Because essential oils are so strong, Dr Lin recommends being mindful about why and how you’re using them. Only small doses are required. “It’s also a good idea not to use them routinely, as your body can get used to them, lowering their effectiveness,” she says.

There are three ways you can use essential oils:

1. Aromatherapy

Aromatherapy involves smelling essential oils to improve health. “It’s a great way to change your mood quickly. As you breathe in, the oil’s aroma immediately stimulates your central nervous system, triggering an emotional response,” explains Dr. Lin. “It can reduce anxiety and stress response quickly.”

There are several aromatherapy methods. “Whichever method you choose, avoid direct contact with the essential oil and dilute it first,” says Dr. Lin.

Aromatherapy methods include:

• The old-fashioned way: Take deep breaths of the aroma after opening the bottle.
• Diffuser method: Mix essential oils and water in an essential oil diffuser and turn on the magic. A diffuser is a device that disperses tiny oil particles around the room so you can breathe them in. Follow your diffuser’s directions for the right oil-to-water ratio.
• Dry evaporation: Put a few drops of essential oil on a cotton ball and smell the aroma as it disperses.
• Steam inhalation: Put a few drops of essential oil in a bowl of hot water. Put your head over the bowl, a towel over your head and breathe in the steam.

One caveat is that aromatherapy may not work as well for older adults with dementia or behavior problems, she notes. That may be because people tend to experience loss of smell as they get older.

2. Ingestion

Some people take essential oils orally in teas, supplements or even via a drop or two on their tongue. “Unless you’re directed by a trained herbalist, I recommend against using them this way. Since they’re so strong, they may be harmful,” advises Dr. Lin. “Even with just a few drops of essential oil, you’re taking a lot of plant material without realizing it. They can even burn the mucosal lining in your mouth.”

3. Topical application

You can also reap the benefits by applying essential oils to your skin, where it’s absorbed into your body. But Dr. Lin cautions against directly applying essential oils to your skin without diluting them. “With few exceptions, it’s best to dilute the essential oil with a carrier oil, such as coconut or jojoba oil, to avoid skin irritation,” she says.

Some people put their essential oil blend into a small rollerball bottle for easier application.

source: https://health.clevelandclinic.org/essential-oils-101-do-they-work-how-do-you-use-them/