Advice on the safety issues of using essential oils

Essential oil safety.
The known and the unknown.

By Martin Watt

It is important for you to appreciate that most essential oils can be hazardous
if they are not used correctly.

Most essential oils are perfectly safe for the general public, but there are a few
with well-documented dangers. Regretfully, many essential oils suppliers do
not provide adequate safety information with their oils. There are many around
who will sell anything to make a fast buck!

Most adverse effects resulting from essential oil use are skin reactions rather
than toxicological effects. Toxicity is only of much relevance if someone were
foolish enough to consume certain oils to excess. However, the adverse
effects on the skin should never be underrated
as these can be severe
and long lasting. Oils such as expressed bergamot can cause a lifelong
condition known as photosensitisation. Oils like peppermint and cinnamon bark
can burn the skin if they are in contact for too long. So the lesson to this is
ensure you acquire sound information before using any essential oils, and
never be tempted to use more than advised. Be wary of safety advice in the
popular aromatherapy books and social media, much of this is badly flawed.

For many years a large volume of scientific information has been available on
the safety of essential oils. Many essential oils have been used for over 100
years as ingredients of: medicines; food; drink; perfumes; cosmetics; soaps;
detergents; candles; industrial applications, etc. Due to this widespread use,
various authorities around the world have investigated the safety of essential
oils in most of their common uses.

Sources of information
The World Health Organisation publishes papers on the maximum levels
recommended in foodstuffs. Their deliberations are ongoing and from time to
time new reports are issued.

The Council of Europe has published similar guidelines.

The FDA in the United States has lists of GRAS status ingredients for foods
which include some essential oils. “Generally regarded as safe” only means
when used in the volumes normal for the food trade where only tiny amounts
of oil may be used.

Many countries have their own legislation regulating the most dangerous oils.

How do organisations assess the safety of essential oils?
They have many sources of information to draw on, or if they are uncertain,
they will commission research. Many essential oils were listed in several
National Pharmacopoeias around the turn of the Century because they were
commonly used in medicinal preparations. However, subsequently a significant
amount of scientific investigations have been undertaken, particularly in
universities around the world. Some of this work has been co-ordinated for
regulatory authorities, and some experiments are done just for academic

The best source of safety information of relevance in aromatherapy was the
IFRA (International Fragrance Research Association) and their sister
organisation the RIFM (Research Institute for Fragrance Materials). These
organisations collect data in a number of ways: they gather scientific
information and assess it; member companies report adverse reactions to
fragrance materials to them, and if necessary, IFRA in turn circulate member
companies with warning notices. They have commissioned significant research
evaluations of fragrance materials. For decades these organisations have
published their findings in an extensive series of monographs in the journal
Food and Chemicals Toxicity. Unfortunately, in recent years, these
organisations have been influenced by fragrance chemists who only understand
organic chemistry. Nowadays their safety guidelines are highly suspect over
the use of essential oils. The reason for this is because rather than assessing
side effects by the use of a whole essential oil on humans and animals - which
they did in the not so distant past-, they now make wild guesses based on the
occurrence of a single chemical in an essential oil. That is unreliable as
essential oils contain hundreds of chemicals with interactions that change the
nature and activity of individual chemicals in it. Only tests on the whole oil
should be considered valid.

The fragrance trade organisations did vital work gathering data from adverse
reactions reports and from testing the material in clinics around the world. The
aromatherapy trade is a cottage industry - despite what the public may
think - and it has no co-ordinated system to monitor adverse reactions

to the products they use.

How is testing done?
Testing for toxicity is done on animals or in cell cultures. Most of the testing
was done in the early 1970s. However, animal testing of essential oils and their
components does still happen, mainly in Universities. The toxicity of a few oils
in humans has been documented from past cases of poisoning.

Skin adverse effects
Some of these tests were done on animals, but the final testing was on
humans. These kind of tests are still conducted on volunteer panels of humans.
Specialist dermatology clinics around the world test people they think may be
allergic to fragrance compounds as part of their routine testing procedures.
These results are often published in International dermatology journals and
add to the wealth of knowledge on the side effects of essential oils.
Legal considerations
Before embarking on the known hazards of using essential oils, we should look
at existing law relating to the sale and supply of essential oils.

Under UK and EU law, it is an offence to place any product on the market if
known hazards may be associated with misuse or inappropriate use of the
product. That is unless "appropriate warnings" are attached to the product.
Despite that, many traders still ignore this important piece of consumer
protection legislation.

