Research by Oil: Evidence Snapshot Table
A plain table of how much PubMed research exists for lavender, peppermint, tea tree, eucalyptus, rosemary and frankincense, beside what the reviews we read actually concluded.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read essential oil safety before you use anything on this page.
How to use this page. The snapshot below counts PubMed records for six oils and two general terms. A bigger number means more has been published. It does not mean the oil works, and it does not rank the oils. The second table shows what reviews we could read said about each one. Nothing here is advice to use any oil, and no essential oil should be swallowed.
Snapshot: PubMed record counts
The counts come from PubMed searches run for this site on 2026-10-22 through the NCBI E-utilities. [1] The searches match words in the title or abstract, so they include plants, extracts, perfumery, lab work and non-human research. Eucalyptus, for example, also matches the tree and its ecology. The lavender, rosemary and frankincense searches also match the plant (Lavandula, rosemary, Boswellia) and not only the oil. [1]
| Oil or topic | Records tagged as randomized controlled trials | Records tagged as any clinical trial | All PubMed records that mention it | Check it yourself |
|---|---|---|---|---|
| Tea tree oil (Melaleuca) | 62 | 82 | 1,540 | PubMed search |
| Peppermint oil | 69 | 82 | 1,596 | PubMed search |
| Lavender | 289 | 330 | 3,029 | PubMed search |
| Eucalyptus | 44 | 64 | 6,881 | PubMed search |
| Rosemary | 75 | 89 | 3,635 | PubMed search |
| Frankincense / Boswellia | 87 | 101 | 1,358 | PubMed search |
| Aromatherapy | 381 | 435 | 2,300 | PubMed search |
| Essential oils (all) | 535 | 637 | 31,824 | PubMed search |
Counted 2026-10-22 using NCBI E-utilities. Counts include studies of extracts, blends and non-health topics, and a trial can find no effect. A higher count means more human research has been indexed, not that something works.
What the reviews we read concluded, by oil
Plant names were checked against GBIF on 2026-10-23. [2]
| Oil and plant | What a source we read found | Evidence label | Population, form and route |
|---|---|---|---|
| Lavender (Lavandula angustifolia Mill.) | NIH says it is unclear whether lavender aromatherapy helps anxiety, stress, depression, some types of pain or sleep. [3] A meta-analysis of 65 RCTs reported lower anxiety scores with inhaled lavender but flagged a high risk of bias. [4] | Promising but limited | Mixed groups; inhaled, massage and an oral lavender oil preparation are separate questions |
| Peppermint (Mentha × piperita L.) | Enteric-coated peppermint oil capsules were better than placebo for global IBS symptoms and abdominal pain in 10 RCTs (1,030 people), with more adverse events and very low certainty. [5] Inhaled peppermint did not show an effect on nausea severity after surgery. [6] | Promising but limited (IBS capsules); insufficient evidence (other uses) | Adults with IBS; oral capsules tested in trials |
| Tea tree (Melaleuca alternifolia (Maiden & Betche) Cheel) | A review of 46 RCTs found more evidence is needed for acne; research quality poor to modest. [7] NIH says a small amount of evidence suggests help for acne and athlete's foot. [8] | Promising but limited | Mouthrinse, gel and skin products; not swallowed |
| Eucalyptus (species not stated in the review below, which says only "eucalyptus oil"; Eucalyptus globulus Labill. is an accepted species name) | A systematic review with 3 trials in allergic rhinitis reported lower symptom scores; route and product were not stated in the abstract we read. [9] | Insufficient evidence (very few trials) | People with allergic rhinitis |
| Rosemary (Salvia rosmarinus Spenn.; also written Rosmarinus officinalis) | One randomized trial of 144 healthy adults found rosemary aroma linked to better memory quality but slower memory speed than no odor. [10] We did not find a systematic review of rosemary oil in people. | Insufficient evidence | Healthy adults; inhaled in a cubicle |
| Frankincense (Boswellia sacra Flück. is one named source species) | Proper evidence not found. We searched PubMed on 2026-10-23 for frankincense or Boswellia essential oil aromatherapy trials and systematic reviews and did not find a review of frankincense oil that we could read. | Proper evidence not found | None |
| Aromatherapy in general | Overview of 10 systematic reviews: for none of the conditions was the evidence convincing. [11] | Insufficient evidence | Varied |
The Cochrane reviews we read were not specific to one oil: dementia aromatherapy used lavender in eight of 13 trials and lemon balm in four. [12]
Frequently asked questions
Which essential oil has the most research?
