Tsuga essential oil with its spruce-like aroma is used primarily to treat the common cold and cough. It comes from an evergreen coniferous tree known as the Eastern Hemlock. In the Appalachians and eastern Canada, it has been used to prepare a soothing herbal tea that relieves nasal congestion. Its essential oil is made up of natural monoterpenes that make it a potent natural decongestant. New research from Japan indicates that it can be quite helpful in achieving relaxation and lower the attention to computer or mobile screens. Essential oils from coniferous trees with their medicinal yet earthy aromas are soothing to us.
Eastern hemlock is a beloved tree among people residing in states lining the Appalachian Mountains. Many of the eastern hemlock trees have been standing for well over 600 years which is no mean feat. Its scientific name is Tsuga canadensis. It is distinct and unique because it stays green throughout the year and is easily identified because of the characteristic small needles and short yet cute brownish pine cones. It has a much more fissured bark than surrounding conifers like pines. Its leaves have a distinct white line on the underside. Some older trees grow to be very tall, even up to 45 meters. Fresh needles are bright green, and herbal tea makers prefer them. Mature needles are noticeably darker in color.
Essential oil is distilled from the needles and twigs of this majestic tree. This magnificent tree is suffering grave threat from a pest known as the wooly Hemlock adelgid in our times. Therefore, its exploitation for essential oil making is self-restricted by the industry to ensure its sustainability and viability.
Color and Aroma
The color of pure Tsuga essential oil is clear white with a faint yellowish ring at the meniscus of the glass bottle in which it is kept. Its aroma is characterized as fresh and woody. It is similar to the essential oil of spruce. One would notice a characteristic forest attribute with strong hints of pine. This is because of the predominance of a monoterpene (a class of volatiles) that goes by the name alpha-pinene. Minor hints of camphor and earthy tones can be discerned. Some tips of turpentine, like aroma with spicy, sharp quality, can also be identified. This is the aroma of myrcene, a famous volatile compound found in many essential oils, including essential oils of coniferous trees. The aroma of Tsuga essential oil cannot be appreciated quickly. Although most of its constituents are fast evaporating and makeup only a top note of perfumery blends, some remnant aroma is still there.
Presently we do not have any modern studies delineating its therapeutic properties. Its usage in regional herbal medicine and aromatherapy provides us with only a minor fraction of the possible effects that it must be exerting.
- Analgesic – It is used to relieve muscular aches and buildup of stress caused by long hours of sitting and other such sedentary occupation-related body aches.
- Decongestant – It is diffused in the air to clear up the congestion in the nose and sinuses.
- Expectorant – It helps expel phlegm from the lungs, keeping our airways open and relaxed.
- Antibacterial – Both alpha and beta-pinene are strongly antibacterial against a very wide spectrum of bacteria.  They can be considered natural broad-spectrum antibiotics.
- Antifungal – Essential oils rich in alpha-pinene are strong killers of the candida Albicans yeast. This fungus is believed to be responsible for a host of irritating and foul-smelling fungal infections like oral and vaginal thrush. 
- Relaxant – Tsuga essential oil acts as a relaxant. It helps to calm down and achieve a relaxed state with a reduced pulse rate. Researchers at the Chiba University in Japan have pointed out that such an effect is observed in essential oils made rich in alpha-pinene wood. 
- Bradycardic – Tsuga essential oil may lead to a reduced pulse rate. 
- Anti–nociceptive – Essential oils from conifer tree barks and twigs are usually effective at soothing muscular aches and pains when used in a massage. This effect is most powerful when wintergreen oil or birch oil is used. Tsuga essential oil, like other oils of the pine family, also helps to alleviate pain.
- Neuroprotective – Very few essential oils exhibit this activity when they are diffused in the air. This effect is attributed to a special volatile compound known as myrcene, abundant in Tsuga essential oil. 
- Anti-tumor – Alpha pinene shines out when we try to select out essential oils that exhibit anti-tumor activity. But it is not clear whether a mere diffusion of any essential oil rich in alpha-pinene would be able to provide our body with adequate tumor-killing power. 
These therapeutic effects can make Tsuga essential oil a surprising new substitute for some of the other coniferous essential oils in essential oil blends. It also holds its ground because of the unique health benefits that it provides.
Health Benefits and Uses
Upon diffusing Tsuga’s essential oil into the living quarters, one would feel the mind calming down. The frequency and randomness of thoughts and processes that our brain keeps on carrying out every microsecond can be overwhelming sometimes. Essential oils of woods help with that. Their forest-like aroma with earthy tones is grounding and calming to the mind. They help us get comfortable in new surroundings, like when we go to a hotel or a new location.  We are always more at peace at our own home, and new places are often not so comfortable to our minds. Tsuga essential oil can be used when traveling, say on a business meet to a new city and residing in a hotel.
