What is the toxic dose of spearmint (Mentha spicata) essential oil that can cause an overdose?

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Last updated: May 16, 2025View editorial policy

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From the Research

Spearmint oil can be toxic if ingested in large amounts, with a potentially lethal dose estimated at around 2-5 grams (approximately 2-5 mL) for adults, though sensitivity varies between individuals. Symptoms of spearmint oil overdose include nausea, vomiting, dizziness, slowed breathing, seizures, and in severe cases, coma or death. The toxicity stems from menthol and other compounds in the oil that can affect the central nervous system and irritate the gastrointestinal tract. Children are particularly vulnerable to smaller amounts. If you suspect someone has ingested too much spearmint oil, seek immediate medical attention rather than attempting home treatment. For safe use, always dilute essential oils properly, keep them away from children, and follow product guidelines. Therapeutic applications typically use much smaller amounts, often just a few drops diluted in carrier oils or other substances.

According to the most recent and highest quality study available, which is the review of the traditional uses, phytochemistry, and pharmacology of spearmint (Mentha spicata L.) 1, the essential oils and extracts of spearmint have shown remarkable antimicrobial, antioxidant, anticancer, anti-inflammatory, and hepatoprotective activities. However, the study also highlights the need for more research, especially in vivo experiments and clinical trials, to evaluate the cellular and molecular mechanisms based on pharmacological, bioactive effectiveness, and safety investigation.

Some key points to consider when using spearmint oil include:

  • Always dilute essential oils properly before use
  • Keep essential oils away from children
  • Follow product guidelines for safe use
  • Be aware of the potential for toxicity and overdose
  • Seek medical attention immediately if symptoms of overdose occur

It's also important to note that while peppermint oil has been studied for its potential benefits in relieving nausea and vomiting in hospitalized patients 2, the safety and efficacy of spearmint oil for this purpose is not well established. Therefore, it's essential to consult with a healthcare professional before using spearmint oil for any therapeutic purpose.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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