Cypress Oil: Evidence, Safety and How It Is Used
Cypress oil (Cupressus sempervirens): mostly laboratory research, no good human trials found, and why hinoki cypress studies are about a different tree. Safety gaps stated plainly.
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.
Safety note: the sources we read give little safety information for cypress oil itself, and lack of information is not proof of safety. Do not swallow essential oils; if anyone does, call Poison Help at 1-800-222-1222 (US), and call 911 for collapse, a seizure or trouble breathing.
What cypress oil is
Cypress oil usually refers to the essential oil of the Mediterranean cypress, Cupressus sempervirens L., in the cypress family (Cupressaceae). [1] The studies we found describe oil obtained from the leaf. [2] In the oil analyzed in two laboratory papers, the main components were the monoterpenes alpha-pinene and delta-3-carene. [2][3] Composition differs between samples, so a result for one oil does not describe all products.Names that cause mix-ups
| Name | Plant | Why it matters |
|---|---|---|
| Cypress oil | Cupressus sempervirens L. [1] | The subject of this page |
| Hinoki cypress | Chamaecyparis obtusa (Siebold & Zucc.) Endl., a different genus in the same family [1] | Human studies exist for this tree, but they do not transfer to Cupressus |
| "Cedar" woods | Many unrelated trees, including some in Cupressus and Juniperus [4] | See cedarwood oil |
Check the botanical name on a label (reading a label).
Traditional use
The sources we read do not describe traditional uses of cypress oil, so we describe none and do not treat tradition as proof.What research shows
| Question | What the source found | Strength of evidence | Population and form studied |
|---|---|---|---|
| Does Cupressus sempervirens oil help any health problem in people? | Proper evidence not found. We searched PubMed for Cupressus sempervirens essential oil, cypress oil and human trials. The results were laboratory studies of germs, antioxidants and insects, plus unrelated pollen-allergy studies, with no trial of the oil in people. | Insufficient evidence | Not applicable |
| Effect on cells and germs | One study tested antioxidant, antimicrobial, insecticidal and anti-cancer-cell activity; the oil showed no effect on a normal lung cell line but did affect several cancer cell lines. [2] | Preclinical (cells) | Laboratory |
| Toxicity in animals | A 2022 study tested the oil on zebrafish embryos and reported concentration-dependent lethality, with an LC50 (the concentration that killed half) of about 6.6 micrograms per mL. It also used computer predictions that many of the oil's components had no toxic effects. [3] This is a laboratory toxicity signal, not a judgment that the oil is safe or unsafe for people. | Preclinical (animals); not transferable to people | Zebrafish embryos |
| Relaxation, swallowing (hinoki cypress) | A small study of 13 female students and a randomized crossover study of 34 older adults with swallowing difficulty tested inhaled hinoki cypress oil. [5][6] | Promising but limited, for a different tree | Young women; older adults with dysphagia |
The older-adult trial compared hinoki cypress oil with a rice-oil placebo in a placebo-controlled, single-blind, randomized crossover design. [6] Its authors say the findings warrant confirmation in larger and longer trials. [6] The earlier study notes there were no previous studies of the physiological effects of smelling hinoki cypress leaves. [5] Neither used Cupressus sempervirens. Smell-based trials are hard to blind and many measure self-reported feelings. A dish result is not an effect in people (human vs lab research).
Popular marketing claims for cypress oil are not backed by any human trial we found. The FDA says claims that a product will, for example, ease pain or relax muscles are drug claims. [7]
Forms, and why the form matters
The laboratory work used leaf oil. [2] The hinoki studies used inhaled oil for a short time. [5][6] We give no amounts or dilutions.Safety
- What is not documented. The sources we read do not describe interactions with medicines, pregnancy and breastfeeding, children, older adults (beyond the hinoki trial population), liver and kidney conditions, asthma, or skin allergy for Cupressus sempervirens oil. Absence of data is not proof of safety. Ask a pharmacist (how interactions work).
- General oil cautions. The FDA says many plants contain materials that are toxic, irritating, or likely to cause allergic reactions when applied to the skin. [7] See skin reactions and allergy and patch testing.
- Children and pets. Keep essential oils locked up, out of the sight and reach of children and pets. [8] Pet Poison Helpline lists cypress among essential oils that can cause poisoning in pets, and says cats and birds are at greatest risk. [9] Its page covers essential oils in general and does not give a dose for cypress oil.
