Essential Oil Safety Masterclass

2nd Edition

Essential oils are brimming with powerful constituents that can soothe the skin, speed up wound healing, ease pain, calm the mind, and much more. But with great power comes great responsibility because they can also cause skin irritation, sensitization, phototoxicity, and other preventable adverse reactions.

Robert Tisserand, the leading global expert on essential oil safety, will guide you through all the knowledge you need to make the safest decisions!

Includes: Inhalation safety, Skin Safety, Mitigating Cancer Risk Safety in Pregnancy, Childbirth and Breastfeeding.

Next Enrollment: OPEN with special offer 2026

 

Essential Oil Safety Masterclass 2e

Payment in full
US$560

  • One payment. 

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Essential Oil Safety Masterclass 2e

Payment plan
US$140/month

  • Four payments of $140 over 4 months

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Eight-week online certification course – instructed by the author of Essential Oil Safety and one of the world’s leading experts

You’ll discover how essential oils work in the body, identify constituents responsible for certain properties (beneficial or otherwise), evaluate risks against benefits, calculate proper percentages, and explore the science behind safety, and the reasoning behind safety guidelines. 

Whatever your level of knowledge, this Masterclass will enable you to make your own informed decisions about essential oils according to current evidence, clinical trials, and best practice. Stop second-guessing – confidently and safely create essential oil preparations for yourself, family and friends, and aromatherapy clients.

What You Get in the Masterclass

8 + 1 WEEKLY LESSONS
Access to nine (9) 60-minute recorded lessons – EO Safety Masterclass plus Oxidation and Shelf-life of EOs.

Q&A SESSIONS 
Four live Q&A sessions with Robert Tisserand

PRINTABLE COURSE MATERIAL
Extensive downloadable handouts and course notes with links to additional research and resources.

COHORT SUPPORT WITH REAL HUMANS
The tutors and team are here to support you through the whole course process, no AI bots, just humans. 

DEDICATED GROUP DISCUSSIONS
Access to our private online forum to ask questions and interact with Robert, the TI team, and classmates.

ONGOING COURSE ACCESS
Ongoing access to tutors for eight weeks after the last lesson, access to forums and recordings for six months after course completion. Printable materials with lifetime access.

FUTURE COHORT ACCESS 
You have access to any future course cohort for a small administrative fee.

ALUMNI COMMUNITY 
Access to Tisserand Institute alumni community for peer support and networking.

Join the class and learn how to assess risk

Robert Tisserand

Author | Speaker | Founder of Tisserand Institute

Robert is one of the world’s leading experts in aromatherapy with over 50 years of experience. He is a speaker, educator, author, and consultant on the science and benefits of essential oils and their safe and effective application. Robert has inspired audiences in the UK, USA, Canada, Australia, Brazil, Czech Republic, China, Hong Kong, Taiwan, Korea and Japan on topics ranging from the therapeutic foundations of essential oils to examinations on essential oils and the skin.

Robert wrote one of the first books to bring awareness to aromatherapy in 1977, The Art of Aromatherapy, and is a co-author of Essential Oil Safety (2nd Edition, 2014), a book that sets industry standards for the safe use of essential oils.

Full 2026 Schedule

Essential Oil Safety 2nd Edition (Starting January 13, 2026)

Weekly lessons are pre-recorded, and will be released at 8am PST each Tuesday. We will host 4 live Q&A sessions, listed in bold below, which begin at 10am Pacific time.

Lesson 1: January 13, 2026
Lesson 2: January 20, 2026
Live Q&A: January 22, 2026 at 10am PST
Bonus Lesson (Oxidation): January 26, 2026
Lesson 3: January 27, 2026
Lesson 4: February 3, 2026
Live Q&A: February 5, 2026 at 10am PST
Lesson 5: February 10, 2026
Lesson 6: February 17, 2026
Live Q&A: February 19, 2026 at 10am PST
Lesson 7: February 24, 2026
Lesson 8: March 3, 2026
Live Q&A: March 5, 2026 at 10am PST

Course Breakdown

Lesson 1 - The Importance of Safety

Why safety applies to all users of essential oils
Safety assessment
The difference between hazard and risk
Risk factors
Balancing risk and benefit

You will be able to:

  • Explain the need for safety awareness
  • Correctly identify risk factors
  • Explain the difference between hazard and risk
Lesson 2 - Inhalation and Diffusion

What happens in your body when you inhale essential oils
Potential adverse reactions and risk factors
Different means of diffusion and inhalation
Establishing safe and effective levels for diffusion
Diffusing in public spaces

You will be able to:

  • Identify respiratory conditions that increase risk
  • Link individual scenarios with appropriate modes of use
  • Determine safe essential oil use for given circumstances
Lesson 3 - Skin Irritation & Allergy

Skin and permeability
Irritation and essential oils
Skin sensitization and allergy
How to minimize risk
What to do in case of adverse reaction

You will be able to:

  • Distinguish irritation and allergy
  • Identify safe dilutions for specific oils and uses
  • Explain procedure in case of irritation or allergy
Lesson 4 - Phototoxicity, Bath Safety

Bath safety
Safe bath formulations
What is phototoxicity
Risk factors
Safe oils and safe dilutions

You will be able to:

  • Explain why bath safety is a particular safety issue
  • Explain why only some citrus oils are phototoxic
  • Calculate safe essential oil use for a given circumstance
Lesson 5 - Internal Toxicity and Ingestion

The pros and cons of essential oil ingestion
Metabolism, liver impact, neurotoxicity and drug interaction
The ‘French Method’ and what we can learn from it
Relatively safe ways to ingest essential oils

You will be able to:

