What is Camphor?
Camphor essential oil is steam distilled from the wood of camphor tree. The defining fragrance of Chinese Camphor, is in fact, native to Japan, where the tree is known as Hon sho.
Mother nature in her majesty has created several different chemotypes around the world, all considered to be sub-species of Hon sho, but having very different chemistries, and thus actions between them.
In his 1950 book The Essential Oils Vol. IV, Ernest Guenther tells us that:
There are three morphologically identical, but physiologically different varieties of the camphor tree (Cinnamomum camphora Sieb).
1. Hon-Sho, the true camphor tree, occurring chiefly in Formosa and Japan, and yielding an oil which contains 50 and more percent of camphor.
2. Yu-Sho, the camphor oil tree, occurring chiefly in China, and yielding an oil which contains cineole and terpineol as principle constituents, and only 30 - 40 percent camphor.
3. Ho-Sho, the fragrant camphor tree, occurring chiefly in Formosa, and yielding an oil which contains linalool as the principle constituent, and only 30 - 40 percent camphor. 
Camphor wood carries enormous cultural significance in China. The rich yellow-brown wood carves well and polishes up to a gloriously rich mahogany hue.
Historically, furniture makers made elaborate chests from it, enjoying the pungent fresh scent emitted from their creations that also repel insects, bugs, and moths.
This ability to be made into beautiful things naturally led camphor to become the chosen material of the Buddhist temple builder as he carved thousands of exquisite filigrees and lattice work from camphor.
In "The History of Fragrance from Cleopatra to Chanel," Edwin Morris describes how it became fashionable to create covered walkways of camphorwood to invoke deeply meditative states, and glorious statues of Buddha were created from the beautiful wood. 
There are three things you must know about camphor.
1. Camphor is a tree, an essential oil, and chemical constituent
It is a tree, an essential oil, and the chemical constituent which can make up as much as 50% of the essential oil, depending on where it grew.
Five different chemotypes of the oil are commercially available borneol, nerolidol, camphor, 1-8 cineole and linalool. The last three of these are all made into popular essential oils. 
The linalool chemotype, the Japanese call Ho Sho is distilled into Ho Wood. The cineole chemotype, Yu sho is called ravintsara - not to be confused with ravensara aromatica, a different oil.
Where camphor oil is extracted from wood, oil distilled from the leaves is known as Ho-Leaf oil. Ho Wood and Ho Leaf oils are often used by compassionate therapists as a more sustainable substitute for the endangered rosewood oil (Aniba rosaeodora).
2. Camphor essential oil is fractionated.
The chemical constituent camphor turns crystalline and must be filtered off. The extent of the filtration will dictate whether it can be used as a therapeutic in aromatherapy.
- Lightly filtrated - White camphor Oil
- Moderately filtrated - Brown and yellow camphor oil
- Heavily filtrated - Blue camphor oil.
So, if someone asks: "is camphor safe?" the answer is yes, if it is white camphor essential oil.
3. Only white camphor essential oil is used in aromatherapy.
Yellow camphor is high in a chemical constituent, safrole, that may be carcinogenic. Blue and Brown camphor oils are both extremely toxic. 
Since filtration has taken place, the oil is incomplete and strictly speaking, camphor oil isn't an essential oil at all.
We use it in an identical way to as if it were.
Properties of White Camphor Essential Oil
- odontalgic (toothache)
- rubefacient (Causing redness of the skin as it increases circulation to the area)
- stimulant. 
Camphor Essential Oil Uses
Below is a thorough list of its best known uses and examples of blends using white camphor.
Camphorated oil (that is any product with camphor oil added to it) has been used for millennia in traditional medicines to treat toothache and to fight infection in general. 
Since camphor oil is toxic when ingested, we don't want to put it into the mouth. Create a weak topical treatment to rub onto the face, along the jaw.
The oil will absorb through the skin into the blood stream.
In the following blend, we increase camphor's toothache pain killing ability by blending with the other aromatic superpower clove to ease the pain and misery with some gentle healing from spikenard and yarrow.
- 1 tbsp Borage Carrier Oil - Borago officinalis
- 1 drop camphor essential oil - Cinnamomum camphora
- 1 drop clove essential oil - Syzygium aromaticum
- 1 drop yarrow essential oil - Achillea millefolium
- 1 drop spikenard essential oil - Nardostachys jatamansi
Safety: Not suitable for use during the first 16 weeks of pregnancy or while breastfeeding.
