Chemotherapy-Induced Nausea and Vomiting

Parsa Tabei et al. (2025) · BMC complementary medicine and therapies

This randomized controlled trial with 92 breast cancer patients explored whether breathing in the scent of bitter orange (Citrus aurantium) essential oil could ease chemotherapy-induced nausea and vomiting (CINV) — sickness that standard anti-nausea drugs don't always fully control. CINV is typically split into an acute phase (the first 24 hours after treatment, driven mainly by serotonin release) and a delayed phase (roughly 1-5 days later, governed by different chemical signals including substance P). The study tested whether a simple, inhaled essential oil could specifically help with that harder-to-treat delayed phase. Ninety-two women undergoing AC-T chemotherapy for breast cancer (average age 48) were randomly assigned to inhale either bitter orange oil or a scentless sunflower-oil placebo — two drops on the upper lip, breathed in for 20 minutes, three times a day for five days, on top of their usual anti-nausea medication. Neither the patients, their nurses, nor the researcher analyzing the results knew who received which oil. Each day, patients rated their nausea, vomiting, and retching on the Rhodes Index, a validated 0-to-35 symptom scale. For the first two days, both groups fared about the same — expected, since standard medications already cover that early window well. But from Day 3 onward, the bitter-orange group pulled clearly ahead: by Day 5, their average total symptom score was roughly half the control group's (3.6 vs 7.1 out of 35, p=0.002), with similarly meaningful drops in vomiting (p=0.01), nausea (p=0.004), and retching (p=0.02) scores specifically. Within the aromatherapy group, symptoms dropped so much from Day 1 to Day 5 that the effect size was "very large" by conventional standards (Cohen's d=1.62 for total symptoms) — the placebo group barely moved at all over the same stretch. No one in either group reported side effects or discomfort from the oils. The pattern — no early benefit, a real one later — fits with what's known about the delayed phase of CINV being harder for drugs to reach and potentially more open to complementary approaches like aromatherapy. Because the trial didn't measure symptoms before treatment started and drew only from one clinic and one cancer type, these results need confirming in larger, more varied studies before bitter-orange aromatherapy becomes a routine recommendation — but as a cheap, safe add-on alongside standard antiemetics, the early signal here is encouraging.

Jing-Yu Tan et al. (2022) · BMC complementary medicine and therapies

This preliminary randomized controlled trial with 114 breast cancer patients starting their first round of chemotherapy explored whether auricular acupressure -- pressing small seeds against specific points on the outer ear -- could ease chemotherapy-induced nausea and vomiting (CINV), a side effect that standard anti-nausea drugs do not fully control. The study is grounded in the idea, borrowed from Traditional Chinese Medicine, that stimulating certain ear points can influence nausea pathways elsewhere in the body. To find out how much of any benefit was real versus expectation, researchers compared a "true" acupressure group against a look-alike "sham" version and against standard care alone. Women scheduled for chemotherapy known to cause significant nausea were split into three groups of 38: true acupressure (firm seeds pressed on seven ear points three times a day for five days), sham acupressure (soft, non-stimulating seeds at the same points and schedule), and standard antiemetic care alone. Everyone received standard anti-nausea medication regardless of group. Nausea and vomiting were tracked using the MASCC Antiemesis Tool, a validated eight-item scale, on the second and sixth days of the chemotherapy cycle, and quality of life was measured separately. Both acupressure groups did better than standard care alone for CINV occurring in the first 24 hours (acute CINV). More than half of the true acupressure group (52.6%) had no nausea or vomiting at all in that window, compared to under a quarter (23.7%) on standard care alone (a meaningful and statistically significant difference, p=0.01). Total symptom scores were also meaningfully lower with true acupressure across several measures (p-values from 0.001 to 0.004, with effect sizes edging toward "large"). The catch: the sham acupressure group did almost as well as the true group on nearly every measure, meaning much of the benefit looks like a placebo effect rather than something unique to real acupressure -- though the researchers note that a placebo effect big enough to meaningfully reduce nausea is still clinically useful. Neither approach measurably helped with nausea that showed up later (days 2-5) or with quality of life. Practically, this suggests auricular acupressure is a safe, low-cost option worth adding alongside standard anti-nausea medication for the first day of chemotherapy, with only mild, temporary ear discomfort reported by about 1 in 7 participants. The main limitation is that the study was small and not designed to definitively prove acupressure's own mechanism works beyond expectation -- a larger, more rigorously powered trial is needed to confirm whether the benefit holds up and how much is truly attributable to acupressure itself versus the ritual of treatment.