The European Union (EU) are constantly producing the most idiotic
recommendations and laws on the use of natural botanical extracts. These are
nearly all based around the single chemical principal and are crazy

In the USA there are strict laws over labelling for products that may present a
risk to health. Numerous aromatherapy suppliers in the USA do not comply
with those laws. Also in the USA, numerous home cosmetics and soap
producers are completely ignorant of safety issues.

'Appropriate warnings' is the most important issue. There is nothing wrong
with selling many of our most hazardous oils for non-contact uses, i.e. in
fragrance heaters, pot pourii, candles, etc. However, it is unscrupulous to not
warn people that these products should not be applied to the skin, and also
probably illegal. Expressed bergamot and lime oils are good examples of where
dangers are well documented and therefore the products should have warning

The legal position of anyone that uses oils with known dangers, in a
professional setting, such as in an aromatherapy treatment, requires
examination. If a major trade organisation such as IFRA has advised the large
fragrance companies against the use of such materials for years then anyone
ignoring that would have less of a defense. If someone used such a substance,
and their client suffered a side effect as a result the client would have a
powerful legal case to argue. In such circumstances, a court might deem it
“unreasonable”, for a qualified aromatherapist to use the material in an
'inappropriate manner'. Here I am particularly thinking about oils such as
expressed bergamot, where if used in a health club, before someone goes
under the sun bed, could cause a very severe skin reaction.

It is also highly likely, that if the therapist did this, then their
insurance company would refuse to stand by them and cover any
subsequent damages awarded.

Adverse skin reactions

The 3 main kinds of reactions that can occur from essential oils applied
to the skin are:

This is where a substance comes into contact with the skin, and causes
anything from a mild itch to burns. The important thing is it that once the
substance is removed and healing takes place, there should be no more

Sensitisation - a far more serious situation than irritation:
Once the substance has been introduced to the skin, it can cause permanent
changes in the immune system in a similar manner to a vaccination. On first
use no adverse effects may be seen. However, the body may have been
sensitised, and next time the same or a similar substance is used, a reaction
may occur. The severity can again be just a mild itch, through to the extreme
of severe anaphylactic shock. However, the later in aromatherapy is almost
unknown. Sensitisation in aromatherapy is something to be on constant alert
for. If after using any essential oil or absolute, an irritating or burning
sensation, or a blotchy irritable skin rash are noticed, then that particular oil or
chemically similar ones should not be used again. This type of reaction is far
more likely to occur with therapists rather than their clients.

Photosensitisation (sometimes referred to as phototoxicity):
This is where a substance coming into contact with the skin can react with ultra
violet light. This reaction may cause anything from mild brown blotches
through to severe burning of the skin. The condition can be long lasting and
subsequent exposure of the skin to ultra violet light can trigger a reaction. It is
vital to remember that it is ultra violet light which causes the problem and this
can occur even on relatively dull days. Therefore it is not as many
aromatherapy authors say "caused only by bright sunlight". The main essential
oils to avoid in this respect are expressed Bergamot and Lime. The Bergamot
grade known as FCF is perfectly safe. See other articles on Photosensitisation.
Miscellaneous claimed adverse effects

The vast majority of claims made in aromatherapy books about not using
certain oils during pregnancy are unfounded. Many such claims are based not
on the essential oil concerned, but are from the traditionally claimed effects of
the water soluble herbal extracts when taken internally. Such extracts are
frequently totally different to the same plants oil.

The facts are that most common essential oils are permitted food flavourings.
If there were the slightest evidence that using essential oils externally was
any threat to the health of a foetus, then the oils concerned would have been
restricted by legislation long ago.

If suffering from severe morning sickness early in pregnancy, then the smell of
something like peppermint or spearmint oil may well subdue the nausea. In a
case of constant vomiting the implanted foetus is far more likely to be
dislodged by the traumatic muscular contractions of the uterus, than from the
effects of the inhalation of ANY essential oils.

The birch and wintergreenoilsare best avoided during pregnancy. This is
because indications are that the main chemical may be absorbed by the skin.
High levels of methyl salicylate in the bloodstream are not desirable in

Clary sage is perfectly safe in a normal pregnancy, but should perhaps be
avoided by anyone with a history of early miscarriages.

The main contra-indication of essential oils use during pregnancy is the
heightened chance of causing skin irritation. In late pregnancy the skin can
become very itchy and sometimes inflamed. In such circumstances essential
oils in massage or in the bath might make the condition worse.

There is no sound scientific evidence that any particular essential oils can
trigger an epileptic incident. In fact it is well documented that any powerful
smell can initiate such an attack. Therefore, the only general advice might be
to avoid the pungent oils like camphor, eucalyptus, tea tree, rosemary, etc. On
the other hand, some trials have indicated that the traditionally relaxing oils
can substantially reduce the incidence of attacks. (See more in letter below).