Aches and Pains
Edward Weiss, in his 1997 book "Essential Oil Crops" reveals that the German Benedictine Abbess Hildegard von Bingen (1098-1179 AD) referred to the wood as Ganphora (very similar to the Latin name).
Aromatherapists still exploit this counter-irritant mild analgesic action to relieve neuralgia, sciatica, pain, stiffness and similar conditions today.
Science demonstrates this counter-irritant action is executed by a fascinating set of channels that run through our cells. The TRPV (Transient Receptor Potential Vanilloid) have two main actions that we know of.
They work with our sensations of heat and cold, and also our perceptions of pain, especially in hyperalgesic conditions such as fibromyalgia.
Camphor activates TRPV3, exciting the nerves, but if it is used too regularly can lead to a desensitization of these channels. 
What was previously analgesic, no longer helps alleviate the pain. Likewise, it is the TRPV1 channels that counter-irritate the skin to calm itchy or twitchy sensations of allergy reactions.
Blend for Rheumatism and Arthritis
Use this blend when pain is particularly severe.
- 1 tbsp Tamanu Carrier oil - Calophyllum inophyllum
- 1 drop Lavender essential oil - Lavandula angustifolia
- 1 drop juniper essential oil - Juniperus communis
- 1 drop camphor essential oil - Cinnamomum camphora
Good therapy would be to rotate camphor with a drop of ginger in the next blend, and a drop of black pepper in the third. Rotate daily to warm and invigorate the joints.
Safety: Not suitable for the first 16 weeks of pregnancy or while breastfeeding.
Head Cold and Stuffy Nose
Interestingly, these TRPV actions seem to betray a strange property of the oil
Camphor oil does not actually break through nasal congestion. It only seems to feel like it does.
Working similarly to eucalyptus and the menthol, it activates cold receptors in the nose, making it feel as if cold air is pushing through. Oddly though, there hasn't actually been any change to the resistance in the nose. 
Certainly, camphor's effects of making you feel better when you have a cold are important, but they can be improved by adding oils that really do decongest like eucalyptus and frankincense; essential oils that will open the airways too.
Camphor oil also has an antitussive action, that helps to calm spluttery coughs. As a mild expectorant, it will also remove catarrh.  Again, eucalyptus and frankincense will greatly enhance its action, as will monarda essential oil.
Traditional medicine promotes inhalation as the best way to use camphor oil to treat lung complaints.
Inhalation to alleviate symptoms of coughs and colds.
Add essential oils to a large bowl of hot water. Place the head about six inches away from the water to guard against scalding in the steam.
Place a bath towel over, to make a tent and trap the steam. Come out of the steam to take a breather and blow your nose.
This blend uses myrrh, which is a sledgehammer that can cut through any nasal gunk, but it does it quickly.
For this reason, do not use it as the last thing at night or you will be streaming rather than going to sleep. At bedtime, replace myrrh with frankincense.
- 1 drop camphor essential oil - Cinnamomum camphora
- 1 drop monarda essential oil- Monarda fistulosa
- 1 drop myrrh essential oil - Commiphora myrrha
Camphor Essential Oil Benefits and Dangers
White camphor essential oil's main effects on physical health are to the upper respiratory system - especially using inhalation, and to muscular, skeletal, and circulatory tissues used topically.
In aromatherapy, all illness is recognized as a dis-ease between the mind, the body, and the spirit. So attending to the physical body is seen as nothing more than applying a sticking plaster.
Holistic healing must take place on three levels, taking into consideration emotional and mental conflicts too.
Camphor's keyword is "penetrating" and we can relate that not only to cold wind that blows through the sinuses but also penetrated through logical thoughts to rumination of the subconscious.
Considered one of the seven substances sacred to Buddha, a solitary drop on a handkerchief can be used as a tool to aid meditation toward enlightenment.
It's very strange how, when you breathe in camphor, it seems to touch a place inside your head, that no other oil seems to touch.
Deborah Eidsen, author of Vibrational Healing: Revealing the Essence of Nature Through Aromatherapy, explains how camphor seems to unlock the subconscious, allowing us to accept messages from the unconscious into the physical body. 
