When it comes to using ingredients and chemicals on the eyes, it is crucial to consider formulation. This is especially important because many chemicals share names but come from different sources. This can be said about castor oil.

Origins
Castor oil is rich in ricinoleic acid and has been used historically for constipation, muscle aches, and insomnia.¹ Ricinoleic acid makes up 87% to 90% of castor oil, and is an unsaturated fatty acid that has surfactant, skin conditioning, and emulsion-stabilizing properties.² Castor oil’s molecule has both hydrophilic and hydrophobic parts, making it a great moisturizer.²

Established uses
Industrial grade castor oil is used for topical skin conditioning, as an emulsion stabilizer, and as a surfactant found in creams, cosmetics, hair-growth products, and in eye makeup removers. Castor oil is also already in use, in lower concentration, in some OTC artificial tears that are emulsions and prescription drops containing cyclosporine. This synthetic mimics our complex natural lipids, but is just that: synthetic. It has been postulated that it may be more beneficial to utilize a non-polar lipid, such as cholesterol and wax esters found at a higher concentration in our natural tears.³

Recent claims
TikTok trends and the like have touted benefits of castor oil, ranging from decreasing the need for glasses, to even curing eye infections, glaucoma, and cataracts. No data backs up these claims. That said, there is some merit in castor oil as a treatment for blepharitis, meibomian gland dysfunction (MGD), and dry eye.¹ In respect to dry eye, it is believed improvement is achieved by increasing the thickness and composition of the lipid layer in the tear film.² While exact mechanism of action and true level of improvement with blepharitis and MGD is unknown, it is believed to be related to anti-inflammatory and anti-microbial properties of ricinoleic acid and R. communis, respectively.² Regardless the intended ocular use, a big concern is that patients are turning to social media for “medical care” instead of a licensed doctor.

The challenge
Many patients seeking castor oil for ocular use aren’t going for eye-friendly formulations. Castor oil found on store shelves or through online sources are not meant to be used on the eyes and may, in fact, contain dyes, preservatives, fragrances or other ingredients that could cause irritation. Also, because these formulations may not be sterilized, their use could lead to infection.⁴

Patient education
Let’s educate our patients that while castor oil has been heralded for various health and cosmetic benefits, its application in ocular health demands careful consideration: “Though some studies suggest that castor oil can help with conditions like blepharitis and dry eye, it is critical to use formulations designed for ocular use. Products not intended for the eyes may contain harmful additives or lack proper sterilization, posing serious risks. Thus, it’s essential you consult with me and your other health care providers before use.” OM

References:

1. Sandford EC, Muntz A, Craig JP. Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye. Clin Exp Optom. 2021;104(3):315-322. doi: 10.1111/cxo.13148.
2. Marwat SK, Rehman F, Khan EA et al. Ricinus cmmu-nis: Ethnomedicinal uses and pharmacological activities. Pak J Pharm Sci. 2017; 30(5): 1815–1827.            
3. Maulvi FA, Desai DT, Kalaiselvan P, Dumpati S, Kuppusamy R, Masoudi S, Shah DO, Willcox MDP. Lipid-based eye drop formulations for the management of evaporative dry eyes. Cont Lens Anterior Eye. 2024 Jun;47(3):102154.
4. Al Hassan S, Bou Ghannam A, S Saade J. An Emerging Ophthalmology Challenge: A Narrative Review of TikTok Trends Impacting Eye Health Among Children and Adolescents. Ophthalmol Ther. 2024 Apr;13(4):895-902.

Cecelia Koetting, OD, FAAO is a clinical instructor at the University of Colorado School of Medicine. She is a fellow of the American Academy of Optometry, diplomate of the American Board of Optometry, an active American Optometric Association member, and she consults for multiple companies. Email her at Dr.CeceliaKoetting@gmail.com.