Peppermint oil scent could help relieve pain after heart surgery

Some studies indicate that aromatherapy could effectively reduce postoperative pain. For example, one study found that aromatherapy with peppermint oil can reduce pain linked to intravenous catheterization — when a long, thin, and flexible tube called a catheter is put in a vessel in areas of the body such as the arm or neck.

Studies also show that peppermint oil may improve the sleep quality of cardiac patients, which may, in turn, aid recovery following surgery.

Further study of how aromatherapy with peppermint oil affects patients following cardiac surgery could aid the development of pain treatments.

Recently, researchers published the results of a double-blind, randomized clinical trial to investigate the effects of peppermint oil aromatherapy on pain ratings and sleep quality following cardiac surgery. They found that aromatherapy both reduced pain and improved sleep quality after open-heart surgery.

They have published their findings in BMJ Supportive & Palliative Care.

For the study, the researchers recruited 64 patients with an average age of 61 years who underwent open-heart surgery.

Heart bypass surgery was the most commonly performed. It involves removing a section of a blood vessel from another part of the body and then grafting it into the heart to reroute blood around a blocked artery.

The researchers split the patients into two groups. While one group received 0.1 milliliters (ml) of 10% essential peppermint oil aromatherapy plus 10mL distilled water, the other received a placebo consisting of 10 ml of distilled water.

Both treatments were administered 30 minutes before patients’ breathing tubes were removed following surgery, and then three times daily via a nebulizer for another 2 days. Patients received 7 doses in total.

The researchers used the Numeric Pain Rating Scale and the St. Mary’s Hospital Sleep Questionnaire to assess changes in pain severity and sleep quality.

Ultimately, they found that patients in the aromatherapy group experienced significantly less pain than those in the placebo group. Patients who received aromatherapy had an average pain score of 3.22, whereas those on the placebo had a pain score of 4.56.

The aromatherapy group also had significantly better sleep quality scores than those given placebo. On day one, the aromatherapy and comparison group had sleep scores of 20.1 and 25.76, respectively, which fell to 18.63 and 22.62, respectively, by day two. Lower scores indicate better sleep quality.

The researchers further noted that those who received peppermint oil aromatherapy required fewer pain relief medications than patients in the placebo group.

The researchers concluded that their findings show that peppermint aromatherapy can reduce pain intensity following open-heart surgery and improve sleep quality.

“Considering the effect of peppermint essential oil inhalation on pain and sleep quality of patients after open-heart surgery, it can be concluded that this herbal product can be safely used as a complementary treatment in relieving pain and making patients comfortable after heart surgery,” the authors write in the study paper.

During aromatherapy, inhaled particles are absorbed through the nasal mucosa and the lungs. Research indicates that as soon as peppermint aroma is inhaled, its molecules become present in the blood and then in the brain and nervous system, from where they produce physiological and behavioral changes.

How exactly peppermint oil relieves pain remains unknown. However, the researchers noted the constituents of the oil, including menthol, carvone, and limonene, may play a role. They added that peppermint is known for its anti-spasm, analgesic, anti-inflammatory, anti-congestion, and antioxidant properties.

Dr. J. Wes Ulm, a bioinformatic scientific resource analyst, and biomedical data specialist at the National Institutes of Health, who was not involved in the study, told Medical News Today:

“Peppermint oil is actually one of the oldest folk remedies known to societies, dating back to at least ancient Greece, when it was mentioned in several relevant texts. Evidence for its efficacy in treating modern ailments is mixed and remains unclear; however, there have been some indications that it may be of assistance in the management of, for example, tension, headaches, and irritable bowel syndrome [IBS]. It may also be helpful [in easing nausea and vomiting], particularly in certain cohorts of patients, such as those who are post-op or hospitalized.”

“The actual administration of the peppermint oil varies in each of these cases, for example, applied topically for headaches or localized pain, or provided as a dietary assist for conditions like indigestion and IBS,“ he added.

“The anti-nausea effects have been the primary province of peppermint oils when used as an aromatherapy, but the study suggests that this route of administration may also be valuable in exerting the oils’ analgesic effects and in aiding better quality sleep,” Dr. Ulm explained.

Dr. Ulm said that the findings are limited due to the study’s small sample size. He added that although patients were not told whether they were in the aromatherapy or peppermint group, they likely figured it out as the placebo was water-based. This, he noted, could have introduced bias into the results.

He noted that if the study’s findings are supported by further research, the aromatherapy may be used in post-operative scenarios as a relatively low-cost, easy-to-administer analgesic with sleep-enhancing effects.

“Although the mechanism of peppermint oil’s putative pain-relieving action remains unclear, it may turn out to have properties similar to that of capsaicin, a key ingredient of chili peppers also found to be useful as an analgesic. More studies are needed to confirm this, however,” he concluded.