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Castor Oil in Hair Products: What the Research Shows

Writer: Maggie. R
Maggie. R
12 minutes ago
4 min read

Castor oil is a thick, pale vegetable oil pressed from castor seeds, and about 90 percent of it is a single fatty acid, ricinoleic acid. In hair care it acts as a heavy, film-forming conditioning oil. What it has not been shown to do is make hair grow: a Cleveland Clinic physician says there is no data showing that pure castor oil applied to hair promotes growth.



What castor oil is and where it comes from


Castor oil is pressed from the seeds of Ricinus communis, a plant grown mainly in Africa, South America and India. A 2016 review in Lipid Insights reports that India accounts for more than 90 percent of castor oil exports, and that the oil is up to about 90 percent ricinoleic acid, with small amounts of linoleic, oleic and stearic acids.

On an ingredient list it appears as Ricinus communis (castor) seed oil. The reference site CosmeticsInfo.org describes it as an occlusive skin-conditioning ingredient, a term for ingredients that form a protective layer on the surface.

Castor beans contain ricin, a toxic protein, along with allergenic proteins. The Lipid Insights review states that processed or refined castor oil is free of them, and CosmeticsInfo.org notes that ricin does not dissolve into the oil.



How castor oil is made, and what cold-pressed means


The Lipid Insights review describes three ways to extract the oil: mechanical pressing, solvent extraction, or a combination. It reports that cold-pressed castor oil has lower acid and iodine content and a lighter color than solvent-extracted oil. Refining steps such as degumming, neutralization, bleaching and deodorization are then used to clean up the crude oil's color and odor.

That review is about production, not hair. It does not test whether an extraction method changes how the oil performs on hair, so a term like cold-pressed on a label describes how the oil was made, not a result you can expect.



Why it appears on hair and skin labels


Castor oil is thick, so it is used to coat and condition. Several related ingredients are made from it, and CosmeticsInfo.org lists their roles. Look for these names on a label:

  • Ricinus communis (castor) seed oil: the oil itself, used as an occlusive skin-conditioning ingredient.

  • Hydrogenated castor oil: used as an occlusive and as a viscosity-increasing agent in non-water-based formulas.

  • Glyceryl ricinoleate: used as an emollient and an emulsifier.

  • Sodium ricinoleate: used as a cleansing and emulsifying agent.

  • Ricinoleic acid: the main fatty acid of castor oil, also listed as a cleansing agent.

Safety and benefit are separate questions. The Cosmetic Ingredient Review Expert Panel concluded that castor oil and its derivatives are safe as cosmetic ingredients, according to CosmeticsInfo.org. That is a safety finding, not a finding that the oil changes how hair grows. Cleveland Clinic adds that the FDA has approved castor oil as a laxative for temporary constipation, which it calls the oil's only legitimate health-related use.

Castor oil is rarely used alone. As one example of a finished blend, the Crown Care Scalp & Haircare Therapy Oil lists castor oil among its plant oils on its product page. We mention it as an example of a formula, not as evidence that castor oil affects hair growth.

Crown Care Scalp & Haircare Therapy Oil
$39.99
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What the research shows about castor oil and hair


Direct evidence is thin. Cleveland Clinic physician Kevin Hopkins, MD, says there is no data showing that applying pure castor oil to hair promotes growth, and the article adds that most popular claims about faster hair growth do not hold up.

The wider research on oils and hair is also limited. A 2015 review in the International Journal of Trichology notes that few articles have studied mineral and vegetable oils on human hair. In one study it describes, coconut oil reduced protein loss from hair, while sunflower and mineral oil did not, although those two may leave a film that adds shine and reduces friction. Castor oil was not among the oils in that study, so it is not evidence for or against castor oil.

That review also makes a point worth keeping in mind when you read labels: how ingredients interact inside a formula can matter more than any single ingredient, whatever the marketing suggests.

What a heavy oil can change is appearance. A thick film can mask lifted cuticle scales, but the review cautions that it can also leave hair looking oily and heavy, and it favors oils that leave a thin layer.



Cautions with heavy oils


Cleveland Clinic lists several risks of putting pure castor oil on hair and skin:

  • Irritation, clogged pores and scalp acne when it is applied to the hair and scalp.

  • Irritation and allergic reactions, including contact dermatitis, when pure castor oil is applied to skin.

  • In rare cases, acute hair felting, a scalp disorder in which hair becomes hard, tangled and matted and has to be cut off or shaved.

Gentle handling matters too. The Trichology review recommends gentle shampooing, towel drying, brushing and combing, and it links tangles created by combing forces to breakage. If you are looking for a detangling tool, the Crown Care Detangling Hair Brush is one option in our shop. It is a styling tool, not a treatment.

Crown Care Detangling Hair Brush
$29.99
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If you notice significant hair loss or thinning, Cleveland Clinic advises seeing a doctor to rule out illness or nutrient deficiencies. A dermatologist can diagnose the cause of a scalp or hair concern; an oil cannot.



Sources


This article is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any condition. Talk with a qualified healthcare provider about skin or scalp concerns.

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