Castor oil is a thick, pale vegetable oil with a surprisingly wide range of uses, from relieving constipation to moisturizing skin and hair. About 87% to 90% of the oil is made up of a single fatty acid called ricinoleic acid, which gives castor oil its distinctive properties: anti-inflammatory, antimicrobial, and deeply moisturizing. That unusual concentration of one active compound is why castor oil shows up in medicine cabinets, skincare routines, and even prescription wound-care products.
Constipation Relief
The most well-established use for castor oil is as a laxative. It holds FDA approval as an over-the-counter drug for occasional constipation. When you swallow it, enzymes in your small intestine break it down into ricinoleic acid, which stimulates the intestinal walls to contract and push stool through. The effect is fast. Most people experience a bowel movement within two to six hours.
The standard adult dose is 1 to 4 tablespoons (15 to 60 mL) taken once. For children ages 2 to 12, the dose drops to 1 to 3 teaspoons (5 to 15 mL). It tastes unpleasant on its own, so mixing it into juice or chilling it first helps. This is a short-term remedy, not something to use regularly. Repeated use can lead to dependence, where your bowels stop moving normally without it.
Skin Moisturizer and Barrier Protection
Castor oil works as an occlusive moisturizer, meaning it sits on top of the skin and physically blocks water from evaporating. That thick, almost sticky texture is the feature, not a flaw. The ricinoleic acid strengthens the skin barrier and helps skin retain moisture longer than thinner oils like coconut or jojoba.
It also has antimicrobial and anti-inflammatory properties. Bacteria on the face can clog pores and trigger breakouts, so an oil that fights bacteria while moisturizing can work well for certain skin types. That said, castor oil is heavy. If your skin is already oily or acne-prone, applying it undiluted to your entire face may clog pores rather than clear them. Many people dilute it with a lighter carrier oil or use it only on dry patches, lips, or cuticles.
For dry or cracked skin on the hands, feet, or elbows, castor oil performs well as an overnight treatment. Apply a thin layer, cover with socks or gloves, and let it absorb while you sleep. The occlusive film traps moisture against the skin all night.
Wound Healing
Castor oil appears in at least one prescription wound-care product, an ointment combining balsam peru and castor oil that’s used on pressure ulcers and chronic wounds. The ointment creates a moist wound environment that supports healing, prevents cracking around wound edges, and helps reduce pain. This isn’t something you’d buy off the shelf for a paper cut, but it shows that the moisturizing and protective qualities of castor oil have genuine clinical applications beyond cosmetics.
Hair and Scalp Health
Castor oil is one of the most popular natural hair treatments, and there’s a biological reason it may actually help. Ricinoleic acid appears to increase levels of prostaglandin E2, a lipid compound that plays a role in hair growth. This is the same pathway that minoxidil, the active ingredient in Rogaine, targets. No large clinical trials have confirmed that castor oil regrows hair on its own, but the shared mechanism is plausible enough to explain why so many people report thicker-looking hair after consistent use.
Where castor oil clearly delivers is scalp health. Its antimicrobial properties can help keep the scalp clean, while its thick consistency coats and protects individual hair strands from breakage. Hair that breaks less looks fuller over time, even without new growth. For a scalp treatment, massage a small amount into the roots, leave it on for 30 minutes to overnight, then shampoo it out. Because the oil is so thick, you may need to shampoo twice.
People also apply it to eyebrows and eyelashes for the same reasons. A tiny amount on a clean mascara wand, applied nightly, is a common approach. Results, if any, take weeks to become noticeable.
Labor Induction: What the Evidence Says
Castor oil has been used for decades as a folk remedy to induce labor in overdue pregnancies. The idea is that the same intestinal contractions that relieve constipation might also stimulate uterine contractions. A Cochrane systematic review looked at the available clinical trials, which included only 233 women across three studies, and found insufficient evidence to draw any conclusions about whether castor oil actually works for this purpose. There was no clear difference in cesarean section rates, instrumental deliveries, or newborn health outcomes between castor oil and placebo groups. The sample sizes were simply too small to detect anything beyond large effects. Given the lack of solid evidence and the guaranteed side effect of diarrhea and cramping, this is a use best discussed with a midwife or doctor rather than attempted independently.
Safety and the Ricin Question
Castor oil comes from the seeds of the castor plant, the same plant that produces ricin, one of the most toxic natural substances known. This understandably makes people uneasy. The key distinction is in the processing. Ricin is a protein, and proteins break down (denature) at relatively low temperatures. Hot-pressing castor seeds during oil extraction destroys the ricin completely. Research confirms that the ricin protein irreversibly unfolds at temperatures as low as 70°C (158°F), and hot-pressed castor meal shows no detectable ricin at all. Commercial castor oil sold for consumer use contains no ricin and is safe to ingest at recommended doses or apply to the skin.
The most common side effects of oral use are nausea, cramping, and diarrhea, which are really just extensions of the laxative effect. For topical use, allergic reactions are possible but uncommon. If you’ve never used castor oil on your skin before, test a small patch on the inside of your forearm and wait 24 hours before applying it more broadly.
Choosing and Storing Castor Oil
Cold-pressed, hexane-free castor oil retains the most ricinoleic acid and is the best choice for both skin and internal use. Jamaican black castor oil, which is roasted before pressing, has a darker color and slightly different scent but works similarly. For topical use, either type is fine. For oral use as a laxative, look for a product specifically labeled for internal use or sold as a dietary supplement or drug.
Unopened castor oil lasts one to two years when stored properly. Once opened, aim to use it within six to twelve months. Keep it in a cool, dark place between 50 and 70°F, ideally in a dark glass bottle with a tight seal. Plastic containers can react with the oil over time, and heat and light accelerate oxidation, which makes the oil go rancid. If it smells sour or off, discard it.