The snapshot lists PubMed counts for each oil, but a count is not a measure of benefit. It includes plant studies and lab work. [1]
Does a high count mean an oil works?
No. A count shows how much has been published, not whether it works. [1]
Is there good research on frankincense oil?
We did not find a review of frankincense oil that we could read. Proper evidence not found for the oil itself, after searching PubMed on 2026-10-23.
Why is the evidence for peppermint oil different from lavender?
They are different questions. The peppermint evidence is mainly for oral capsules in IBS, and the lavender evidence is mainly for inhaled scent and an oral lavender preparation. [14] [3]
Is it safe to try an oil because a study found a benefit?
A study result does not make a product safe for you. Ask a pharmacist or clinician, especially for children, pregnancy, medicines or surgery. NIH advises talking with your health care providers about any complementary approach. [14]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Limits of this table
- Absent is not the same as unsafe or useless. The table shows what we could read. Other reviews may exist.
- One product is not another. Results for a capsule, a mouthrinse or inhaled scent do not carry over to a different form.
- Composition varies, even within one species, so a trial of one oil product may not match another bottle. [13]
- The snapshot is a point in time. Counts change daily.
Safety and who should ask a clinician
The oils in this table are not safe for everyone. Tea tree oil should not be swallowed; taken by mouth it can cause confusion, unsteadiness and coma. [8] Menthol should not be inhaled by or applied to the face of an infant or small child. [14] For lavender, NIH says there are theoretical reasons to suspect interactions with some sedative drugs or herbs, which matters before surgery. [3] If someone has swallowed an essential oil, call Poison Help at 1-800-222-1222 (US), or 911 for collapse, a seizure or trouble breathing. Ask a pharmacist or clinician about medicines, pregnancy and children. See medicine interactions and essential oil safety.
Individual guides: Lavender oil, Peppermint oil, Tea tree oil, Eucalyptus oil, Rosemary oil, Frankincense oil and the overview in Essential oil research and evidence.
References
- This site's PubMed record counts, run 2026-10-22 through NCBI E-utilities (file pubmedcountsessential_oils.json); the searches match words in the title or abstract. Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy species match service. Queried 2026-10-23 for Salvia rosmarinus, Rosmarinus officinalis (synonym), Boswellia sacra, Mentha x piperita, Lavandula angustifolia, Melaleuca alternifolia and Eucalyptus globulus. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Lavender: Usefulness and Safety. Page last updated February 2025. Read 2026-10-23.
- Donelli D, Antonelli M, Bellinazzi C, Gensini GF, Firenzuoli F. Effects of lavender on anxiety: a systematic review and meta-analysis. Phytomedicine. 2019;65:153099 (abstract read). Read 2026-10-23.
- Ingrosso MR, Ianiro G, Nee J, et al. Systematic review and meta-analysis: efficacy of peppermint oil in irritable bowel syndrome. Aliment Pharmacol Ther. 2022;56(6):932-941 (abstract read). Read 2026-10-23.
- Hines S, Steels E, Chang A, Gibbons K. Aromatherapy for treatment of postoperative nausea and vomiting. Cochrane Database Syst Rev. 2018;3:CD007598 (abstract read). Read 2026-10-23.
- Kairey L, Agnew T, Bowles EJ, et al. Efficacy and safety of Melaleuca alternifolia (tea tree) oil for human health: a systematic review of randomized controlled trials. Front Pharmacol. 2023;14:1116077 (abstract read). Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Tea Tree Oil: Usefulness and Safety. Page last updated April 2025. Read 2026-10-23.
- Hamayal M, Shahid W, Akhtar CH, et al. Effect of eucalyptus oil on symptoms of allergic rhinitis: a systematic review. Indian J Otolaryngol Head Neck Surg. 2025;77(2):967-974 (abstract read). Read 2026-10-23.
- Moss M, Cook J, Wesnes K, Duckett P. Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. Int J Neurosci. 2003;113(1):15-38 (abstract read). Read 2026-10-23.
- Lee MS, Choi J, Posadzki P, Ernst E. Aromatherapy for health care: an overview of systematic reviews. Maturitas. 2012;71(3):257-260 (abstract read). Read 2026-10-23.
- Ball EL, Owen-Booth B, Gray A, et al. Aromatherapy for dementia. Cochrane Database Syst Rev. 2020;8:CD003150 (abstract read). Read 2026-10-23.
- National Institute of Environmental Health Sciences (NIH). Essential Oils. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Peppermint Oil: Usefulness and Safety. Page last updated May 2025. Read 2026-10-23.