Essential oils have a long history: they’ve been used as home remedies for hundreds of years. They’re very popular among the Paleo crowd because they’re cheap, widely available, and perceived as more “natural” than taking medication. Unfortunately, historical use doesn’t necessarily guarantee effectiveness (people also used to prescribe radiation therapy as a cure-all!), and “natural” is not a synonym for “good.” Being traditional or natural doesn’t mean that essential oils are actually effective – for that, we need a different kind of evidence.
Actual scientific evidence for essential oils in humans (as opposed to test tubes) is thin on the ground, and most of the studies have important problems. For example, it’s very hard to control for the placebo effect in aromatherapy: how do you come up with an effective placebo that makes people think they’re smelling peppermint when they’re actually not?
With that said, though, here’s a report on the studies that have been done, and what essential oils they suggest as potentially helpful for various different problems.
How are Essential Oils Used? Are They Safe?
Before getting into whether or not they’re effective, the first question is whether or not they’re even safe to use (bleach is a very effective antimicrobial, but you still wouldn’t drink it!).
Essential oils are typically applied in one of three different ways:
- Mix them with a neutral oil or blend them into cosmetics (e.g. soap) and rub them on your skin. (topical application)
- Smell them with or without touching them (aromatherapy or massage aromatherapy)
- Put them in a pill capsule and swallow them. (ingestion)
Different grades of essential oils are sold for different purposes; something that’s safe to put in a candle is not necessarily safe to eat.
In fact, it can be very dangerous to ingest essential oils – just because they’re “natural” doesn’t mean they’re safe. It can also be dangerous to rub them on your skin undiluted; they can cause painful rashes or other skin symptoms (that’s why all the studies of topical application put them in a neutral oil or a cream).
If you’re using the appropriate grade of essential oil for what you’re doing, diluted to the proper concentration, and if you don’t have any individual allergies to it, then essential oils are pretty safe. But you are ultimately the one in charge of reading the warning labels and making sure you’re safe, especially if you’re mixing up your own cosmetics at home.
Studies on Essential Oils
With that said, here’s a look at some potential uses for essential oils that are actually supported by studies in humans.
Antimicrobial/Antibiotic Effects
Various different oils have proven effective as antibacterial agents, especially against antibiotic-resistant bacteria. Tea tree oil in particular is notable for its strength. In fact, there’s even some support for the idea that they might be able to help with the increasingly terrifying problem of antibiotic-resistant infections on factory farms.
In terms of personal use, this means that soap, shampoo, or cleaning products made with tea tree or other essential oils have some support for antimicrobial benefits. This study, for example, found that a 5% tea tree oil hand wash was significantly more effective than regular soap for handwashing. This study found that tea tree oil creams and body washes were as effective as standard treatment for getting rid of multidrug-resistant staph (MRSA) – that name might stick out to you as one of the nastiest drug-resistant superbugs around.
In other words: yes, essential oils have the potential to be life-saving antimicrobials. This is more relevant to hospital and farm settings than individual homes (most people aren’t culturing MRSA on their kitchen counters), but it’s potentially a big benefit to anyone who might need an antibiotic down the line. And essential oils don’t seem to be as hard on the gut flora as antibiotics are, which could potentially be a huge benefit for people who use them.
On a more prosaic note, the antimicrobial activity of tea tree oil in particular also makes it a pretty decent topical treatment for acne. And at least one study has also found it effective for dandruff when it’s mixed into shampoo. Antimicrobial superhero oil: working to make you look good for date night.
Stress, Anxiety, and Depression
For a slightly less serious but still important set of benefits, how about stress or anxiety reduction? A few different types and blends of essential oils have been tested for this:
- Lavender: there’s some evidence that it helps people get to sleep, helps reduce anxiety in a dental waiting room, and helps reduce agitation in patients with dementia.
- Rose: a reasonable amount of evidence supports the ability of rose oil to reduce anxiety especially if used in conjunction with other therapies (e.g. in a massage oil).
This study also found that clary sage had an antidepressant effect.
On the other hand, a Cochrane review found that aromatherapy massage shows some short-term benefits for psychological health in patients with cancer, but it’s not clear whether the aromatherapy (with any combination of oils) delivers any additional benefits above and beyond the massage.
Gut and Digestive Symptoms
Did your mother ever tell you to drink peppermint tea for an upset stomach? The tea might be soothing because it tastes good, but it probably doesn’t have enough bioactive compounds to actually be effective.
Essential oils, on the other hand, have concentrated bioactive compounds in spades, and there’s an increasing amount of evidence that peppermint oil in particular is effective for managing symptoms of Irritable Bowel Syndrome and other functional GI disorders, if it’s swallowed in a special kind of coating called enteric-coated tablets. The point of these is that they protect the essential oil as it passes through the stomach, so it doesn’t get digested by the stomach acid. That way it actually gets through to the gut.
Other Benefits
And now for the grab-bag: there are a few isolated studies showing various unrelated benefits to various other oils.
- Lung and respiratory symptoms: Remember Vick’s Vap-O-Rub? That has essential oils in it too, specifically eucalyptus, and there is some evidence that eucalyptus can help with respiratory symptoms.
- Menstrual symptoms: This study found that massage with an essential oil blend (cinnamon, clove, rose, and lavender) was more effective than massage with a placebo oil at relieving menstrual pain. This study found the same thing, but with a blend of lavender, clary sage, and marjoram. On the other hand, evening primrose oil probably doesn’t do much for PMS, despite its advertising.
This review covers many other oils and uses, but many of them (for example, the hypothetical anticancer and cardiovascular benefits) have only really been studied in test tubes or in rats – that just isn’t solid evidence that they work the same way in humans.
Summing it Up
Essential oils may or may not work as advertised. It’s very hard to tell because so little actual research has been done on them. A systematic review of systematic reviews, for example, concluded that there simply wasn’t convincing evidence that aromatherapy with any oil or combination of oils is effective to treat any particular disease.
The very small amount of research we have indicates that there might be a use for peppermint oil in treating gastrointestinal symptoms, and lavender or rose oil for relieving stress. Tea tree oil also has some cosmetic uses, especially in fighting acne and dandruff. Probably the most exciting and well-researched benefit is that essential oils are effective antibiotics even when they’re pitted against drug-resistant bacteria. Considering that the world’s antibiotic supply is in crisis, any new weapon against drug-resistant superbugs is a welcome addition to the arsenal.
Of course, there’s nothing wrong with using essential oils in your home or your cosmetics just because you like the smell; they do smell good and there’s no reason not to enjoy that. Not everything has to be a miracle cure for cancer! But if you do use them, just make sure to carefully research the proper doses and application, and bear in mind that most of the research is preliminary at best.
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