A drop on the pillow at night, will not only make it feel easier to breathe, but it may help dreams speak from the subconscious more lucidly.
The mental body often creates patterns of response through rigid associations to past traumas and upsets. One of the most usual manifestations of this is through migraine headaches.
Adding camphor oil to blends connects the heart energy to spirit, enhancing the healing properties of other oils and allowing negative energies to simply melt away, removing pains such as tension headaches. 
Lastly, camphor is a specific for shock and hysteria. Peculiarly, we say "scared out of our skin" and camphor acts like a cord pulling the scattered etheric bodies back into the body. In this way, camphor works wonderfully with the grounding effects of vetiver and the soothing majesty of spikenard to anchor the calming energy down.
Camphor Side Effects
Essential oils do not have side effects, only many main effects. This is what makes them both marvelous and treacherous all at the same time.
One of camphor's effects is it is a heart stimulant. The reasons to use this would be few, but it is worth recognizing that people with pacemakers or heart conditions may feel a little strange using this oil. It might best be avoided by these groups.
Camphor is a safe oil when used in small amounts, and not used too often.
Excessive use cancels out its analgesic effects, and can, in very large amounts, cause convulsions, especially in children. 
Safety and contraindications of Camphor Essential Oil
Yellow Camphor has high levels of the chemical constituent safrole which is possibly carcinogenic and should only be used in less than 0.05% (International Fragrance Association).
Tisserand and Young are slightly less cautious suggesting a maximum dilution of 0.25%. 
Do not use camphor essential oil during the first 16 weeks of pregnancy or during breastfeeding. Traditional medicine suggests it may reduce lactation, but also the taste is probably rather off putting to delicate new mouths. 
Since camphor oil is high in limonene and pinene, these are subject to high levels of oxidation. 
Oils high in monoterpenes decay quickly and can lead to skin sensitisation. If you use camphor, you should replace bottles of camphor oil every six months.
It should not be used topically after that period, but it can still be used safely (if not so efficaciously) as an inhalant for aromatherapy.
The chemical constituent Camphor has been found to cause liver injury if taken orally. 
Do not ingest.
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Camphor Essential Oil Research, Facts, and Studies
Strangely, the scientists in the laboratories are not as interested in camphor as they are with other oils like tea tree, for example.
Excitingly for us, the research is mainly based around understanding how the actions traditional medicines use take place.
Camphor's Effects on Sex
Camphor's clinical penetrating aroma may not be your first choice as an aphrodisiac but a fascinating facet of camphor is how various cultures have different associations with its actions on sex.
Voodoo rituals include camphor as a means of enhancing love and attraction, whereas Iranian traditional medicine maintains it has the capacity to both excite and inhibit sexual interest.
Not surprisingly, this intrigued Iranian researcher set rats to work to try to uncover the truth.
56 rats were divided into three equal sized groups. One set of rats were injected intraperitoneally with camphor.
No changes in the levels of testosterone were found and the rats continued to mount each other as they had before. 
So far...the jury's out.
Possibly one of the most important findings about Camphor oil, was found in 2015, when researchers wanted to investigate various oils that may be of help against virulent strains of bacteria.
Camphor inhibited the growth rate of several extremely dangerous pathogens:
Staphylococcus aureus, imipenem-resistant Pseudomonas aeruginosa, multidrug resistant Salmonella typhi, and S. typhimurium in a petri dish. 
Its strongest results were seen against the incredibly nasty Streptococcus pyogenes. 
This gram-positive bacteria is an infrequent visitor to skin microbiota, manifesting in all manner of illnesses from strep throat, impetigo and cellulitis.
It is passed from person to person through a variety of transports such as:
- Respiratory droplets
- Hand contact with nasal discharge and skin contact with impetigo lesions
- Can be carried naturally in the anus, skin, pharynx or vagina
- Contaminated raw eggs or milk
S. pyogenes penetrates host tissues, evades the immune response, and then spreads by penetrating through host tissue layers. 
It may also manifest several weeks after the initial infection of a cold, manifesting in auto-immune illnesses such as such as rheumatic fever.
Camphor then, may be effective against Erysipelas, a strawberry rash that invades the acute layers of the dermis and lymphatic tissue. The lesions of the rash have sharply demarcated edges; the orange peel texture of the rash becomes very red, swollen and warm.
