Parsley oil is the essential oil extracted mainly from the seeds of parsley. It can also be made from the roots or the leaves, but that is less preferred. These seeds are aromatic, and the oil bears a strong resemblance to the aroma of parsley. In aromatherapy, it is used for diverse purposes, and it also blends with many of the other common essential oils. There is an interesting anecdote about parsley. Hippocrates of Kos (a renowned naturalist in ancient Greece) noted that parsley could induce abortions. Later on, a compound called apiol was responsible for parsley’s effect of causing uterine contractions. Now that we have gotten this scary information about parsley, it is prudent to pay heed to its many health benefits.
Parsley essential oil is obtained by steam distillation of the aromatic seeds that grow on the topmost part of the parsley plant. Although its leaves are also aromatic, they are not generally used for producing commercially available parsley oil.
The parsley plant is known as Petroselinum crispum. So, the name itself gives away its crispy aroma! It belongs to the same biological family as coriander (also known as Chinese parsley), producing aromatic seeds and flavorful leaves for use as garnishing. But, there are some differences between the two. While parsley is native to the Mediterranean, coriander is native to the Middle East.
Even among parsley, we have two superior cultivars, the Italian parsley (which is flat-leaved) and the other one is a curly leaf variety. Italian parsley has a stronger flavor.
Color and Aroma
When seen in a pure glass bottle, the essential oil is milky white with a bright yellow ring at the meniscus (topmost surface of the oil). It is usually kept in amber-colored bottles so that bottle shows a tinted color. Its aroma, made of many ingredients, is woody and herbaceous. Still, it has slight elements of spiciness (which gives it a mild sharp and astringent appeal) and some tanginess (because of a small amount of a compound called limonene). But when its aroma is compared to the aroma of the leaf, we find that the essential oil is more bitter. This is possible because of the enrichment of volatile compounds in the seed, making the aroma much stronger.
Parsley seed essential oil has many documented therapeutic properties.
- Immuno-modulatory – Sometimes, our immune system goes into overdrive and tends to cause havoc inside the body. An overactive immune system can cause allergies and autoimmune conditions (where the immune response kills our body cells), and inflammation. Parsley essential oil has shown the ability to suppress such a response to some extent. 
- Anti-fungal – Parsley essential oil is a potent inhibitor of food-borne fungi. People who live in hot and humid climates are much more troubled by fungi growing on fruits and vegetables, like carrots. The aroma of this oil can keep the fungi at bay and keep your vegetables fresh for longer. 
- Anti-bacterial – Similar to its anti-fungal effect, it is also effective against bacteria that reside on food and then lead to food-borne illnesses.  The essential oil has a dual mode of action – firstly, it prevents the further growth of bacteria, and secondly, it kills the existing bacteria. It is also effective against bacteria that cause urinary tract infections like Escherichia Coli (E. Coli in short) and Staphylococcus aureus (S. aureus). Rosemary essential oil also has a similar effect on bacteria that tend to mushroom up on food.
- Carminative – Parsley essential oil inherits the carminative property of parsley seed and amplifies it. This makes it ideal for relieving minor stomach troubles caused by gastritis (build-up of gas) in the intestines. Thus, it can help nausea, bloating, and the discomfort associated with it.
- Antioxidant – Its aromatic constituents help the body to kill free radicals.
- Antispasmodic – The seeds of parsley have been used to relieve colicky pain for ages. It works by reducing the spasms in the intestinal muscles that cause sharp, periodic pain. Parsley seed essential oil to obtains this property from the seeds. Combined with the carminative action, parsley oil becomes a natural choice for aromatherapy in gastric complaints.  This effect is attributed to a compound called apiol.
- Anti-inflammatory – A compound called Apigenin found in the essential oil extracted from parsley seeds has a potent anti-inflammatory effect inside the body. 
- Anti-rheumatic – Apigenin-containing essential oils help reduce the specific mechanism of inflammation, which aggravates rheumatoid arthritis. 
Apart from these powerful therapeutic effects, the aromatic oil can also boost appetite and eliminate excretion by acting as a mild laxative.
Effects on women
Parsley seed oil is quite effective in relieving many of the issues that accompany heavy menstruation. It reduces cramps brought about by the loss of electrolytes. It is also known to induce timely periods, thus reducing amenorrhoea. The menstrual cramps can also affect the proper digestion of food, which can be improved by smelling parsley essential oil.
However, it is a known abortifacient, which can induce spontaneous contractions (bring on labor) and cause a miscarriage. Hence, it should never be used by pregnant women.
Health Benefits and Uses
Parsley oil for Acne and Pimples
The essential oils in parsley help get toned blemish-free skin as it helps keep acne and pimples to a minimum. However, one should not apply parsley seed essential oil directly on the skin as it makes the skin extra sensitive to the sun. It can even cause photo-dermatitis (an inflammatory reaction by the skin impacted by sunlight).
But, we should not be discouraged. A more-gentler parsley based herbal oil can be prepared for use on the skin, and this one only uses parsley leaves and not the essential oil. Here is the formulation.
Facial Toner using Parsley leaves, Tea Tree essential oil, and Apple Cider Vinegar
The base of this mixture is prepared by boiling a handful of parsley in about 250 ml of water. The parsley steeps into the water and forms an aqueous extract. Boil till the mixture remains about the size of half a cup. Then strain the liquid and add 20 drops of tea tree essential oil (organic) and a very small amount of apple cider vinegar (half a teaspoon). The important thing is to mix it well and fill it in a suitable bottle for storing essential oils. Close it up with a cork to become air-tight and keep it in the dark, cool place. This mixture can be used as a toner for the face. Just pour a few drops onto a cotton ball and apply it evenly to the face. Ideally, this should be done at night so that even the minor photosensitizing effects of parsley leaves lose their strength. The apple cider vinegar creates an inhospitable medium for the bacteria that cause acne and pimples. The oily resins from parsley leaves complement tea tree essential oil in reducing inflammation and redness.
