A Tennessee poison center is reporting a marked increase in children being poisoned by toxic exposure to essential oils.

According to KAKE.com, the report found that between 2011 and 2015, reports of toxic exposure to essential oils such as tea tree oil have doubled. Even more alarming is that four out of every five cases were in children.

The oils, which are derived from plants and used in aromatherapy and homeopathic products, can be harmful if consumed and even if just rubbed on the skin.

“The rule of thumb in toxicology is ‘the dose makes the poison,’ so all essential oils are potentially harmful,” said Dr. Justin Loden, a certified specialist at Vanderbilt University Medical Center’s Tennessee Poison Center.

“In children, poisoning typically occurs when they try to swallow the oil, but choke so that a little of it goes into the lungs, which causes pneumonia; it only takes less than half a teaspoonful to do that. This hazard applies to every essential oil,” Loden said in a university news release.

Excessive or inappropriate application of essential oils to the skin can also poison children because their skin is thinner than adults and can absorb dangerous amounts of these oils.

Researchers cited camphor, clove, lavender, eucalyptus, thyme, tea tree, and wintergreen oils as the most toxic essential oils.

Symptoms of poisoning can include agitation, hallucinations and seizures as well as chemical burns, breathing problems, liver failure and brain swelling.

Tea tree oil is by far the most commonly cited and most cases were accidental ingestion by children, Dr. Loden said.

The Tennessee Poison Center is offering the following tips for safe use of essential oils:

• Safely storing essential oils is extremely important

•  Use essential oil products ONLY for their intended purpose.

• Use only the amount stated on the label/guide.

• Do not swallow an essential oil unless the label says to do so.

• Do not use a product on the skin unless the label says to do so.

• Do not leave the product out (i.e. as a pesticide) unless the label says to do so.

• If you have bottles of essential oils at home, keep them locked up, out of sight and reach of children and pets at all times. Children act fast, so do poisons.