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Zinc salt of ricinoleic acid (castor)

Zinc ricinoleate

Zinc ricinoleate is a zinc salt of the main fatty acid in castor oil that is used in deodorants to bind odour molecules rather than to stop sweat or kill bacteria. The Cosmetic Ingredient Review panel judged it safe in cosmetics as currently used, but we found no trial of it in underarm deodorants, so the odour claim rests on chemistry and one industry-funded lab test.

The one caution is allergy: there are case reports of allergic contact dermatitis from deodorants containing it.

Updated
10 October 2026
A plain deodorant stick beside castor beans
At a glance
Last reviewed 10 October 2026
Evidence
Traditional
Best for
Underarm odour control
Typical form & use
Deodorant spray or stick, up to 2.3%
Onset
Same night
Safety
Can cause contact allergy in some users. No interactions in our data.
Check with your medications →

What it's used for

Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.

UseEvidenceWhat the research shows
Underarm odour control (deodorant)Compare remedies for skin →Traditional

A 2024 chemistry paper says zinc ricinoleate can chemically bond with sulfur- and nitrogen-containing compounds, which is why it is used to adsorb odours, and describes zinc oxide-based materials as good at removing odour-producing compounds. That is a description of how it works, not a test on armpits: we found no human trial of it in an underarm deodorant.

Antiperspirants work differently, by forming a plug of aluminium salts in the sweat pore, whereas deodorants target the odour, usually by limiting the bacteria that make it. We rate this 1: a plausible mechanism and wide use, with no clinical trial found.3,5,6

Odour control in ostomy pouches (simulated)Traditional

In a 2024 simulated test, eleven trained odour assessors rated pouches containing a synthetic faecal odour (skatole) with six different additives. Plain zinc ricinoleate sat in the group rated 2.7 to 3.0 for odour intensity on a 0 to 6 scale, against 3.7 for the untreated control.

The product with orange terpenes added scored 0.9, but the paper notes scented products differed in character and does not show the zinc salt was responsible. The study was run by a lab and funded by Convatec, which makes a competing additive (the best performer), and used assessors rather than people with stomas. Limited and indirect, so rated 1.4

Skin and aerosol safety in cosmetics (regulatory view)Limited

Not a remedy but the reason many readers search. A 2007 Cosmetic Ingredient Review assessment of castor-oil-derived ingredients, which included zinc ricinoleate, concluded they are safe in the practices of use and concentrations described, and that zinc ricinoleate was not a sensitiser in guinea pigs.

A 2018 review of 27 zinc salts reached the same conclusion for zinc ricinoleate when formulated to be non-irritating, noting it is used in deodorant aerosols up to 2.3% and pump sprays up to 0.82%. The animal data were mostly undiluted tests in rabbits.

The human evidence is case reports of allergic contact dermatitis to zinc ricinoleate in deodorants. Rated 2 because the regulatory view rests largely on animal tests.1,2,7,8,9

How much

Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.

Reported use in deodorant aerosols
Up to 2.3%2
The highest concentration the Cosmetic Ingredient Review listed for zinc ricinoleate, in deodorant aerosol sprays. Pump sprays were reported up to 0.82%. We found no source on the concentration that works.
Acute oral toxicity (rats)
LD50 above 2,000 mg/kg2
A test in rats, listed in the 2018 review as above 2,000 mg/kg (over 198 mg/kg as free zinc). This is a toxicology figure, not an intake recommendation, and zinc ricinoleate is not meant to be swallowed.
Timing · We found no source on how often or when to apply a zinc ricinoleate deodorant, so follow the product label.With food? · Not applicable: it is applied to skin and is not a food or supplement.How long to trial · No underarm trial timeline exists. Deodorant effects on odour would be noticed within a day of use, but that is our inference, not from a source.

How people take it

Deodorant spray (aerosol or pump)Up to 2.3% (aerosol), 0.82% (pump)The Cosmetic Ingredient Review found 95% to 99% of droplets from cosmetic sprays are too large to reach the lungs and saw no inhalation concern.
Stick, cream or roll-on deodorantVaries by productOften sold as aluminium-free or 'natural'. We found no concentration data for these forms.
Odour-control additive (ostomy, household)Varies by productZinc ricinoleate is also used to capture odours in products other than deodorant. Evidence is limited to the ostomy test above.

