Exploring the Potential Toxic Effects of Essential Oils

Pure essential oils australia have become the go-to remedy for everything from stress relief to soothing muscle aches. They’re the fragrant darlings of the wellness world, promising a little slice of botanical bliss in every drop. But as with all powerful substances, there's a flip side to consider. What happens when we go overboard or forget that essential oils are, well...essentially potent?

While most people use essential oil for sleep, there are some risks to keep in mind—especially when it comes to high doses or long-term internal use. Fortunately, the way most of us use them—like in aromatherapy massages—is pretty low-risk. The skin absorbs essential oils slowly, which is why topical use is much safer. Still, even with topical application, it’s wise to be aware of potential reactions like allergies, irritations, and sensitivity to sunlight.

Let’s take a closer look at what can go wrong with essential oils and, more importantly, how to avoid it!

1. Allergenic Reactions: How to Spot Them

Some older studies suggest that oils high in monoterpene hydrocarbons, like citrus and pine oils, can cause sensitivities. However, it’s not typically the terpenes themselves but rather compounds called hydroperoxides—formed when these oils break down due to exposure to oxygen—that trigger the allergic responses. This is why proper storage and use of oils within their “use by” dates are so important. If a citrus oil no longer smells fresh like the fruit it came from, it’s time to toss it.

There are also compounds called sesquiterpene lactones, which are found in oils like massoia bark and bay laurel, that have been linked to allergic reactions. However, these oils aren’t typically part of this discussion. Another one to keep in mind is tea tree oil, which, despite being widely used, can occasionally cause allergic reactions in some people, including dermatitis. Most people can use tea tree oil without any issue, but a small percentage may experience more severe reactions.

Allergic reactions to essential oils are often unique to the individual. In some cases, the oils may act as a "trigger" for an underlying issue rather than being the direct cause of the reaction. So, if you're ever unsure about how your skin might react, it’s always a good idea to patch test first. Simply apply a small amount of a 5% or 10% dilution of the essential oil to a spot like the inner arm or the breastbone. If you're going to react, it usually happens within a few hours, but it could take up to 24 hours. If you're still uncertain, some people find tools like Touch for Health muscle testing helpful in determining potential reactions. It’s always better to be safe than sorry!

2. Irritant Reactions: What to Watch Out For

Unlike allergies, irritant reactions occur when certain essential oils are too potent for the skin. Oils with high levels of phenolic compounds—like Thyme, Oregano, and Clove—can be harsh, especially on sensitive areas or mucous membranes. These oils can cause burning or skin damage if applied without care. Similarly, Cinnamon Bark and Cassia oils are known for their “burning” power, which is why aromatherapists often advise caution when using them topically.

Even seemingly mild oils like Peppermint or Lemongrass can cause irritation, especially in water-based applications like baths. It’s all about the dosage—what might be a soothing drop in a massage oil could become an irritant if added in excess to bathwater. Unlike allergies, irritant reactions happen quickly, usually within minutes.

3. Phototoxic Effects: Sun Safety and Essential Oils

Did you know that some essential oils can make your skin more sensitive to sunlight? This is called phototoxicity and is caused by compounds like coumarins, which are found in oils like Bergamot and other citrus varieties. These compounds can absorb UV radiation and pass it to your skin, leading to faster sunburns or even lesions. Long-term use of phototoxic oils in perfumes has been linked to conditions like berloque dermatitis, where skin pigmentation increases.

The takeaway? If you’re using phototoxic oils, avoid direct sunlight for at least 12 hours after application, or opt for sun-safe versions of those oils that have had the risky compounds removed.

4. Narcotic Effects: When Essential Oils Get Too Strong

Most of us think of essential oils as calming, but did you know that at very high doses, some can have narcotic-like effects? These oils can cause feelings of stupor, paralysis, or even a general shutdown of bodily functions. While this doesn’t happen under normal use, it’s still important to be aware of.

Oils containing ketone compounds — like thujone (found in oils like Wormwood and Sage) or apiol (from Parsley seed) — are typically responsible for these effects. Other oils, like Nutmeg (which contains myristicin), can also have psychoactive effects. On the flip side, oils like Clary Sage and Laserwort can sometimes create euphoric feelings, but again, this is generally with low doses and doesn’t appear to be toxic.

5. Abortifacient Effects: A Risk to Pregnancy

Some essential oils have been used throughout history to stimulate the uterus and even induce abortion, but this should never be attempted without medical supervision. Oils with high levels of ketones, such as Pennyroyal and Apiol, have been known to cause uterine contractions. When used in excessive amounts, these oils can cause toxic damage to vital organs like the liver, so it’s crucial to avoid them during pregnancy.

If you're pregnant, always err on the side of caution and consult your healthcare provider before using essential oils.

6. Hepatotoxic Effects: Protecting Your Liver

Using essential oils can have some serious side effects if not handled with care, particularly when it comes to your liver. The liver is the body's primary detox centre, processing and breaking down compounds—including those found in essential oils. If essential oils are used in extremely high amounts, they can potentially cause liver damage, either from a single large dose (acute) or from prolonged use over time (chronic).

Take clove bud oil, for example. It's rich in a compound called eugenol. The liver uses an amino acid called glutathione to safely process eugenol. However, if you go overboard, the liver can run out of glutathione. At that point, eugenol can turn toxic in the body.

Another example is eucalyptus oil. When taken in high doses orally over a long period, it has been linked to liver issues, even cirrhosis—similar to the damage caused by excessive alcohol consumption. Essentially, just like alcohol, repeated high doses of essential oils can lead to significant liver damage over time.