High or low blood pressure
There have been few comprehensive trials published where blood pressure has
been monitored after the external application of oils on humans . There are no
proven cases of anyone who has suffered ill effects from an escalation of blood
pressure caused by aromatherapy. Indeed the opposite is likely, which is that a
nice relaxing massage, or the use of the oils as room fragrance, will decrease a
blood pressure if that is stress related.

The use of little known 'chemotypes' & untested essential oils

The vast majority of our commonest essential oils have been well tried and
tested and safety levels have been ascertained. However, when an
aromatherapist uses oils whose safety has not been adequately ascertained,
they are actually using their clients as human guinea pigs. Unless a client is
told that the safety of such oils is unknown, then this is certainly unethical and
possibly could leave the therapist open to legal challenges if things went

Many of the 'untested' oils are said by some people to have been "used
traditionally". However, when this statement is carefully checked this is often
found in error. The reason is that what has been used traditionally is the herb
not the oil. This is one of the biggest errors in aromatherapy. Herbal
preparations contain totally different chemicals, with often totally different
actions, to those occurring in a distilled oil from the same plant. See 'hyped
oils' article in the archive for more details.

There are some compounds occurring in plant oils that can cause sensitisation
reactions when only occurring at a few parts per million. Therefore, chemical
analysis of the major compounds occurring in the oil can give no guide as to its
safety. This misguided chemistry forms a major part of the teachings of certain
aromatherapy teachers. If it were possible to judge safety by such means, then
large organisations specialising in safety would not need to have spent millions
on safety trials.

In relation to the above, below are some essential oils which you
should be cautious about:

The following list is incomplete because there is a never ending flow of 'new'
oils being pushed into aromatherapy. It is common to find that scientists have
found very good therapeutic properties in some newly discovered plant oil.
These scientists then publish their findings. The next thing is everyone wants
to buy this new magical oil. Few, the scientists concerned included, pause to
give a second thought to the potential side effects of this wonderful new
discovery. Unfortunately, it is not until some individual has been harmed that
someone gives safety a second thought. So the moral of all this is to be safe,
stick to those oils the safety of which has been well documented.

The below refer to essential oils and related extracts, not the herb
Alant Root (Inula helenium)
Never use this on the skin, it is a powerful sensitiser with no known

Almond bitter
The unrectified oil is highly toxic. Rare but you may come across it.

Amni visnaga
No formal safety trials are known.

A well documented sensitiser - IFRA recommend only grades processed to
remove the allergens should be used in consumer products. These grades are
not generally available via aromatherapy suppliers. See the article on 'benzoin'.

Bergamot expressed
This unmodified oil is a powerful photosensitizer, to be safe only use the FCF

Birch sweet and Birch Tar oil
There are many reports in the literature about birch extracts causing
dermatitis. This oil is NOT a natural extract, it is a chemical even if it is
extracted from the bark, most however is 100% synthetic.

Boldo leaf
Very toxic if consumed, so best avoided.

A carcinogen in animal studies, and banned in cosmetics.

A powerful sensitizing agent, reported to cause skin irritation, dermatitis and
acne-type eruptions.

No formal safety trials are known.

Camphor brown, yellow or unrectified only
These unrefined grades may contain high levels of undesirable safrole.

Cassia bark
An extremely powerful irritant and an even worse sensitiser.

Cinnamon bark
An extremely powerful irritant and an even worse sensitiser.

Chamomile moroc
This oil has not undergone any Internationally acceptable safety testing.

Chenopodium (Wormseed)
Is listed as a "prescription-only" medicinal substance in the UK. It is highly

A cause of dermatitis and eczema. Not to be used in cosmetic products.

Copaiba or copahu
Can cause sensitisation reactions if it is old and oxidised.
Costus root
It is a powerful sensitiser and should never be used on the skin.

Fennel bitter
Not widely available, but old samples of the oil have induced sensitization.

Eucalyptus chemotypes
Few of the available “chemotypes” have been tested. E. globulus types and
Eucalyptus citriodora have been.

Fig leaf absolute
This is a powerful sensitiser with no known antidote. Most sold as such is
a perfume compound.

A powerful vesicant which will burn the skin.

Inula graveolens
A related species Inula helenium root oil, is one of the most hazardous
essential oils available. Therefore, until such time as formal testing has been
done, it is unwise to use this oil on the skin.

Lemon expressed
Can be a photosensitiser given the right circumstances-See article 'Factors
Affecting Photosensitisation'.

