What is castor oil? Benefits for lashes, brows, face, and skin

If you've spent any time in natural beauty circles, you've likely come across castor oil. It appears on the ingredient lists of lash serums, brow gels, lip balms, hair growth oils, and facial moisturizers — and for good reason. Unlike many trending ingredients that are backed by little more than marketing claims, castor oil has a documented history of use spanning thousands of years, a well-understood mechanism of action, and a growing body of modern research supporting its practical benefits.

This post covers everything worth knowing: what castor oil actually is, how it works on skin and hair, what the research says, how to use it correctly, and who it is — and isn't — for.

Quick summary

What it does: Deeply moisturises skin and hair, supports lash and brow fullness, helps soothe inflammation and seal the skin barrier
Best for: Dry skin, sparse lashes and brows, coarse or damaged hair, anyone wanting a clean multi-use oil
Not for: Very oily or acne-prone skin (use with caution), those sensitive to Ricinus communis
Key evidence: Ricinoleic acid, which makes up approximately 90% of castor oil's fatty acid profile, has documented anti-inflammatory and humectant properties in peer-reviewed research
Where to find it: Selfwise Organic Castor Oil Face Moisturizer and Rosemary & Multi-Oil Hair Growth Oil

What is castor oil?

Castor oil is a vegetable oil pressed from the seeds of Ricinus communis, a flowering plant native to tropical East Africa and India that is now cultivated in warm climates worldwide. The seeds — commonly called castor beans — are cold-pressed to extract a pale yellow oil with a thick, viscous consistency that distinguishes it from most other plant oils.

Its most defining characteristic is its unusually high concentration of ricinoleic acid, an 18-carbon omega-9 fatty acid that makes up approximately 85 to 95% of castor oil's total fatty acid content. This is a composition found in no other commonly available plant oil, and it is responsible for most of castor oil's documented benefits.

Castor oil at a glance

Property	Detail
INCI name	Ricinus Communis (Castor) Seed Oil
Plant source	Ricinus communis (castor bean plant)
Key fatty acid	Ricinoleic acid (85–95% of total fatty acids)
Texture	Thick, viscous — thicker than most plant oils
Colour	Pale yellow to colourless
Scent	Mild, slightly nutty — very low odour
Comedogenic rating	1 out of 5 (low) — generally non-pore-clogging
Used in Selfwise products	Organic Castor Oil Face Moisturizer, Rosemary & Multi-Oil Hair Growth Oil

How castor oil works

The majority of castor oil's benefits stem from three core mechanisms driven by ricinoleic acid.

1. Humectant and occlusive moisturisation

Ricinoleic acid is a hydroxyl fatty acid — it contains a hydroxyl group on its carbon chain that gives it humectant properties, meaning it can attract and bind water molecules to the skin surface. Unlike many oils that simply sit on top of skin, castor oil can help draw moisture into the outer layers of the epidermis while simultaneously forming a barrier that reduces transepidermal water loss.

This dual action makes it particularly effective for very dry, cracked, or compromised skin where the barrier function has been disrupted. A 2019 review in the International Journal of Molecular Sciences confirmed ricinoleic acid's role in skin barrier support and its ability to reduce inflammation in the skin's outer layers.

2. Anti-inflammatory action

Ricinoleic acid has been shown in multiple studies to inhibit prostaglandin synthesis — the same pathway targeted by common anti-inflammatory drugs. Research published in Mediators of Inflammation demonstrated that topically applied ricinoleic acid reduced skin inflammation in controlled conditions. This is relevant for anyone using castor oil on irritated, reactive, or inflamed skin, including the delicate skin around the eyes and brows.

3. Antimicrobial properties

Castor oil has demonstrated antimicrobial activity against several strains of bacteria and fungi in laboratory studies. For skin use, this may contribute to its traditional reputation for supporting clear, calm skin when used consistently. For lash and brow use, it may help maintain a healthy follicle environment.

Castor oil for lashes and brows

The use of castor oil on eyelashes and eyebrows is one of its most widely discussed applications — and one of the most frequently asked about by customers considering the Selfwise Organic Castor Oil Face Moisturizer.

The honest answer is that the direct clinical evidence for castor oil growing lashes or brows is limited. There are no large randomised controlled trials specifically measuring lash length or brow density following castor oil application. What is documented is that ricinoleic acid can condition and nourish hair follicles, reduce protein loss from hair strands, and improve the overall appearance of thickness and health in existing hair.

For lashes and brows specifically, consistent application of castor oil may help reduce breakage, improve the appearance of thickness in existing hairs, and keep the follicle environment healthy. Many users report visible improvement in lash and brow fullness within 4 to 8 weeks of nightly application — though individual results vary depending on baseline hair density and consistency of use.

Best for lashes and brows: apply a small amount to clean lashes or brow hairs with a clean mascara wand or cotton swab each night before sleep. Remove in the morning as part of your regular cleanse.