7. Nephrotoxic Effects: Taking Care of Your Kidneys

The potential for essential oils to irritate the kidneys is still a bit of a mystery. For years, Juniper oil was thought to cause kidney irritation when used in high doses—a belief that dates back to 1898. However, a study presented at the 24th International Symposium on Essential Oils in Berlin back in 1993 suggested this concern might have been based on a misunderstanding.

In those early studies, researchers gave animals huge doses of Juniper oil, which caused cloudiness in the urine. This was initially seen as a sign of kidney irritation. However, it turns out that this cloudiness was likely just the body's way of getting rid of the metabolites from the oil, not actual kidney damage. A more recent study using high doses of Juniper oil in lab rats found no harm to the kidneys. Interestingly, the study used a Juniper berry oil with lower levels of certain compounds, like terpene hydrocarbons, which can sometimes be a bit rough on the urinary tract.

That said, it’s still possible that some of the earlier concerns about Juniper oil causing kidney irritation could have come from oils with high levels of pinene, a compound that can be irritating. Even though Juniper berry oil does have quite a bit of pinene (34-46%), it's still less than what's found in Juniper branch oils, which can range from 40% to 90%.

Other essential oils, like Sandalwood and Gum Turpentine, have also been flagged in older studies as potential kidney irritants. So, what does this all mean? In general, essential oils are considered safe when used in recommended doses. But if someone already has kidney issues or decreased kidney function, it's wise to be cautious. In those cases, reducing the dosage of oils like Pine, Juniper, and Sandalwood is a smart move.

8. Carcinogenic Effects: Proceed with Caution

Sassafras oil and calamus oil have both stirred up some controversy due to their chemical makeup. Sassafras oil contains a compound called safrole, and calamus oil has asarone—both of which have shown potential cancer-causing effects in studies where they were given to lab animals in large doses over extended periods. As a result, calamus oil is banned in food products, and sassafras oil is considered a toxic substance if used above a 1% concentration.

But here’s the interesting part: what happens in animal studies doesn’t always translate directly to humans. Some French research has suggested that safrole might metabolise differently in humans compared to rats, forming non-cancer-causing compounds in people. It’s also crucial to remember that those studies involved extremely high doses over long periods, not the occasional small doses some people use.

With that in mind, we often recommend using sassafras oil in low doses, especially when blended with other essential oils. It can be quite effective for pain relief in muscular issues. So, occasional and mindful use of sassafras oil, particularly for its pain-relieving benefits, shouldn’t raise the same concerns as those high-dose studies on lab animals.

The LD50 Test: What Is It, and Why Should You Care?

You might have heard of the term LD50 (lethal dose for 50% of test subjects), a standard measure used in toxicity testing. Essentially, it’s the dose at which 50% of laboratory animals would be expected to die from exposure. While it’s not the most pleasant test to think about, it’s still widely used to estimate the potential toxicity of various substances, including essential oils.

For example, an LD50 value of 1 means that 1 gram of essential oil per kilogram of body weight is the lethal dose for 50% of test animals. Let’s break this down: if the test subject weighs 70 kg (about the average human weight), an LD50 of 1 would suggest that 70 grams of essential oil could be fatal.

But here's the catch: while these tests help give us a rough idea of how toxic a substance might be, the results aren’t always directly transferable to humans. Animal metabolism can differ from human metabolism, and toxicity varies based on many factors—so we can’t make exact predictions about human safety from animal studies alone. Still, the information can provide helpful guidelines for determining safe dosages for essential oils.

How to Stay Safe: Toxicity Ratings

To help you navigate the world of essential oils safely, experts have created toxicity ratings based on the LD50 tests. Here's a quick breakdown:

1. Rating 1 (High Risk): Oils with an LD50 of less than 1 are considered toxic. These oils should only be used in very small doses and, typically, only for specific applications like inhalation. Always proceed with caution, especially with young children or pregnant women.
2. Rating 2 (Moderate Risk): Oils with an LD50 between 1 and 2 are still useable in aromatherapy, but they require more caution. Always be mindful of the dosage, and consult with a professional before using these oils on children, during pregnancy, or for long periods.
3. Rating 3 (Safe for Long-Term Use): Oils with an LD50 greater than 2 are considered safe for regular use in aromatherapy, including for children and pregnant women. These oils are ideal for long-term applications and are generally regarded as safe when used in appropriate dosages.

Toxicity vs Application Method

Looking at the graph above, it’s clear that methods like massage and inhalation therapy—commonly used in Aromatherapy—are generally considered non-toxic or have the least potential for toxicity. There are two main reasons for this:

1. When essential oils are used with carrier oil, they’re absorbed gradually over time rather than being quickly absorbed as with internal use.
2. Since essential oils are often inhaled or applied topically, not all of the dose actually enters the bloodstream, as evaporation and other factors reduce how much is absorbed.

Different skin absorption times of various aromatic molecules and essential oils

The effect of vehicles on the absorption of fragrances through the skin was studied using unoccluded application sites. The experiment involved four monkeys, with each monkey used to test all the compounds. For this study, benzyl alcohol and benzyl benzoate were applied to the skin in a 10mg lotion per cm² dose, while benzyl acetate was applied in a higher concentration of 30mg lotion per cm². The results were measured as averages with standard error of the mean (SEM).

Conclusion

Essential oils have powerful therapeutic benefits but must be used responsibly to avoid potential toxic effects. Proper dosage, correct application methods, and awareness of individual sensitivities are essential for safe aromatherapy practice. Always consult professionals or conduct patch tests when uncertain, especially for vulnerable populations like children and pregnant women.

If you are looking for high-quality, pure essential oils, be sure to purchase from reputable brands and suppliers such as Amrita Court Global. We are committed to providing safe and effective essential oils for all your aromatherapy needs. With proper knowledge and responsible usage, you can experience the many benefits of essential oils without any negative side effects. Let us help you on your journey towards holistic well-being today!