Sometimes when we think about skincare, the assumption is that natural is best (this might also be a product of green washing or the clean beauty boom, but I digress).

Essential oils fall firmly in the natural camp. They come up in beauty a lot, both for their wellness benefits and the so-called impact they can have on skin health. But for every proponent, there's a report or expert telling us to steer clear. They can also be found in a lot of product formulations. It's confusing the say the least.

So are they dangerous, beneficial, or somewhere in between? The answer – as it often is in the context of skincare – is not straightforward. But it is a good lesson in why 'natural' ingredients aren't always the ones we should reach for.

Read on for an explainer.

What are essential oils?

Essential oils are highly concentrated, aromatic compounds extracted from plants, typically obtained through distillation, or mechanical methods like cold pressing. They're generally used topically on the skin or in aromatherapy, a holistic practice that involves inhaling essential oils for therapeutic benefit (for example, using lavender essential oil to promote sleepiness).

The skincare benefits

When it comes to essential oils, it's not all bad. Many of them contain antioxidants and fatty acids that have protective and nourishing properties. There's evidence to show that others have antimicrobial effects. Tea tree oil is a prime example, and because of this, it's widely used in the treatment of acne and breakouts.

But these benefits alone aren't always enough to earn them a spot in your skincare routine. The production of essential oils isn't regulated, so it can be tricky to know exactly what you're using. They're also potent and often mixed with other extracts; if the formula isn't properly diluted, adverse reactions can occur (more on that below).

But on that note, it also depends on your definition of what constitutes a benefit. If the goal is to feel energised of a morning, and that involves a drop of bergamot in your body cream with no adverse effects, go forth. But if you have real complexion concerns, there are other ingredient options available with much more evidence to back their efficacy.

And the risks

Now for the caveat. "Essential oils contain some of the most potent skin allergens out there," explains New York dermatologist Dr Whitney Bowe. This is a particular concern for anyone prone to sensitivity, or with an existing condition like rosacea or dermatitis.

Some oils are also what's known as photo-toxic or photosensitising, meaning they can react negatively with UV rays, causing sunburn or hyperpigmentation (dark spots or marks that are difficult to get rid of). Dr. Bowe notes that citrus is the worst offender here: lemon, lime and grapefruit specifically.

In some cases, essential oils can disrupt the skin's natural barrier, leading to dryness, flaking and inflammation. Initially things might look and feel fine, but the continued application can be cumulative, and you might find your skin acting up a few months down the track. Some to avoid, according to Dr. Bowe? Cinnamon, clove, lemongrass, oregano and jasmine.

In conclusion...

There's no one size fits all approach when it comes to skincare; essential oils are no different. For the most part, it seems safest to steer clear. But that's not to diminish their wellness or therapeutic benefits. If you've used them as part of your wider routine for years with no issues, carry on. But if you're wondering if they're a holy grail, or alternatively find your constantly red/irritated/breaking out, omit them.