Dos and Don’ts of Essential Oils (2024)

Written by Paul Frysh

Simple smells such as lavender, chamomile, and rosewater may help keep you calm. You can breathe in or rub diluted versions of these oils on your skin. Scientists think they work by sending chemical messages to parts of the brain that affect mood and emotion. Although these scents alone won’t take all your stress away, the aroma may help you relax.

Oils that are fine on your arms and legs may not be safe to put inside your mouth, nose, eyes, or private parts. Lemongrass, peppermint, and cinnamon bark are some examples.

Look for a trusted producer that makes pure oils without anything added. You’re more likely to have an allergic reaction to oils that have other ingredients. Not all extras are bad. Some added vegetable oil may be normal for certain more expensive essential oils.

Just because it’s from a plant doesn’t mean it’s safe to rub on your skin, or breathe, or eat, even if it’s “pure.” Natural substances can be irritating, toxic, or cause allergic reactions. Like anything else you put on your skin, it’s best to test a little bit on a small area and see how your skin responds.

In general, don’t keep them more than 3 years. Older oils are more likely to be spoiled because of exposure to oxygen. They may not work as well and could irritate your skin or cause an allergic reaction. If you see a big change in the way an oil looks, feels, or smells, you should throw it out, because it has probably spoiled.

Cumin oil, which is safe to use in your food, can cause blisters if you put it on your skin. Citrus oils that are safe in your food may be bad for your skin, especially if you go out into the sun. And the opposite is true, too. Eucalyptus or sage oil may soothe you if you rub it on your skin or breathe it in. But swallowing them could can cause a serious complication, like a seizure.

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Your doctor can make sure it’s safe for you and rule out any side effects, like affecting your prescriptions. For example, peppermint and eucalyptus oils may change how your body absorbs the cancer drug 5-fluorouracil from the skin. Or an allergic reaction may cause rashes, hives, or breathing problems.

Undiluted oils are too strong to use straight. You’ll need to dilute them, usually with vegetable oils or creams or bath gels, to a solution that only has a little bit -- 1% to 5% -- of the essential oil. Exactly how much can vary. The higher the percentage, the more likely you are to have a reaction, so it’s important to mix them correctly.

Injured or inflamed skin will absorb more oil and may cause unwanted skin reactions. Undiluted oils, which you shouldn’t use at all, can be downright dangerous on damaged skin.

Young children and the elderly may be more sensitive to essential oils. So you may need to dilute them more. And you should totally avoid some oils, like birch and wintergreen. In even small amounts, those may cause serious problems in kids 6 or younger because they contain a chemical called methyl salicylate. Don’t use essential oils on a baby unless your pediatrician says it’s OK.

They can be very concentrated and may cause serious health problems, especially if used at the wrong dose or in the wrong way. Just like anything else that little hands shouldn’t be able to reach, don't make your essential oils too handy. If you have young children, keep all essential oils locked away out of their sight and reach.

Your skin might love essential oils. But if it doesn’t -- and you notice a rash, little bumps, boils, or just itchy skin -- take a break. More of the same oil can make it worse. Whether you mixed it yourself or it’s an ingredient in a ready-made cream, oil, or aromatherapy product, gently wash it off with water.

If you look for a professional aromatherapist, do your homework. By law, they don’t have to have training or a license. But you can check to see if yours went to a school certified by a professional organizations like National Association for Holistic Aromatherapy.

More of a good thing is not always good. Even when diluted, an essential oil can cause a bad reaction if you use too much or use it too often. That’s true even if you’re not allergic or unusually sensitive to them.

Used the right way, they can help you feel better with few side effects. For example, you may feel less nauseated from chemotherapy cancer treatment if you breathe in ginger vapors. You may be able to fight certain bacterial or fungal infections, including the dangerous MRSA bacteria, with tea tree oil. In one study, tea tree oil was as effective as a prescription antifungal cream in easing symptoms of a fungal foot infection.

Some essential massage oils may make their way into the placenta, an organ in your uterus that grows along with your baby and helps to nourish it. It’s not clear if this causes any problems, unless you take toxic amounts, but to be safe, it’s best to avoid certain oils if you’re pregnant. Those include wormwood, rue, oak moss, Lavandula stoechas, camphor, parsley seed, sage, and hyssop. Ask your doctor if you’re unsure.