Castor oil for the face and skin

On the face, castor oil functions primarily as a deeply nourishing moisturiser. Its thick consistency means a very small amount goes a long way — this is not an oil you apply in the same quantities as a serum or lightweight facial oil. A single drop warmed between fingertips and pressed gently into skin provides full coverage for most areas.

Castor oil is well suited to dry, dehydrated, and sensitive skin types. Its low comedogenic rating (1 out of 5) means it is unlikely to clog pores for most people — but those with very oily or acne-prone skin should patch test before applying to the full face, as individual responses vary.

The Selfwise Organic Castor Oil Face Moisturizer blends organic castor oil with seven complementary botanicals — jojoba, rosehip, grapeseed, squalane, palmarosa, bergamot, and vitamin E — for a more complete daily facial oil that balances the thickness of castor oil with lighter, faster-absorbing ingredients.

Castor oil for hair

In hair care, castor oil is most commonly used as a scalp treatment and hair mask ingredient. Applied to the scalp, it can help soothe dryness, reduce flaking, and support a healthy follicle environment. Applied through the lengths of the hair, it conditions, adds shine, and helps reduce breakage and split ends.

Because of its viscosity, pure castor oil can be difficult to apply evenly and hard to rinse from hair when used alone. Blending it with lighter oils — as in the Selfwise Rosemary & Multi-Oil Hair Growth Oil — makes it easier to work with while preserving its nourishing properties.

Who is castor oil best for?

✓ Best for: Dry, sensitive, or mature skin — sparse or brittle lashes and brows — coarse, dry, or damaged hair — people wanting a clean, multi-use botanical oil with minimal ingredients

✗ Not for: Very oily or acne-prone skin without patch testing first — anyone with a known sensitivity to Ricinus communis — use around the eyes requires care to avoid direct eye contact

How to use castor oil

Face moisturiser: Apply 1–2 drops to clean, slightly damp skin. Warm between palms and press into the skin rather than rubbing. Can be used morning or evening, or both. A little goes a long way — start small.

Lashes and brows: Using a clean mascara wand or cotton swab, apply a small amount to lash line and brow hairs before sleep. Remove gently in the morning. Use nightly for 4 to 8 weeks to assess results.

Scalp and hair: Apply to the scalp in sections, massage gently, and leave for at least 30 minutes before washing — or leave overnight for a deeper treatment. Can also be applied through dry or damp hair lengths as a conditioning treatment.

Lips and cuticles: Apply a small amount directly. Its thick consistency makes it ideal for very dry areas.

Common questions about castor oil

Is organic cold-pressed castor oil better?

Yes, for topical use. Cold-pressed, organic castor oil retains more of its natural fatty acids, antioxidants, and beneficial compounds compared to refined or hexane-extracted versions. The Selfwise formula uses organic castor oil specifically for this reason.

Can I use castor oil every day?

Yes. Castor oil is suitable for daily use on skin, lashes, brows, and hair. It is gentle enough for sensitive skin and does not cause sensitisation with regular use for most people.

How long does it take to see results?

For skin moisturisation, results are immediate — skin feels softer and more hydrated from first use. For lash and brow fullness, allow 4 to 8 weeks of consistent nightly use. For hair health, improvements in manageability and shine are typically noticeable within 2 to 4 weeks.

Is castor oil safe to use around the eyes?

Yes, when applied carefully. Castor oil is used as an ingredient in many eye drops and ophthalmic preparations due to its safety profile. Apply to the lash line and brow — not directly into the eye. If direct eye contact occurs, rinse with clean water.

Will castor oil clog my pores?

Castor oil has a comedogenic rating of 1 out of 5, which means it is considered low-risk for pore-clogging. Most skin types tolerate it well. Those with very oily or acne-prone skin should patch test on a small area first before applying to the full face.

Can I use castor oil during pregnancy?

Topical use of castor oil on skin, lashes, brows, and hair is generally considered safe during pregnancy. Oral consumption of castor oil is not recommended during pregnancy and is a separate, unrelated use case. As always, consult your healthcare provider if you have specific concerns.

What's the difference between castor oil and Jamaican black castor oil?

Jamaican black castor oil is made by roasting castor beans before pressing, which gives it a darker colour and a stronger, smoky scent. The roasting process may increase ash content, which some believe adds additional cleansing properties for the scalp. Regular cold-pressed castor oil is lighter in colour and scent and is better suited for facial and lash use. Both are derived from Ricinus communis and have similar fatty acid profiles.

Selfwise products with castor oil

Organic Castor Oil Face Moisturizer — organic castor oil blended with jojoba, rosehip, grapeseed, squalane, palmarosa, bergamot, and vitamin E. Designed for face, lashes, brows, lips, and cuticles. Available in 1oz, 2oz, and 4oz.
Rosemary & Multi-Oil Hair Growth Oil — features castor oil alongside rosemary, coconut, argan, jojoba, grapeseed, sweet almond, avocado, vitamin E, lavender, and peppermint. Designed for scalp and hair treatment.