Safety

Who should avoid
  • Previous contact allergy to a deodorant — case reports link zinc ricinoleate to rashes
  • Broken or shaved-and-irritated skin — tests found irritation of abraded skin with a zinc ricinoleate mixture
  • Sensitive skin reactions to ricinoleates — people with some skin conditions have reacted to ricinoleic acid
Known interactions
No interactions in our data. Absence of a flag is not clearance.

Questions people ask

How does zinc ricinoleate work as a deodorant?

It binds odour molecules rather than blocking sweat. A 2024 chemistry paper says it can chemically bond with sulfur- and nitrogen-containing compounds, which is why it is used as an indoor-air odour adsorbent.

It is not an antiperspirant: those use aluminium salts to plug sweat pores, and a review describes deodorants as mainly targeting the odour-forming bacteria.

Is zinc ricinoleate safe?

The Cosmetic Ingredient Review panel judged it safe in cosmetics as currently used (up to 2.3% in deodorant aerosols) when formulated to be non-irritating, and animal tests found it was not a sensitiser.

Even so, there are case reports of allergic contact dermatitis to zinc ricinoleate in deodorants, so stop using a product that makes your underarms itchy or red.

Does zinc ricinoleate come from castor oil, and is it natural?

It is made from ricinoleic acid, which makes up about 90% of castor oil's fatty acids, reacted with zinc. A 2024 paper describes making it by converting castor oil to methyl ricinoleate and then reacting that with zinc oxide.

Whether that counts as natural is a labelling choice rather than a safety finding; one allergy case report involved a deodorant sold as natural. See our castor oil entry for the oil itself.

Is zinc ricinoleate effective in natural deodorants?

We could not find a trial. The mechanism is plausible and it is widely used, but the only performance test we opened was a simulated ostomy pouch study funded by a competitor, where the plain zinc product gave a modest drop in odour score. Aluminium-free deodorants in general do not stop sweat, only manage odour.

Sources (9)

  1. Safety assessment Final report on the safety assessment of Ricinus Communis (Castor) Seed Oil, Hydrogenated Castor Oil, Glyceryl Ricinoleate, Glyceryl Ricinoleate SE, Ricinoleic Acid, Potassium Ricinoleate, Sodium Ricinoleate, Zinc Ricinoleate, Cetyl Ricinoleate, Ethyl Ricinoleate, Glycol Ricinoleate, Isopropyl Ricinoleate, Methyl Ricinoleate, and Octyldodecyl Ricinoleate. Int J Toxicol. 2007.
  2. Safety assessment Cosmetic Ingredient Review. Safety Assessment of Zinc Salts as Used in Cosmetics (final report). 2018.
  3. Laboratory study Cohen S, Chajanovsky I, Suckeveriene RY. Novel Preparation and Characterization of Zinc Ricinoleate Through Alkali Catalysis. Polymers (Basel). 2024.
  4. Laboratory odour assessment Meacham A, Gowans P, Bradley-Clarke J, Swearingen A, Lord S. Effectiveness of Malodor-Reducing Ostomy Pouch Additives: An Assessment of Odor Intensity, Hedonic Tone, and Odor Character. Cureus. 2024.
  5. Systematic review Teerasumran P, Velliou E, Bai S, Cai Q. Deodorants and antiperspirants: New trends in their active agents and testing methods. Int J Cosmet Sci. 2023.
  6. Review Oliveira ECV, Salvador DS, Holsback V, Shultz JD, Michniak-Kohn BB, Leonardi GR. Deodorants and antiperspirants: identification of new strategies and perspectives to prevent and control malodor and sweat of the body. Int J Dermatol. 2021.
  7. Case report Samaran Q, Dereure O, Raison-Peyron N. Allergic contact dermatitis to zinc ricinoleate in a 'natural' deodorant. Contact Dermatitis. 2024.
  8. Case report Magerl A, Heiss R, Frosch PJ. Allergic contact dermatitis from zinc ricinoleate in a deodorant and glyceryl ricinoleate in a lipstick. Contact Dermatitis. 2001.
  9. Case report Badaoui A. Allergic Contact Dermatitis to Zinc Ricinoleate in a Deodorant. Contact Dermatitis. 2026.

Reader notes

Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.

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Last reviewed 10 October 2026 · Next review April 2027 · How we rate evidence