Jojoba oil an updated review on chemistry, pharmaceutical use and toxicity

Background

Jojoba oil is pressed from the seeds of Simmondsia chinensis, a desert shrub native to the Sonoran regions of North America and now cultivated commercially in countries such as Egypt, Chile and Argentina. Unlike most plant oils, which are made up mainly of triglycerides, jojoba oil is almost 98% wax esters - long-chain fatty acids joined to long-chain fatty alcohols - alongside smaller amounts of sterols, free fatty acids and vitamins. This unusual wax-ester structure gives it different stability, texture and skin-penetration properties compared with conventional plant oils, which the authors say has driven centuries of traditional use and a growing body of modern pharmaceutical and cosmetic research.

Study design

This is a narrative literature review rather than a clinical trial or laboratory study. The authors searched the Scifinder, PubMed and Web of Science databases from 1990 to 2021 using combinations of keywords such as "jojoba", "Simmondsia", "chemistry", "pharmaceutical preparations", "toxicity" and "biological activity", restricted to English-language publications. They then synthesised the identified literature covering jojoba oil's chemical composition, its use in topical and pharmaceutical formulations, its industrial applications, and the available toxicity and safety data.

Findings

Across the studies reviewed, jojoba oil and jojoba-based formulations were repeatedly linked to beneficial topical effects. Microemulsions and emulgels containing jojoba oil improved the anti-inflammatory action of drugs such as diclofenac compared with a standard marketed gel, and reduced skin irritation and dryness when combined with benzoyl peroxide for acne. Formulations for psoriasis (using methotrexate or tazarotene) showed better skin penetration and comparable or improved clinical effect with less irritation than standard marketed products. Jojoba-based emulgels containing clotrimazole showed stronger antifungal activity against Candida albicans than two commercial antifungal products, and jojoba oil itself showed inhibitory activity against several bacteria in older studies. In animal work, jojoba oil reduced inflammation and prostaglandin E2 levels, apparently by blocking the cyclooxygenase and lipoxygenase enzyme pathways, and a small controlled trial found jojoba liquid wax as effective as a steroid-antibiotic combination for treating nappy rash, without the same systemic side-effect risk.

On toxicity, the review reports that crude jojoba oil showed no acute toxicity when fed to mice, with a lethal dose above 160 grams per kilogram of body weight. Ocular application in rabbits caused only mild, reversible irritation that cleared within 24 hours, and repeated skin-patch testing in guinea pigs produced only mild, reversible swelling. Human patch and prick testing found no allergic reactions except in people who were already highly allergy-prone, and a mixture of jojoba oil and hydrogenated jojoba wax was not mutagenic in standard bacterial (Ames) testing.

What the authors concluded

The authors concluded that jojoba oil's distinctive wax-ester chemistry underpins a genuinely versatile ingredient, with well-supported topical benefits (anti-inflammatory, antimicrobial, antifungal and skin-penetration-enhancing effects) and a favourable safety profile in the animal and human data available. They describe jojoba as one of the "top-ranked" natural oils and argue it deserves continued research and development as both a pharmaceutical excipient and an industrial raw material, including in polymer and biodiesel production.

Limitations of this study

As a narrative rather than systematic review, the authors did not apply formal quality-scoring or risk-of-bias criteria to the studies they included, so the strength of evidence behind individual claims varies considerably, from well-controlled animal experiments to smaller or older human studies. Much of the pharmaceutical efficacy evidence comes from laboratory and animal models rather than large human clinical trials, and the toxicity data summarised are largely older studies focused on topical and acute oral exposure, with limited discussion of long-term or chronic safety. The review also does not address batch-to-batch variability in jojoba oil composition arising from different growing regions or processing methods, which could affect how consistently these findings translate to any single commercial product.