Parsley Oil in Aromatherapy
Using a few drops of parsley essential oil in a diffuser is enough to spread its strong aroma throughout the living quarters. The volatile constituents diffuse into the air and enter our bloodstream through the respiratory tract. Its aroma is used to relieve a troubled stomach, nausea, indigestion, and a bloated belly. This is based on its solid carminative properties. It blends well with essential oil of anise, coriander, and ginger for obtaining this effect.
Parsley Oil to Alleviate Joint Pain and Redness
The ideal base oil for this essential oil is olive. Add about four drops of parsley essential oil is about 100ml of olive oil. Stir it well and keep the mixture in the dark and cool place. This formulation is then used to massage the joints of fingers and toes that show signs of arthritis, including swollen, reddish joints, increased friction between the bones, and a sharp, tearing pain. Although parsley essential oil cannot be in any way a sufficient remedy for such a powerful inflammatory condition, it assists in reducing the inflammation on the surface and alleviating the pain, albeit for a brief period.
Nutritional and Medicinal Information
In this section, we investigate the chemical composition of parsley seed essential oil and which volatiles contribute to its therapeutic properties.
Parsley seed essential oil is composed mainly of terpenes. This class of compounds is vast, and they are found in the oily parts of most plants. But, the variations in the percentages of these terpenes make up for major differences in the aroma and thus the properties of various essential oils.
Myristicin is a unique essential oil found in nutmeg and dill, and to some extent, in anise seeds. At high concentrations, it has been known to cause psychedelic effects and some negative consequences, like confusion, dizziness, very low blood pressure, and an altered mental state. This is believed to be the reason for the psychotic effects of nutmeg. Since parsley essential oil also contains a good amount of myristicin, it may also lead to such harmful effects, especially when you inhale strong oil concentrations. 
Alpha pinene (α-pinene) is quite helpful in respiratory issues. It acts as a bronchodilator; that is, it helps to open up the airways in the lungs, which aids in conditions like asthma and respiratory infections. Its aroma is more associated with that of pine.  Beta pinene (β-pinene) has an aroma similar to the overall aroma of parsley. It is believed to be an antiseptic and a potent anti-inflammatory substance.
Apiole (also called apiol) is the oleoresin part of this essential oil. Way back in the 1850s, it was found that this compound could be used to alleviate menstrual complaints. It had also begun to be used to induce an abortion. However, it was found to be harmful even to the kidneys and the liver at high doses. 
Parsley essential oil also contains a famous phytonutrient called Apigenin which is not a terpene. It belongs to an entirely different class of compounds called flavonoids. These are found in fruits and vegetables and also teas and wine. A major contribution to the health benefits provided by fruits is attributed to flavonoids. One of the most well-known flavonoids is catechin. Apigenin is a powerful antioxidant. It is known for its ability to boost memory and cognitive performance. Thus, it is believed to aid in forming nerve cells in our brain, prevent brain cells from damage, and even prevent conditions like Alzheimer’s. 
Side Effects, Safe Dosage, and Toxicity Issues
The essential oil of parsley makes the skin photosensitive. It may even cause skin irritation in some people when applied topically. Therefore, it should not be applied to the skin without performing a patch test. When using aromatherapy, make sure to use only a few drops of this oil, and one can complement the aroma with other essential oils that go with it. This is because, as we have discussed, myristicin in it may cause health problems. It should never be ingested. Therefore, it should be kept away from the reach of kids as its smell may attract them and accidentally add it to their food or try to drink it. Doing this can be fatal. Hence, essential oils should be bought, stored, and used with a good measure of caution as hazardous when not used properly.
Buying and Storage
I always prefer steam-distilled essential oils. These are very pure and have a powerful aroma, and thus, they are costlier than solvent-assisted extractions. One should always go for a reputed manufacturer and also note the country from where the parsley has been obtained. This is important because a plant grows well only in the climatic region in which it natively grows. For example, Mediterranean climate plants would have different properties if they succeed in southeast Asia’s monsoon climate. Best quality parsley grows in the Mediterranean climatic zones of Europe and North Africa (like Morocco), the Middle East, and California. In Italy, for example, parsley is used in so many sauces and pastes, a popular one being the gremolata.
Any essential oil is quite fragile when it comes in contact with heat and light. It should be kept in the bottles where it arrived as they are lab tested for keeping these volatile oils. It should also be kept chilled at around 5° C. That is the way to maintain its integrity and aroma.
- Immunomodulatory effect of Parsley (Petroselinum crispum) essential oil on immune cells: mitogen-activated splenocytes and peritoneal macrophages. Yousofi A. at al. Immunopharmacology and Immunotoxicology.
- Anti-fungal and anti-bacterial activities of Petroselinum crispum essential oil. Linda GA et al.Genetics and Molecular Research GMR.
- Chapter 23 – Petroselinum crispum – a Review. C. Agyare et al. Science Direct.
- Anti-inflammatory mechanisms of Apigenin: inhibition of cyclooxygenase-2 expression, adhesion of monocytes to human umbilical vein endothelial cells, and expression of cellular adhesion molecules. Lee JH et al. Archives of Pharmacal research.
- Chemical Composition, Antioxidant and Antimicrobial Activity of Essential Oils from Organic Fennel, Parsley, and Lavender from Spain. Irene Marin et al. Foods 2016.
- Myristicin – PubChem.
- Alpha-Pinene – Wikipedia.
- Apiol – Wikipedia.
- Apigenin and related compounds stimulate adult neurogenesis. Philippe Taupin. Journal of the Expert opinion on therapeutic patents.