Navigating Contraindications with Parkinson’s Medications: A Practical Guide

Living with Parkinson’s means managing not only your symptoms but also ensuring that your treatment plan is as safe and effective as possible. An essential part of this is understanding contraindications—situations or conditions where certain medications may do more harm than good—and being aware of potential interactions, especially with over-the-counter supplements or vitamins. In this guide, we explore the common contraindications with Parkinson’s medications and provide practical steps to safeguard your treatment.

What Are Contraindications?

Contraindications are conditions or factors that serve as warnings, advising against using particular medications because they might cause adverse effects. In the context of Parkinson’s treatment, contraindications can relate to:

  • Existing Health Conditions: Certain medications may aggravate other health issues. For example, anticholinergic drugs, which are sometimes used to manage tremor, can worsen glaucoma or urinary retention.
  • Medication Interactions: Parkinson’s medications, such as levodopa, dopamine agonists, MAO-B inhibitors, and others, are designed to work in a specific way. Introducing other medications or supplements that interact with these can lead to reduced efficacy or even dangerous side effects. See APDA’s medications to avoid here. 
  • Individual Patient Factors: Each person’s response to medication can differ; brain chemistry and gut motility can affect this. Age, other chronic conditions, or your overall health may dictate which delivery methods and treatments are safe and appropriate.

Common Contraindications with Parkinson’s Medications

Here are some of the most common contraindications and interactions that you should be aware of:

  • Interactions with Supplements and Vitamins
    • Herbal Supplements and Natural Remedies: Some herbal supplements may interact with Parkinson’s medications. For instance, supplements that affect liver enzymes could alter the metabolism of drugs like levodopa, potentially leading to higher levels in your blood than anticipated. St John’s Wort is not recommended for people taking Parkinson’s medications.
    • Vitamins in High Doses: While a balanced intake of vitamins is essential, high doses may interfere with the effectiveness of your medication. For example, excessive vitamin B6 (pyridoxine) has been known to reduce the efficacy of levodopa unless it is counterbalanced by carbidopa.
    • Other Supplements: Iron tablets can also affect how much Levodopa is absorbed in the body and may cause or worsen constipation. Seek advice from your care team and aim to leave around 2 hours between taking iron supplements and Levodopa. Formulations also matter, e.g. magnesium oxide can significantly reduce c/l absorption.
    • Seek Advice: Always discuss any supplements or vitamins with your Parkinson’s Nurse Specialist, GP, or pharmacist before starting them. They can help determine what is safe and compatible with your current treatment plan.
  • Food-Drug Interactions
    • Protein Interference: High-protein meals can compete with levodopa for absorption in the gut, leading to reduced efficacy of the medication. For example a milky coffee, eggs and toast for breakfast is best saved for an hour after taking your pill on an empty stomach with a full glass of water or juice. If you take your pill before going out for a big meal, just be prepared for that “off” time. Some people choose to move the balance of their protein intake towards the end of the day when you can rest and go to bed. DO NOT eliminate protein from your diet. Seek advice and meal plans from an accredited Dietitian.
    • Tyramine-Rich Foods: When on MAO-B inhibitors, consuming foods high in tyramine (such as aged cheeses or cured meats) can potentially trigger dangerous spikes in blood pressure.
    • Seek Advice: Your care team can provide dietary guidelines designed to complement your medication schedule and improve treatment outcomes.
  • Interactions with Other Medications
    • Psychiatric Medications: Some medications, particularly those affecting dopamine pathways (such as certain antidepressants or antipsychotics), may counteract the benefits of Parkinson’s medicines or worsen side effects like impulse control disorders (ICDs). For example, antipsychotic medications block dopamine receptors in the brain, worsening a person’s Parkinson’s symptoms. These typical antipsychotics include: chlorpromazine (Thorazine), fluphenazine (Prolixin), haloperidol (Haldol), loxapine (Loxitane), thioridazine (Mellaril), thiothixene (Mellaril), trifluoperazine (Stelazine), pimozide (Orap), and perphenazine (Trilafon). Antipsychotics can also cause Parkinson’s-like symptoms or interact with Parkinson’s drugs.
    • Laxatives: Some laxatives can interact with Parkinson’s medications, so it’s important to be aware of potential interactions e.g. those with magnesium oxide.
    • Cardiovascular Medications: Since many Parkinson’s medications can influence blood pressure and heart rate, combining them with blood pressure medications may require careful monitoring.
    • Muscle Relaxants: The ADPA recommends avoiding the muscle relaxant cyclobenzaprine if taking selegiline, rasagiline, or safinamide. Taking cyclobenzaprine at the same time as, or within 14 days of stopping, MAOIs have caused hyperpyretic or abnormally high fever, crisis seizures, and death in some people.
    • Cold and Flu Medications: Decongestants and cold remedies can stop your Parkinson’s medication working properly and can also increase the risk of side effects (e.g. Lemsip). This is especially important to remember if you are taking selegiline, rasagiline and safinamide.
    • Anti-sickness drugs: Some Parkinson’s medication can cause nausea and vomiting. GPs usually prescribe domperidone (Motilium) to prevent and treat this side effect. But some anti-sickness drugs will interact with Parkinson’s drugs. These include metoclopramide (Maxalon) and prochlorperazine (Stemetil). Other anti-sickness drugs that are generally considered safe include cyclizine (Valoid) and 5-HT3 receptor antagonists like ondansetron.
    • Seek Advice: Always ensure your healthcare providers have a complete list of your medications—prescription, non-prescription, and over-the-counter—to avoid harmful interactions. Ask your pharmacist if you are in doubt. This medication list is not intended to be complete and additional brand names may be found for each medication.