Tsuga essential oil can be substituted for cedarwood essential oil in essential oil blends used to alleviate coughing. European Pharmacopoeia recognizes the following essential oils as incredibly useful in treating upper and lower respiratory tract infections irrespective of whether bacteria or viruses cause them. These are – anise oil, bitter fennel fruit oil, eucalyptus oil (of course), peppermint oil (mainly because of menthol), tea tree oil, and the last is thyme essential.
Although Tsuga essential oil may not be as powerful an expectorant as anise seed oil or eucalyptus oil, it sure brings its decongestant and analgesic properties to the table. In conditions like a common cold or allergic rhinitis where we are in need of a decongestant, this essential oil can help.
Tsuga Essential Oil for Muscular Aches
Many of us have to deal with a long and tiring day consistently. Muscles in the lower back and even the middle back accumulate a lot of strain. Working long hours at a desk hurts the shoulder blades, upper back, and cervical region (backbone region of the neck) too. Such strain needs to work at, to dissipate it. An essential oil massage helps to reduce the pain caused by sore muscles. Tsuga essential oil and many other oils of the pine family are powerful at lowering muscular aches. But we must choose a suitable carrier oil to dilute essential oil before it can be worked into the skin. Sesame oil is considered to be the best for a pain-relieving massage. Add four drops of Tsuga essential oil to about 30 ml of sesame oil and mix it thoroughly. First, do a patch test on the hands to check if you are not sensitive to the mixture. For more severe conditions like muscular aches brought on by healing injuries, cramps, or muscle sprains, sessions with a certified massage therapist would be better.
Not much is known about the in-depth chemical composition of Tsuga canadensis essential oil. It is only recently that the species is receiving the attention of researchers because it is being infested with a debilitating pest infection. In one such study, it was found that the tree is producing a greater quantity of essential oils to try and ward off the pest.
Three compounds make up more than 75% of the essential oil. These are alpha-pinene, camphene, and myrcene.  We have extolled the virtues of alpha-pinene in the section on properties. Myrcene is a volatile compound that reduces the chances of getting a peptic ulcer. It is also anti-catabolic and neuroprotective.  Camphene is much more prevalent in the plant world. It is known for its pain-relieving capabilities. It also has anticancer activity against melanomas. 
Other volatile essential oils found in Tsuga essential oil are beta-pinene, alpha and beta phellandrene, terpinolene, limonene, and bornyl acetate. Limonene is of great interest as it is the chief component of citrus essential oils. It is a potent inhibitor of cancer of the breast and colorectal region. It is also powerful as an anti-stress compound. 
The balsamic aroma detected in almost all pine oils is credited to bornyl acetate. When they want their product to smell like a pine forest, most firms add a few drops of pure bornyl acetate to the soap, shampoo, conditioner, candle, etc. A study in the Biomedical Research journal reports that the aroma of bornyl acetate affects the activity of the autonomic nervous system (the mechanism that drives our major bodily functions) in such a way as to create a feeling of relaxation. It also reduces the level of attentiveness when working on computer and video screens.  This is quite helpful for people wanting to let go of their work or the addiction to social media or games on their mobile devices late in the night and try to get some relaxation and maybe get an early sleep.
Side Effects and Toxicity Issues
Since Tsuga essential oil belongs to the category of pines, it should not be ingested. Essential oils of such conifers should be used in the diffuser and for topical use only. Care should be taken that the room in which its aroma is diffused should be well ventilated so that the concentration of Tsuga essentials does not become too high. Essential oils diffused at greater strengths can overdo the health benefit. In this case, strong diffusion of Tsuga essential oil may lead to feeble pulse and respiratory distress. Its toxic dosage is not known. However, it can act as a skin irritant. One should stay on the safe side and diffuse only a weak solution (2 to 4 drops per 100 ml in the diffuser). It should not be used in the presence of children below the age of 18 and pregnant women and lactating mothers.
Buying and Storage
Tsuga essential oil comes mostly from Canada and the USA. Responsible firms report that they only use trees that have fallen during natural calamities, and no additional felling is done. This is extremely relevant in Eastern Hemlock because of the severe threat it faces from the notorious pest.
Since the oil is almost entirely made up of monoterpenes, it has a very low shelf life. It may not even last an entire year. Such oils with low shelf life must be bought in smaller quantities only and kept refrigerated.