Castor Oil: All-Purpose Life-Changer, Or Snake Oil?

As “trending” health products go, castor oil is enjoying a lot of popularity presently, lauded as a life-changing miracle-worker, and social media is abuzz with advice to put it everywhere from your eyes to your vagina.

But:

• what things does science actually say it’s good for,
• what things lack evidence, and
• what things go into the category of “wow definitely do not do that”?

We don’t have the space to go into all of its proposed uses (there are simply far too many), but we’ll examine some common ones:

To heal/improve the skin barrier

Like most oils, it’s functional as a moisturizer. In particular, its high (90%!) ricinoleic fatty acid content does indeed make it good at that, and furthermore, has properties that can help reduce skin inflammation and promote wound healing:

Bioactive polymeric formulations for wound healing ← there isn’t a conveniently quotable summary we can just grab here, but you can see the data and results, from which we can conclude:

• formulations with ricinoleic acid (such as with castor oil) performed very well for topical anti-inflammatory purposes
• they avoided the unwanted side effects associated with some other contenders
• they consistently beat other preparations in the category of wound-healing

To support hair growth and scalp health

There is no evidence that it helps. We’d love to provide a citation for this, but it’s simply not there. There’s also no evidence that it doesn’t help. For whatever reason, despite its popularity, peer-reviewed science has simply not been done for this, or if it has, it wasn’t anywhere publicly accessible.

It’s possible that if a person is suffering hair loss specifically as a result of prostaglandin D2 levels, that ricinoleic acid will inhibit the PGD2, reversing the hair loss, but even this is hypothetical so far, as the science is currently only at the step before that:

In silico prediction of prostaglandin D2 synthase inhibitors from herbal constituents for the treatment of hair loss

However, due to some interesting chemistry, the combination of castor oil and warm water can result in acute (and irreversible) hair felting, in other words, the strands of hair suddenly glue together to become one mass which then has to be cut off:

“Castor Oil” – The Culprit of Acute Hair Felting

👆 this is a case study, which is generally considered a low standard of evidence (compared to high-quality Randomized Controlled Trials as the highest standard of evidence), but let’s just say, this writer (hi, it’s me) isn’t risking her butt-length hair on the off-chance, and doesn’t advise you to, either. There are other hair-oils out there; argan oil is great, coconut oil is totally fine too.

As a laxative

This time, there’s a lot of evidence, and it’s even approved for this purpose by the FDA, but it can be a bit too good, insofar as taking too much can result in diarrhea and uncomfortable cramping (the cramps are a feature not a bug; the mechanism of action is stimulatory, i.e. it gets the intestines squeezing, but again, it can result in doing that too much for comfort):

Castor Oil: FDA-Approved Indications

To soothe dry eyes

While putting oil in your eyes may seem dubious, this is another one where it actually works:

❝Castor oil is deemed safe and tolerable, with strong anti-microbial, anti-inflammatory, anti-nociceptive, analgesic, antioxidant, wound healing and vasoconstrictive properties.

These can supplement deficient physiological tear film lipids, enabling enhanced lipid spreading characteristics and reducing aqueous tear evaporation.

Studies reveal that castor oil applied topically to the ocular surface has a prolonged residence time, facilitating increased tear film lipid layer thickness, stability, improved ocular surface staining and symptoms.❞

Source: Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye

Against candidiasis (thrush)

We couldn’t find science for (or against) castor oil’s use against vaginal candidiasis, but here’s a study that investigated its use against oral candidiasis:

Rosemary, Castor Oils, and Propolis Extract: Activity Against Candida Albicans and Alterations on Properties of Dental Acrylic Resins

…in which castor oil was the only preparation that didn’t work against the yeast.

Summary

We left a lot unsaid today (so many proposed uses, it feels like a shame to skip them), but in few words: it’s good for skin (including wound healing) and eyes; but we’d give it a miss for hair, candidiasis, and digestive disorders.

Want to try some?

We don’t sell it, but here for your convenience is an example product on Amazon 😎

Take care!