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- Posted March 29, 2025
Citrus Oil Formula May Relieve Dry Mouth for Cancer Patients
A new formula made with natural citrus oil could help cancer patients find relief from dry mouth, a common and painful side effect of radiation treatments.
The formula was created by researchers at the University of South Australia and Stanford University. It mixes limonene -- a citrus oil found in lemons, limes and oranges -- with healthy fats known as lipids.
Mixed together, they make the oil much easier for the body to absorb and reduce common side effects like dry mouth and stomach pain.
In lab tests, the new mix was 180 times more soluble than pure limonene. In early trials, it increased absorption in the body by more than 4000%, according to a news release.
Dry mouth, or xerostomia, affects up to 70% of patients who get radiation for head and neck cancer. It can make speaking and swallowing very difficult and can lower quality of life.
“Cancer patients undergoing radiotherapy and other medical treatments regularly experience dry mouth, which not only prevents them from comfortably swallowing, but can also have other negative and potentially life-threatening outcomes,” said co-researcher Leah Wright, a professor of chemical engineering at The University of Adelaide in Australia.
Limonene has long been known to help with saliva production, but high doses were needed to work well. Those doses often caused side effects like indigestion and “citrus burps.”
Lead author Clive Prestidge, head of the Nanostructure and Drug Delivery research group at the University of South Australia, says the new formula solves that problem.
“The therapeutic benefits of limonene are well known. It’s used as an anti-inflammatory, antioxidant and mood-enhancing agent, and can also improve digestion and gut function. But despite its widespread use, its volatility and poor solubility have limited its development as an oral therapy,” Prestidge said in a news release.
Wright added that even though limonene can be ingested directly, it's not well tolerated, especially with folks who have dry mouth. "Plus, its poor absorption prevents it from effectively reaching the salivary glands -- the target site," she added.
“This inventive and highly impactful limonene-lipid 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,” Wright said.
The findings were recently published in the International Journal of Pharmaceutics.
More information
The Cleveland Clinic has more on dry mouth (xerostomia).
SOURCE: University of South Australia, news release, March 24, 2025
