Dry Mouth? Citrus Oil Mixture Could Help

Dry mouth — a common side effect of some breast cancer treatments — can make it hard for people to chew, taste, swallow, and speak. The longer the problem lasts, the more time mouth bacteria have to multiply, leading to cavities, mouth infections, pain, and more.

Now researchers say they’ve come up with a new combination of citrus oil and healthy fats that people may someday be able to use to find relief from dry mouth. They described the new oral formula, which is currently being tested in people, in The International Journal of Pharmaceutics.

“This inventive and highly impactful … formulation could provide a simple, effective oral solution for dry mouth, offering cancer patients long-lasting relief and comfort, improved oral health, and a higher quality of life during a difficult time,” lead author Leah Wright, PhD, said in a press release. Wright is a postdoctoral researcher at the School of Chemical Engineering at the University of Adelaide in Australia.

For a while, scientists have known that a citrus essential oil made from the peels of lemons, limes, and oranges can help with dry mouth by boosting saliva production. This citrus oil is available for purchase in the form of large liquid capsules, but people who have dry mouth often find these capsules difficult to swallow.

People also have a hard time absorbing citrus oil in its natural form, so, a person would have to take a lot of it for the oil to help with dry mouth. Taking such a high dose can cause side effects like indigestion, stomach pain, and unpleasant “citrus burps.”

In the new study, researchers found a way to make citrus oil dissolve 180 times better than it does without any scientific tinkering: by combining it with other healthy fats and oils. This makes the active ingredient of the citrus oil, limonene, 4,000% more present in the salivary glands. It’s also easy for people with dry mouth to swallow.

The researchers tested how well the body absorbs a few varieties of the citrus oil mixture using human-made replicas of stomach and intestine fluids. Then, they tested a few of the citrus oil formulations in rats to pick the one that was absorbed the best and led to the most limonene in the salivary glands.

The researchers are now testing the citrus oil formula in people, but these results are not yet available. If the results of these studies reveal the citrus oil to be as effective in people as was found in the animal tests it could mean that people with cancer would need to take only a small dose of citrus oil to treat dry mouth, reducing gastrointestinal side effects.

The citrus oil formula is not yet available for purchase.