Lime expressed
A powerful photosensitiser which is best avoided for skin application,
distilled is far safer. Avoid rubbing the peel on the skin.

This oil has not undergone safety testing published in the accepted journals.

This oil has not undergone safety testing published in the accepted journals.

Mustard volatile
A powerful vesicant which will burn the skin.

The pure oil has not undergone Internationally acceptable safety testing.

Ocotea - O. cymbarum
It can contain up to 93% safrole bringing it under the same legislation as
genuine sassafras oil which is banned in cosmetic products in Europe.

A suspect sensitiser and cross reactions to similar oils are recorded.

Peru balsam
A powerful sensitiser. IFRA recommend "not to be used as a fragrance
ingredient". The oil may be safer than the balsam, but those reacting to similar
chemicals may still cross react.

Ravensara aromatica and similar names
None of the oils bearing the Ravensara name have undergone any formal
safety trials.

Rosemary chemotypes
Only the common cineol types have been tested.

Rue oil
A terrible photosensitiser and sensitiser.

This oil is restricted to such low levels in cosmetic products throughout Europe,
that it effectively bans its use. Tests have shown it is possibly carcinogenic.

These oils have not undergone Internationally acceptable safety testing.

A powerful photosensitiser. Therefore, to use it on skin exposed to the light
would be foolish.

Tansy oil (T. vulgaris)
Extremely toxic. All other oils sold as "Tansy or Tansy blue" are untested for
skin safety.

Tolu balsam
If someone has become sensitive to other fragrance ingredients, they may

Turpentine unrectified
This is rare to find now, but it is a known sensitising agent.

Thyme chemotypes
Only the common phenol types have been tested.

An extremely powerful sensitiser - Do not use it on the skin.

See birch above, also this chemical oil is highly toxic and can be absorbed by
the skin. Never ever use it during pregnancy.

Used in aromatherapy but this oil has not undergone formal safety tests.

If anyone sees oils on open sale without appropriate warnings, you should tell
the vendor that the safety is unknown. Often they may not know, and may
have relied for their knowledge entirely on the popular aromatherapy novels,
on some of the appallingly poor training courses around, or con artist oil

Banned or restricted oils

The only essential oils that are prohibited for resale to the public under the UK
1968 Medicines Act are: Chenepodium (American wormseed), savin oil and
croton oil. These oils may only be distributed to the medical profession from
licensed pharmaceutical premises.

Another oil that is 'effectively' banned in cosmetic products is Sassafras oil. By
'effectively' banned this is because the E.U. only permit safrol in products at
below at 100 ppm. Since raw Sassafras oil contains about 870,000 p.p.m. of
safrole, this means that in aromatherapy you would have great difficulty in
diluting the oil to a safe and legal level of use.

Countries within the European Community vary considerably in which essential
oils can or can't be sold, and how they may be used. However, once the oil is
introduced to a product formulation, the laws are almost standardised now.
Other issues affecting safety.
Sell by, or use by dates
This is an important piece of safety information to take note of. Certain
essential oils, particularly those of the citrus and pine families, develop skin
sensitising chemicals as they age. Without analysis one cannot be certain how
quickly the oils have aged. Therefore, as a general rule, I advise people not to
use such oils on the skin after about 6 months of storage. They can of
course still be used for room fragrance purposes. Storing such oils in optimum
conditions, such as in sealed containers in a refrigerator will slow down the
chemical changes in the oil. It now seems lavender or oils high in linalool may
also be a cause of this problem. See article Old Lavender oil.
Epilepsy and the hype
Some compilations of my posts to old IDMA aromatherapy group about
the widely held belief that people suffering from Epilepsy should not
be exposed to Rosemary oil.

My comments were based on Dr Betts own acknowledgement of how powerful
auto suggestion is, and the fact that maybe years before, this patient may
have read that rosemary was contra indicated in epilepsy. This would have
been sufficient for a subsequent exposure to cause the recorded increase in
brain wave patterns.

I am aware of all the other papers that Gabriel & Bob Harris quote. They are a
ragbag of stupid experiments on rats where the volumes of chemicals they are
exposed to are way above anything that would ever be used in aromatherapy,
or prolonged inhalation in humans. They are also based on the internal
consumption of chemicals such as synthetic camphor (no, not the same as

Statements attributed to the Dutch herbalist such as "Large doses of rosemary
have been shown to cause convulsions in patients", are meaningless unless the
dose is provided and a valid checkable reference.

From Dr. Betts new reply to Gabriel, the following very interesting note: "there
is also the possible effect of a conditioned response to the smell....
apprehension about using a 'dangerous' oil might also be enough to trigger off
a seizure".

