Adding that expensive scented oil to your bath may help your mood, but it won't do much for your health, an upcoming study has found.
Health and beauty companies have made millions off the soothing scents of aromatherapy products.
But like many home remedies, there is no hard science to prove that these smells do any real good.
A group of researchers at Ohio State University decided to test the supposed stress-relieving and healing properties of two of the most popular aromatherapy scents: lavender and lemon.
"We all know that the placebo effect can have a very strong impact on a person's health but beyond that, we wanted to see if these aromatic essential oils actually improved human health in some measurable way," said lead author Janice Kiecolt-Glaser, psychiatry and psychology professor at Ohio State University.
A series of experiments found there were none. And in some cases, distilled water showed even more of an effect than lavender.
"The take home message is that good smells may make you feel better, but you should not count on them to change your physiology," Kiecolt-Glaser said in an email.
To test the impact of the smells, researchers taped cotton balls laced with essential oils and distilled water to the nostrils of 56 healthy male and female volunteers while they underwent a series of tests over three half-day sessions.
To see if the smells could help manage pain responses they dunked the subject's feet in ice cold water.
To see if it would improve healing, they performed a standard test where tape is applied and removed repeatedly on the same spot of skin.
To test the impact on their mood, they were asked to complete three standard psychological tests during each session.
To test the impact on stress levels, they also took period blood tests and monitored their blood pressure and heart rates.
Each participant was tested in advance to make sure that each had a normal sense of smell.
Neither the lemon nor lavender oil showed any positive effect on the immune system or on the body's ability to mitigate pain or stress.
But the lemon oil showed a clear mood enhancement, according to the study, which will be published next month in the journal Psychoneuroendocrinology.
"This is probably the most comprehensive study ever done in this area, but the human body is infinitely complex," said co-author William Malarkey, a professor of internal medicine.
"If an individual patient uses these oils and feels better, there's no way we can prove it doesn't improve that person's health," he said.
"But we still failed to find any quantitative indication that these oils provide any physiological effect for people in general."