Please take note

  1. Every person is different, and you may need to take one of these medications despite caution against it. Please discuss your particular situation with your GP and do not stop any medication that you are currently taking without first seeking advice. Most medications should be tapered off and not stopped suddenly to avoid withdrawals or serious health effects.
  2. Although you may not be taking contraindicated medications at home, one of these medications may be given to you while hospitalised. See our hospital medication checklist here to download and take with you.
  3. If you’re interested in learning what your vitamin levels are and whether you should take a daily supplement to raise them, talk to your GP about doing a blood test to see what you are actually low in.

What you should do

  • Keep a Medication Diary
    • Track your symptoms and any side effects you notice. This record can be extremely useful during consultations with your neurologist or pharmacist.
  • Maintain Open Communication
    • Always share when you are taking or want to take any new supplements, vitamins, or over-the-counter medications with your care team. Transparency is crucial.
  • Schedule Regular Reviews
    • Ask about Home Medicines Reviews so that a qualified pharmacist can assess your treatment plan on a periodic basis.

The Role of Home Medicines Reviews (HMRs)

Given the complexity of managing multiple medications, Home Medicines Reviews (HMRs) can be an invaluable tool in your treatment plan. An HMR involves a pharmacist visiting your home to review all the medications and supplements you’re taking. Here’s why HMRs are so beneficial:

  • Individualised Review: A pharmacist can assess your entire treatment regimen and find potential interactions or contraindications specific to your situation.
  • Ongoing Monitoring: As Parkinson’s is a progressive condition, your medication needs may change over time. Regular HMRs ensure that as your treatment plan evolves, new interactions or contraindications are identified early.
  • Collaboration with Your Care Team: HMRs create an opportunity for pharmacists, GPs, and Parkinson’s Nurse Specialists to collaborate closely, ensuring that you get the benefit of each specialist’s expertise.
  • Empowerment Through Education: By understanding how and why these interactions occur, you and/or your care partner can become active participants in your treatment, leading to better-informed decisions and improved outcomes.

Managing Parkinson’s medications is a complex but critical part of your treatment journey. By understanding the common contraindications, being aware of potential interactions with supplements or vitamins, and working closely with your healthcare team through initiatives like Home Medicines Reviews, you can optimise your treatment plan and safeguard your health. Always ensure that any changes in your medication or supplement routine are discussed with those who know your case best. In doing so, you take an active role in managing your condition and ensuring the best possible quality of life.

References

Bitner A, Zalewski P, Klawe JJ, Newton JL. Drug Interactions in Parkinson’s Disease: Safety of Pharmacotherapy for Arterial Hypertension. Drugs Real World Outcomes. 2015 Mar;2(1):1-12. doi: 10.1007/s40801-015-0008-7. PMID: 27747611; PMCID: PMC4883207.

Michael J. Fox Foundation for Parkinson’s Research. (n.d.). Parkinson’s Treatments: Medication Interactions. Retrieved from https://www.michaeljfox.org/

National Institute for Health and Care Excellence. (2017). Parkinson’s disease in adults: Diagnosis and management (NICE guideline NG71). Retrieved from https://www.nice.org.uk/guidance/ng71

Parkinson’s UK https://www.parkinsons.org.uk/information-and-support/your-magazine/spotlight/can-other-drugs-affect-my-parkinsons-medication

The American Parkinson Disease Association (APDA) Meds to Avoid https://www.apdaparkinson.org/living-with-parkinsons-disease/treatment-medication/meds-to-avoid/

This article is intended to support you in making informed decisions about your treatment. Always consult with your healthcare providers—your neurologist, Parkinson’s Nurse Specialist, and pharmacist—for personalised medication advice tailored to your specific needs.

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