Yes indeed, and who is responsible for such effects - unjustified statements
made by aromatherapy authors!

I would agree with being cautious about advocating the use of any harsh
smelling product for use by an epileptic person. However, a good quality hydro
distilled rosemary oil is not harsh smelling, it smells like the plant which can
have a wonderful fragrance, nothing at all like camphor. However, in
aromatherapy there are steam-distilled oils that do smell very camphoraceous.

Rosemary oil is a GRAS status permitted food flavouring used in alcoholic and
non alcoholic beverages, frozen deserts, candy, baked goods, meat products,
relishes, etc. at a maximum use level of 26 ppm and does anyone tell an
epileptic person not to have rosemary with their lamb?

We have already discussed on this list how little essential oil gets into the body
during an average aromatherapy treatment. Of course if someone sits sniffing
at a bottle they may well get a lot of camphor and the other chemicals in their
bloodstream but that is not what happens with an average treatment.

I stick by what I said earlier, which is that there is not a shed of sound
evidence that rosemary can initiate an epileptic incident any more than
numerous other smells.

From a group posting
Pat said: "I am convinced that there is at least the possibility that Rosemary
Essential Oil may cause seizures".

ME: So on what basis are you "convinced"? I can see no ethical problem, if
there is no good basis for your conviction that rosemary oil can cause the
suggested effects.

As to if I would do a trial on epileptic patients using rosemary. Yes, but only if
they were first de programmed from possible previous auto suggestion that
'rosemary may be a danger'. A good clinical hypnotherapist could do that.

I hate giving anecdotal cases, but this may be of relevance. I had a student in
Florida who told me that rosemary oil was the only thing that prevented a
seizure in her husband. He had brain damage following a car smash that left
him subject to fitting and the drugs he was given did not help.

He had just a sniff from a bottle (as he felt the aura coming on) and it stopped
the fit. I guess this is not the same as those people born with epilepsy, but this
is an example of the need not to dismiss a 'potential' treatment using an
otherwise perfectly safe product.

In the 1700s Rosemary oil was given internally by doctors to control

As to the case of the dog; well tea tree oil has been reported to have the same
effect on dogs. Do we therefore include tea tree in the oils not to be used by

In fact I have got several of the references that Bob Harris mentioned. You see
I do something most people don't bother about, which is obtain the *whole*
research paper rather than just the extracts. When you get the whole papers a
very different picture can emerge compared to just reading the abstract. For
example, it is extremely common to find experiments on animals where
synthetic fragrance chemicals are used. These chemicals are rarely identical to
the equivalent natural one. This may not invalidate results, but does raise huge
questions on the accuracy of results obtained.

My comments on the use of rosemary in food are perfectly valid on this issue.
This is because several of the experiments on animals have been from the
internal administration of the essential oil. In addition, the suggestion is that it
is the smell of rosemary that can cause a problem, in which case even cooking
with the herb creates a strong smell of rosemary.

There are several errors in the suggestions that inhaled camphor or 1,8-cineole
might cause seizures when used as part of an average aromatherapy
treatment. Also in the theory of first liver bypass via skin absorption. In a
massage the volume of chemicals entering the body is minute. The question of
skin absorption should by now be a dead duck. It is not, simply because most
aromatherapy teachers do not want to face the truth, which is they have been
teaching nonsense for years. The clear evidence is that is *not* a pathway by
which pharmacological volumes of oil get into the body. See the article on 'Skin

From the research I have got, it would appear reasonably large amounts of
certain chemicals in essential oils can get into the bloodstream via inhalation.
However, during the average aromatherapy massage, particularly with oils like
rosemary, only a few drops are applied all over the body. The person *doing*
the massage will get far more vapours in their body than the person being
This is primarily because hot gases rise, (another basic piece of
science that most aromatherapy teachers ignore). Therefore, the volume of the
chemicals getting into the body of the 'client' would be considered by a
pharmacologist as of little or no significance.

Yes, of course I agree with you about people using the oil in excess could
cause problems. I also believe you may be correct in informing people with a
history of seizures about the controversy over rosemary oil. They of course
have a right to know. However, in honesty, it should be put to them that the
matter is 'not settled', rather than put to them that that they "might get a

Finally, I still cannot see any reason why we should implicate rosemary rather
than many other oils, as being contra indicated for epileptic people. You should
also consider how well known I am for promoting the safe use of essential oils.
If I have the slightest suspicion that something is dangerous then I tell people
about it. This thing over rosemary is just a part of the unjustified hype and
urban myths that our trade is riddled with.

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