PharmacoTherapeutics of Essential Oils

This two-course program will take you inside the human body and show you the principles of aromatic pharmacology – from how essential oil constituents move in our body to how our body reacts to them. Future-proof your practice through a deep understanding of how aromatherapy works on a cellular level.

Includes: Essential Oil Kinetics Masterclass and PharmacoDynamics Masterclass

Essential Oil Kinetics Masterclass (Part 1)

What happens after an essential oil comes in contact with your body? While it’s true that specific oils have certain properties, choosing the right oil or blend for an ailment is only a part of the solution. Where do you apply? In what dose or dilution? How frequently and for how long? The pathways that essential oils take in the body, and their mechanisms, can greatly influence therapeutic efficacy. A six-lesson course on how essential oil constituents travel through the body, with focus on each of the modes of application (inhalation, topical, ingestion)

Completion of this course is a prerequisite for Part 2.

PharmacoDynamics Masterclass (Part 2)

As the next step on your journey to understand the pharmacological effects of essential oils, this course, and Dr Petra Ratajc, will take a close look at the major essential oil therapeutic effects – antimicrobial, antioxidant, anti-inflammatory, analgesic – and help you understand the underlying mechanisms. She will also guide you through the basic principles of pharmacology, and help you understand the issues of potency and efficacy.  

What You Get in the Program

Part 1: Six 60-minute LIVE lessons.
Part 2: Six 60-minute LIVE lessons.

Part 1: Six LIVE Q&A sessions
Part 2: Six LIVE Q&A sessions

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

Access to our private online forum to ask questions and interact with Petra, the TI team, and classmates. 

Ongoing access to the learning platform for six months after course completion.

Petra Ratajc, PhD

Biologist | Researcher | Educator

On her myth-busting plant biology blog, The PhytoVolatilome, Petra refers to herself as an aromatic plants enthusiast. But click through to just one of her posts, and it’s obvious that she’s so much more than that – and backed by some serious credentials.

Petra Ratajc has a post-graduate degree in Biological and Biotechnical Sciences from the University of Ljubljana. Her PhD extends from fieldwork to molecular research in the quality, safety and efficacy of aromatic herbs and their essential oils. Petra specializes in medicinal and aromatic plants, secondary plant metabolites, pharmacognosy and pharmacology – specifically focused on plant volatile constituents.

Besides bringing an unequivocal depth of knowledge to this course, Petra is an experienced lecturer and presenter at various seminars and workshops.

Course Breakdown



Lesson 1 - Human Body Networks and Pathways
  • The structure of the body, and how it processes nutrients and foreign molecules
  • Comparing single substance medicines and natural complex medicines
  • How essential oil constituents are absorbed, distributed, metabolized, and eliminated
  • The difference between pharmacological and psychological mechanisms
Lesson 2 - Inhalation & the Olfactory System
  • The olfactory system and the brain
  • Olfactory receptors and the sense of smell: pathways, mechanisms, anosmias
  • How essential oils influence the body and mind via the olfactory system
  • The psychological effects of odor; hedonics, semantics, expectation
Lesson 3 - Inhalation & the Respiratory System
  • The respiratory system, and what happens when we inhale essential oils
  • How compounds transfer from the air to the lungs to the bloodstream
  • The blood-brain barrier and the “nose-to-brain” route
  • When and how to use respiratory inhalation as a therapeutic method
Lesson 4 - Topical Application & Effects
  • The structure of the skin, and factors that influence permeability
  • Penetration pathways, penetration enhancers, and how much is absorbed
  • Blending essential oils for optimal absorption
  • Safety issues, and when to apply essential oils topically as a therapeutic method
Lesson 5 - Ingestion & the Internal Debate
  • The digestive system, and the route essential oils take after ingestion
  • Liver metabolism and the bioavailabity of essential oil constituents
  • Using essential oils for flavor compared to therapeutic doses and effects
  • Determining when the ingestion of essential oils is appropriate
Lesson 6 - Practical Application Guidelines
  • Calculating and measuring appropriate doses and dilutions
  • How essential oil blending affects calculations of efficacy and safety
  • The therapeutic window, cumulative dosing, and at-risk groups
  • Deciding on appropriate modes of application, delivery systems, and protocols


Lesson 1 - Introduction
  • Human cell and cell signalling
  • Internal targets: receptors, enzymes, transcription factors etc. 
  • Pharmacology definitions and principles
  • Introduction to basic concepts such as drug-receptor interactions and dose-response relationship
Lesson 2 - Antimicrobial activity
  • Microbes and microbial infections
  • Antimicrobial action of essential oils
  • Mechanisms of action
  • How do we know what we know: types of research and its relevance
Lesson 3 - Antioxidant activity
  • Oxidative stress: causes and consquences
  • Internal and external oxidants
  • Health issues where oxidation plays an important role
  • How we know what we know: testing antioxidant potentioal 
Lesson 4 - Inflammation and anti-inflammatory activity
  • Understanding inflammation
  • Essential oils with known anti-inflammatory activity
  • Mechanisms of anti-inflammatory action
  • Typical inflammatory diseases and essential oil treatment
  • How we know what we know: models of studying inflammation
Lesson 5 - Pain
  • Understanding pain
  • Essential oils with analgesic properties
  • Mechanisms of action and examples
  • How do we know what we know: models of studying analgesic activity 
Lesson 6 - Neurological and immunological modulation
  • Essential oils impacting our neurotransmitters
  • Essential oils impacting our immune system
  • How we know what we know
  • Summary of what we learned in the course

What previous students say about our courses:

I would just like to thank Robert and Hana for making EO training available to all. ~ Jo Tyrer
Great support throughout the course, excellent teachers. ~ Nadine
Extremely informative and well presented. Would love to take more classes from you. ~ Petie Maguire
I liked the way the courses built on each other – safety and healthy skin. I appreciated the way Robert was able to make the science understandable and interesting.
Learned SO MUCH about skin and essential oils. Robert Tisserand is not only an expert, a researcher, but also a superb, enthusiastic teacher! ~ Karen

When You Complete the Course

A signed Certificate of Completion issued by the Tisserand Institute for each course.

From your course materials to extra reading on anatomy, physiology and essential oils, you’ll leave with a rich library to go back to whenever you need a refresher. 

The program will empower you with thorough, evidence-based chemistry information.

PharmacoTherapeutics of Essential Oils Certification

Your certificates demonstrate your ability to make informed on using essential oils and the knowledge needed to to use essential oils in accordance with current research. 

Don’t miss your chance to uncover the science behind ‘how’ essential oils work, and make more accurate therapeutic choices.

Ready to get started?


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.