If the rash wasn't enough, the poor patient suffers fevers, shaking, chills, fatigue, headaches and vomiting.
Cellulitis too may respond well to camphor oil, as the red swollen, deeper tissues and sometimes the lymphatic tissues become invaded by the S. pyogenes bacteria.
Prognosis of untreated cellulitis and erysipelas is poor as they can lead to necrotising fasciitis.
Historically, we have seen beautiful furniture being made of camphor to exploit its insecticidal powers. More recently, it has been discovered camphor may be the protector of rose gardens and Christmas cakes!
Trials have shown camphor to be strong fumigant insecticidal properties against Tribolium castaneum (the red flour beetle) and Lasioderma serricorne (the cigarette/ tobacco beetle) which loves to feast on precious dried fruits. 
Spider mites too, were originally native to Eurasia but is now very damaging to crops across the planet, particularly in Hawaii.
This tiny varmint munches on strawberries, tomatoes and other delicious crops in the greenhouse. 
This means war!
In the laboratory mites showed signs of poisoning using both the active constituents in the oil.
Camphor oil is one of the big guns. The bottle only needs to be opened if health is seriously compromised.
There are easier and more delicate oils that can take its place, but if you find nasty bacterial infections lurking in the house, it is a wonderful oil to use a drop on a hot flannel and wipe down surfaces, or to diffuse to send them on their way.
- Ernest D. Guenther. The essential oils. Vol. IV. [Online] 1950. http://onlinelibrary.wiley.com/doi/10.1002/jps.3030391222/abstract.
- The History of Fragrance from Cleopatra to Chanel. Morris, Edwin T. s.l. : Scribner, 1984.
- Essential Oil Safety For Professionals. Young, Robert Tisserand and Rodney. s.l. : Churchill Livingston (Second Edition), 2013.
- Cinnamomum camphora (Kapur): Review. Richa Singh, Talha Jawaid*. s.l. : Journal of Pharmacognosy, 2012, Vol. https://pdfs.semanticscholar.org/75c8/9d2aa6926d81024046c77693366d401a2a14.pdf.
- Weiss, Edward.Essential Oil Crops (Cabi). s.l. : Cabi Publishing , 1996.
- Camphor modulates TRPV3 cation channels activity by interacting with critical pore-region cysteine residues. Sherkheli MA, Vogt-Eisele AK, Weber K, Hatt H. s.l. : Pakistan Journal of Pharmaceutical Sciences, 2013. https://www.ncbi.nlm.nih.gov/pubmed/23625413.
- Vibrational Healing: Revealing the Essence of Nature Through Aromatherapy. Eisden, Deborah. s.l. : Frog Books , 2000.
- The Effect of Camphor on Sex Hormones Levels in Rats. al., Sima Shahabi et. s.l. : Cell Journal, 2014.
- Marasini BP, Baral P, Aryal P, Ghimire KR, Neupane S, Dahal N, Singh A, Ghimire L, Shrestha K. Evaluation of antibacterial activity of some traditionally used medicinal plants against human pathogenic bacteria. [Online] 2015. https://www.ncbi.nlm.nih.gov/pubmed/25738151.
- Streptococcus (Chapter 13) Medical Microbiology. Patterson., Maria Jevitz. s.l. : https://www.ncbi.nlm.nih.gov/books/NBK7611/, 1996.
- The Chemical Composition of Essential Oils from Cinnamomum camphora and Their Insecticidal Activity against the Stored Product Pests. Guo S, Geng Z, Zhang W, Liang J, Wang C, Deng Z, Du S. s.l. : International Journal of Molecular Sciences, 2016, Vol. Nov.
- Acaricidal activity of compounds from Cinnamomum camphora (L.) Presl against the carmine spider mite, Tetranychus cinnabarinus. Chen Y, Dai G. s.l. : Pest Management Science, 2015, Vol. Sept.
- Camphor poisoning: An unusual cause of seizure in children. Chaitali Patra, Shatanik Sarkar, Malay Kumar Dasgupta, and Amit Das. s.l. : Journal of Neuroscience, 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4395957/.
- Hepatotoxicity of monoterpenes and sesquiterpenes. Zárybnický T, Boušová I, Ambrož M, Skálová L. s.l. : Archives of Toxicology, 2017, Vol. Sept.