  • Explain how ingested essential oils interact with the body
  • Discuss the benefits of different excipients for ingestion
  • Identify circumstances in which ingestion is not appropriate
Lesson 6 - Mitigating Cancer Risk

Possible and probable carcinogens in essential oils
Gene mutation and EO constituents
Metabolic activation and DNA repair mechanisms
Determining safe levels

You will be able to:

  • Identify essential oils containing possible or probable carcinogens

  • Calculate safe amounts of these oils

  • Discuss DNA repair mechanisms and antitumoral constituents

Lesson 7 - Pregnancy, Childbirth & Breastfeeding

Some safety myths
Neuroendocrine toxicity
Fetotoxicity and miscarriage
Safety during childbirth
Essential oil transfer from mother to breast milk

You will be able to:

  • Avoid harm to the developing fetus

  • Make sensible essential oil choices during pregnancy

  • Use essential oils safely during childbirth and breastfeeding

Lesson 8 - Practical Safety
  • Calculating amounts and percentages
  • Formulating for safety
  • Bases and shelf life
  • Managing risk factors
  • Making decisions

You will be able to:

  • Demonstrate ability to convert between drops, ml and %
  • Explain how to modify blends containing oils with similar safety issues
  • Distinguish different types of risk factor
learn about essential oil safety from the expert

 When You Complete the Masterclass

CERTIFICATION
Your certificate is signed by Robert Tisserand and issued by the leaders of evidence-based instruction. It demonstrates your knowledge of the safe and effective use of essential oils, and your dedication to the safety of your clients.

THE LITTLE BOOK OF SAFETY
A printable e-book with dilution and safety guidelines, helpful infographics, and tools for risk assessment.

ESSENTIAL OIL SAFETY CHART
A handy reference guide with topical maximums for 100 essential oils, organized by the person’s age and health status.

SINGLE CLASS INCLUDED: OXIDATION & SHELF LIFE OF ESSENTIAL OILS
A single class dedicated to oxidation of essential oils and how to prolong shelf life through proper storage is a part of this course.

What previous students say about this masterclass:

The extraordinary expertise of R. Tisserand in EO. Explanations are clear, based on facts and clinical facts. Wonderful courses. ~ Laure Mattia
Thank you for such a wonderful and informative class! I have learned an abundance of wonderful information to not only help me to help others, but also to be able share my newly attained knowledge to help others better understand EO safety. I’m hoping for more of these in the future as I expand my knowledge of Aromatherapy! Thank you again! Blessings to all! ~ Lisa Macy
I wanted to thank you so much for this class! It was wonderfully organized and I looked forward to it every week. I really appreciate all your efforts to bring essential oil safety awareness to everyone. I am constantly referring to your book in my store and recommend it to all of my students. Thank you, thank you, thank you! I am really looking forward to future classes! ~ Natalie Hajdu-Voakes
I appreciate that the information is video recorded as well as written and that the material is so well organized. I also appreciate that Hana is quick to reply to emails and support us in our learning. ~ Laurie Myers
I enjoyed the way Hana and Robert interact to make sure the material is understood. ~ Debra Gildernew
I want to thank you for this course. I feel so confident having your institute as my education platform. I’m a beginner but with your amazing education, it won’t be long before I’m a pro!
The prompt response to our questions is fantastic. The presentations each week are very educational, they address my concerns about safety, and the overall format is brilliant!
I really enjoyed the course! Hope to take another in the future. Thank you both! ~ Carol Friberg

This is an opportunity to study under the guidance of one of the world’s leading experts on essential oils – don’t miss this chance! Let Robert Tisserand guide you in creating safe and effective blends with parameters based on clinical trials and scientific research.

Ready to get started?

Jump right in!

FAQs

Will there be notes for me to review?
Yes. Each lesson comes with printable handouts of the slides used in the lesson, and additional lesson notes. These are sent to you before each lesson and are for you to keep and refer to at any time.
I am a certified aromatherapist. Will I learn anything new?
Many of our students have commented that our courses helped them grasp what they learned elsewhere in more detail, or complemented their previous education. Some of our students are lifelong learners, and some are teachers.
I am new to essential oils. Is this course for me?
We will let one of our previous students answer this one:

“The information presented is appropriate for all levels, and although I am just beginning my aromatherapy journey it all makes sense.”

Will there be assessments or exams? What kind?

Each weekly lesson is followed by a multiple choice quiz, and there is a summary test at the end of each course. Passing both the weekly quizzes and the final tests is a requirement for certification.

You will be given enough time to prepare for the test as well as three attempts to pass. 

Will I be able to ask questions?

Absolutely! In addition to the live Q&A sessions, you can post your questions in the dedicated student forums where the tutor and the TI team will address them. 

What if I cannot participate on a live session?

All of our live sessions are recorded and are posted on the learning platform within 24 hours so you can watch them, or rewatch as needed during the course. 

How long will I have access to the recordings?

You will have access to all the videos for at least four weeks after the last lesson (see course description for clarification as this changes for individual courses). All the printable materials (notes, handouts, charts, etc.) are of course yours to keep for reference forever.

Do you offer continuing education credits?

Because we have students from all over the world and of many professions we are not able to offer credits for specific organizations – there are simply too many. However, we issue a confirmation of CE hours gained on the course that you can apply with your professional organization and will be happy to assist with any additional documentation.

At the moment, we are an Approved Continuing Education Provider with NAHA. 

What if I fall behind or cannot attend classes?
We have found that running classes on specific dates works best to help you finish a program. You join a class of students, and learn along with them. Many students help each other with queries, and of course our tutors are there too. That said, if you miss a few classes you should be still able to comfortably jump right back in and if you do fall behind you can request extra time. Of course this cannot be indefinite, but we do our best to help you get your certificate.