The status quo, the widely believed “wisdom” of the day, is always difficult to change, however illogical or wrong it may be. Blood letting had been widely used for 1,500 years before physicians figured out that it was not, after all, the ideal go-to therapy for all ills. In that context, 36 years is not a long time, but that’s how long the aromatherapy community has been under the illusion that oils of rosemary, hyssop, sage and thyme should not be used for people with high blood pressure.
In 1964, Dr Jean Valnet’s book Aromathérapie was published. It was a hugely important publication in the development of aromatherapy, and it had a tremendous impact on my own aromatherapy career. However, the quantity and quality of essential oil research available in the early 1960s was extremely poor. There simply wasn’t very much to go on.
In his book, Valnet lists the above four essential oils as “hypertenseur”, and for each one he gives two references: Caujolle, and Cazal. However, the 1944 Caujolle paper he cites is actually about essential oils of lavender, lavandin and spike lavender, all of which were reported to produce a brief reduction in blood pressure after intravenous injection into dogs. None of the other four oils are mentioned, so clearly, this reference was a mistake.
Caujolle and Franck published two other papers, both in 1945, that Valnet might have in fact be referring to. One was about hyssop oil. Injected iv into dogs, it caused an initial drop in blood pressure and then (since the dose was high enough to induce seizures) blood pressure suddenly increased as the seizures came on, and decreased again when they subsided. This spike in blood pressure was considered to be a consequence of the muscular contractions related to the seizures. Unless used in convulsant doses, hyssop oil is in fact hypotensive. The other paper was about clary sage oil, not sage oil. Injected iv into dogs, it caused a slight increase in blood pressure. This paper also noted that sage oil usually caused blood pressure to reduce. The other reference given by Valnet (Cazal) was a thesis from 1943, which I have not been able to find.
Dr Jean Valnet
Valnet’s contraindication in Aromathérapie is under “usage interne” – internal use – but he does not give a contraindication for “usage externe”. So, even according to Valnet, massage with any of these four oils would NOT be contraindicated in high blood pressure.
In spite of all of the above, Valnet’s advice has been (a) assumed to apply to all uses of these four oils, and (b) repeated in almost all aromatherapy texts since, at least the ones that give safety advice for hypertension. And other oils have been added to the list over time. However, if you look at the research the surprising conclusion is that there is no evidence that any of the contraindicated essential oils – whether listed by Valnet or anyone else – raises blood pressure. In fact most of them reduce it.
In: Essential Oils and Hypertension – is There a Problem? I explain why I believe that there is no case for contraindicating any essential oil in someone with high blood pressure. As well as closely examining the evidence above, I also refer to more recent research, which confirms that the four “Valnet oils” present no risk. The lack of compelling evidence is reason enough to let go of this chimera. There’s also the fact that aromatherapists have plenty of legal challenges to deal with already, and it makes no sense to add to this burden by coming up with restrictions that are scientifically unsound, and that are based on a mistake made in a book in 1964.
Dear Robert,
Thanks for the info about the above 4 oils and their lack of contribution to hypersensitivity. I have used Rosemary on people with many blood pressure conditions with positive ressults.
Best,
Elizabeth
I wonder if the EOs are ADAPTOGENIC; i.e. they lift you up if you need uplifting and calm you down if you need relaxing. I found that to be the case with my patients when it comes to peppermint, which is normally considered an uplifting scent (for some it is relaxing). Can it be that the oils would relax someone with high BP, and uplift people with low BP? Of course, one should always consult with a trained health professional when undergoing EO therapy. Where there is potential for healing, there’s also potential for harm.
I have not seen any hard evidence of adaptogenic action with essential oils, though it’s certainly feasible. But also, we need to be careful how we apply general terms such as “stimulating”. The evidence shows that peppermint oil both increases alertness, and reduces blood pressure. This is not adaptogenesis, nor is it a contradiction, it’s simply that alertness and blood pressure are controlled by different parts of our nervous system, and the same essential oil can be both “stimulating” and “depressing” at the same time, but to different receptor sites or neurochemical pathways.
As synchronicity would have it, I was examining the latest research and updating the “Safe and Smart” advice on my website. This paragraph:
“High or Low Blood Pressure: There are no scientifically verified trials published, following the external application of essential oils. There are also no proven cases of anyone that has suffered ill effects from escalation of blood pressure caused by aromatherapy. Generally, an aromatherapy massage will decrease blood pressure that is high due to stress.” will remain intact.
Thanks Robert. I’ve also been disturbed about the plethora of misinformation on the web and will tackle a similar attempt to dispute some of it in my own blog and web pages. Eventually, we can only hope this misinformation will be so dilute as to have no influence.
Once again, thank you for enlightening us. I really enjoy the “Fact or Crap?” information you consistently share in your blog and articles!
As ever, very interesting! I’d be interested if Elizabeth Jones could clarify her comment. I assume hypersensitivity was a typo and should read hypertension? What kind of blood pressure conditions does she mean (hypo or hyper) and what does she mean by “positive” results – an increase, a decrease or no change in blood pressure? And how does she know?! Elizabeth, I’m just trying to understand this – am not saying you’re wrong, it’s just not clear what you mean.
Dear Robert. Thank you for this article. It is indeed unlikely that EO of Thyme increases blood pressure. I have used this EO externally for calcifications, such as bone spurs. I was taught it had properties of lysis in this instance. If it has those properties would it not also be beneficial for atherosclerosis?
Just my two cents!
greetings
Andrea
Andrea, thank you for your comment. Lysis means the breaking down (rupturing) of a cell. Thyme oil can have this effect on bacteria, but there’s no evidence that it breaks down bone cells. In fact thymol, the main constituent of most thyme oils, has the opposite effect, strengthening bone by inhibiting the process that breaks down bone cells. Good in osteoporosis.
Atherosclerosis – hardening of arteries – I’m not aware of any research suggesting that thyme oil would be helpful.
Dear Robert,
Could you please clarify whether Cypress essential oil is safe postnatally with women who are taking hypotensive medication as the textbooks mention it as a hypertensive essential oil?
Thank you,
Ingrid
Ingrid – there is certainly no evidence that cypress essential oil raises blood pressure. Nor is there any reason to suspect that it might, in my opinion.
Dear Robert,
How are you? Glad to access your website and happy to see the distinguished aromatherapists that visit and contribute to it! First, we have to start referring to oils in terms of their chemotypes (as well as other variables). Just using the generic term “rosemary” or “thyme” can be misleading and spread misinformation. I am saddened by experiments done on dogs with iv injections of essential oils – it goes counter to what we stand for as holistic aromatherapists. By now, since you came out with “The Art of Aromatherapy” we, aromatherapists all over the world have amassed enough experience to know how oils interact with human physiology – it would be nice if someone would come forth to compile a compendium of such information. In my experience most Rosemary chemotypes except for Rosemary verbenone do increase blood pressure as do oils from the cinnamon family and quite a few other known “stimulating” oils. Often the elevation is only temporary but those with high bp should use discernment and increased dilution.
Hi Naomie, and thank you for your contribution. I have given chemotypes when they are mentioned – which is rarely! But we can safely assume that the thyme referred to by Valnet, and used on dogs etc, is the thymol chemotype. This was mostly in the 1940s, and would not be ethical now, at least not in the West.
I’m interested only in evidence – do you have any?