- Surgery: tell the surgical team about any oil product.
Quality and adulteration
The sources we read do not describe adulteration of cypress oil specifically. For general information see essential oil purity and adulteration.Official statements
No regulator monograph for cypress oil is described in the sources we read.Uses studied and safety checks for Cypress Oil
Read the safety checks first. Each card says whether a finding comes from people or only from the lab, which way the oil was used (scent, on skin or swallowed) and how strong the evidence is. A finding for one way of using an oil does not carry over to another.
Check before you use (3)
- Skin reactions (general caution). The FDA says plant-derived fragrance materials can be toxic, irritating or allergenic on skin. Poison Control says rashes are the most common reaction to essential oils. The sources we read describe no skin testing of cypress oil itself.
- Cats, dogs and birds. Pet Poison Helpline lists cypress among essential oils that can cause poisoning in pets, and says cats and birds are at greatest risk, with strong concentrations of more concern than weak products.
- Swallowing and children. Poison Control says swallowing essential oils can be dangerous and that oils should be kept out of the sight and reach of children and pets. It does not name cypress. If anyone swallows an oil, call a poison center (US: 1-800-222-1222) or your local emergency number.
Any health use in people (no human trials found)
Not enough evidenceWe found no trial of Cupressus sempervirens essential oil in people. Searches returned lab studies of germs, antioxidants and insects, not human research.
Supplements: Proper evidence not found in the sources we read.
Cells, germs and insects (lab only)
Lab or animal research onlyIn dishes, cypress leaf oil showed antioxidant, antibacterial, antifungal and insect-killing activity, no effect on a normal lung cell line, and effects on several cancer cell lines.
Supplements: Lab only.
Lab toxicity signal in zebrafish embryos
Lab or animal research onlyIn zebrafish embryos the oil was harmful in a concentration-dependent way (LC50 about 6.6 micrograms per mL); computer models predicted many components were not toxic.
Supplements: Lab and animal only.
Hinoki cypress scent studies (a different tree)
Not enough evidenceSmall human studies of inhaled hinoki cypress (Chamaecyparis obtusa) oil found more relaxation signs in 13 young women and better swallowing scores in 34 older adults than rice-oil placebo, in a single-blind crossover trial. They did not use Cupressus sempervirens, so they say nothing about this oil.
Supplements: Not evidence for cypress oil.
Frequently asked questions
Does cypress oil have proven health benefits?
Proper evidence not found. Our PubMed searches returned laboratory studies, not trials in people.
Is hinoki cypress oil the same as cypress oil?
No. Hinoki cypress is Chamaecyparis obtusa, a different genus from Cupressus. [1]
Did the hinoki cypress swallowing trial show it works?
It found better swallowing test scores with inhaled hinoki oil than with a rice-oil placebo in 34 older adults, and the authors call for larger, longer trials. [6]
Is cypress oil safe to swallow?
No. We do not advise swallowing any essential oil.
Is cypress oil safe in pregnancy or for children?
Not described in the sources we read. See essential oils in pregnancy and ask a clinician.
References
- GBIF species-matching service (plant names checked 2026-10-23). Read 2026-10-23.
- Biological Activity of Cupressus sempervirens Essential Oil, Plants 2023. Read 2026-10-23.
- Cupressus sempervirens Essential Oil: antibacterial mechanisms, toxicity prediction and safety assessment in zebrafish embryos, Molecules 2022. Read 2026-10-23.
- Cedarwood Oils: The Wood Essential Oil Compositions from Trees Known as "Cedar", Plants 2026. Read 2026-10-23.
- Physiological effect of olfactory stimulation by Hinoki cypress (Chamaecyparis obtusa) leaf oil, Journal of Physiological Anthropology 2015. Read 2026-10-23.
- Inhaled hinoki cypress essential oil improves saliva secretion and swallowing function in older adults with dysphagia: a randomized crossover study, 2026. Read 2026-10-23.
- US Food and Drug Administration, Aromatherapy (cosmetics information page). Read 2026-10-23.
- Poison Control (National Capital Poison Center), essential oils article. Read 2026-10-23.
- Pet Poison Helpline, Essential Oils. Read 2026-10-23.