is epileptic from about 10 years and her seizure gotten worse during the past year with the frequency of about 3-4 times a week.So we consulted … More Dr. Kharkar. He tried a few medicines, and within 1.5-2 months now the patient is feeling very well now. There are no seizures for 14 days currently.Dr. tried to keep medicines as minimum as possible. He also tried to keep the cost of the treatment minimum.When some of the medicines started showing side-effects, he was quick to switch the medicines to the better options.Overall I think we are getting a best of the available treatments. We thank you very much Dr. Kharkar.
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    Dr Kharkar is gem of a doctor with tremendous patience, empathy, genuine concern for his patients .He guides them very methodically & scientifically … More for their neurological ill healthOur epilepsy patient is extremely happy with his treatment , Patient feels better by just visiting him too!May his selfless service to humanity flourish to reach all the needy patients!!
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    I consulted Dr Sidharth for my sister who has become very hyper and aggressive and we could not understand the issue. Keeping in mind she is someone with … More special needs Dr Sidharth was extremely understanding of the situation and did not put her through unnecessary investigation and avoided a very long stay at the hospital. He was infact more keen on her returning home to her natural environment. We highly appreciate Dr Sidharth for his effort and for looking into the matter with utmost care. It was a very difficult decision for my family to get my sister admitted but we are glad we did it under his care.Thankyou Doc.
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    my name is prashant purohit. I m become completely bed ridden from last 9 months and was unable to walk. I couldnt find out the cause even after visiting … More many doctors and many hospital in Ahmedabad nd jodhpur.started losing hope. A good friend of mine suggested to visit a neurologist. After searching a lot, I came to know about Dr. Siddharth Kharkar and took his appointment in Nanavati Hospital. He examined and said that he suffered from \u201cPKD(PAROXYSMAL KNESIGENIC DYSKNESIA\u201c. He assured us to reverse this in 5 days time. And indeed this happened. I started recovering miraculously. today I am fully well fit I m walking as normal . Many Many thanks to Dr. Siddharth Kharkhar sir for giving me a new life.
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    Dr. Kharkar is truly exceptional. He is extremely knowledgeable. But simultaneously, he is extremely patient and kind - taking the time and care to respond … More to all the questions. It is rare to come across a doctor who is not in a hurry to get on to the next patient, but instead, focuses on the one in front with full attention, expertise and compassion. A great experience.
  • Avatar N N ★★★★★ a year ago
    We visited Dr. Kharkhar for treatment regarding my mum - who is a multi-stroke patient and has aphasia. Certain medications were creating complications … More with her condition and Dr. Kharkhar was able to help mitigate the issue. We found him and his approach to be incredibly compassionate, considerate, individualized and patient-friendly. He advice is astute, up-to-date and empathetic. His treatment always comes from a deeply human place and is about seeing how to help the patient and their caregivers feel more at ease. Something that is quite rare and refreshing within the medical community.We feel that he genuinely cares about the patients that he is treating and is always kind and respectful in his communication. Moreover, his admin team is very efficient and prompt and it's a pleasure to deal with them.Would highly recommend Dr Kharkhar himself - though we must say our experience with Nanavati hospital itself has been less than ideal.Hope this helps.
  • Avatar Manish Ranjan ★★★★★ a year ago
    I have been visiting Dr Kharkar for treatment of my father. He is a very friendly doctor. He listens to our concerns with lot of patience. He also explains … More the issue in much greater details. He has really been of great help. My father is much better now.
  • Avatar Pinakin Shah ★★★★★ a year ago
    One of the best Dr. Gives complete attention and time to listen to patient's history, issues. Explains various options of treatment with pros and … More cons.
  • Avatar Lawrence Castellino ★★★★★ a year ago
    Exceptional experience with an expert,Dr. Kharkar is a knowledge house. It is rare nowadays to find doctors with patience, knowledge, and a flair for … More handling patient’s questions, besides Dr. Kharkar’s bedside manners are exemplary. I am privileged to be treated by such an amazing soul. I have told him and will repeat it here that “I am advancing my move back to India although I am a US Citizen, because I know I am in good hands and will be well taken care of. Thanks Dr. Kharkar for your selfless service!
  • Avatar Hemant Kansara ★★★★★ a year ago
    Great doctor!! Really appreciate.The doctor diagnosed to my sister correctly and start treatment, she has good improvement after taking medicine prescribed … More by doctor as no epilepsy attake. We have good experience with the doctor. Thank you

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Noted as one of the best Neurologists in Mumbai

India Today Magazine - 2020, 2021, 2022, 2023

Outlook India Magazine - 2021, 2023

Ex-Assistant Professor, University of Alabama, USA

Outlook India - Best neurologist in Mumbai