New Zealand's native manuka and kanuka plants are famous for honey — but their oils also have a growing reputation in skin and eye care. A 2025 University of Auckland study put a castor oil blend containing manuka and kanuka oils to the test against Demodex mites. Here's what the research actually showed.
Why manuka and kanuka?
Both are botanical oils from New Zealand's Leptospermum and Kunzea plants, traditionally valued for antimicrobial and soothing properties. The idea behind combining them with castor oil is to pair castor oil's gentle, conditioning base with additional botanical activity — potentially boosting the effect against mites while keeping the preparation tolerable for the eye area.
What the study found
Researchers exposed live Demodex mites (collected from eyelashes with cylindrical dandruff) to different oils and tracked how long they survived. Results for the castor-based preparations:
Preparation
Median mite survival
100% cold-pressed castor oil
~235 minutes (~4 hours)
Castor oil + manuka & kanuka oils
~325 minutes (~5.4 hours)
Both preparations clearly shortened mite survival compared with unexposed mites — confirming anti-Demodex activity. Interestingly, there was no statistically significant difference between plain castor oil and the manuka/kanuka blend in this test. In other words, the botanical additions didn't dramatically outperform pure castor oil against the mites in this particular ex vivo setup.
What that means in practice
The takeaway isn't that manuka and kanuka are pointless — they may contribute soothing or antimicrobial benefits to the lid margin beyond raw mite survival time, which this study wasn't designed to capture. But it does mean that pure 100% cold-pressed castor oil already carries the core anti-Demodex effect, so you don't need an exotic blend to get the main benefit. Both landed comfortably within the overnight (under-eight-hour) window the researchers highlighted.
An honest note on evidence
This was a laboratory (ex vivo) study on mites removed from lashes, not a clinical trial — so it shows biological activity and rationale, not proven patient outcomes. The authors called for further clinical testing. As always, choose eye-safe, properly formulated products and avoid applying undiluted essential oils near the eyes.
The proven core, kept simple: Meibocare LidBoost+ delivers 100% cold-pressed castor oil — the preparation that carried the anti-Demodex effect in this research — in an easy roller-ball for the lash line.
Frequently asked questions
Is manuka and kanuka oil better than castor oil for Demodex?
In the 2025 ex vivo study, a castor oil blend with manuka and kanuka shortened mite survival, but not significantly more than pure castor oil. The core anti-Demodex effect came from the castor oil itself.
Can I put manuka oil directly on my eyelids?
Only use products specifically formulated and diluted for the eye area. Undiluted essential oils, including manuka, can irritate the eyes — a gentle castor oil base is safer for daily use.
Educational information only, not medical advice. Reference: Jennings CJ, et al. Anti-Demodex activity of castor oil confirmed in an ex vivo study. Contact Lens and Anterior Eye. 2025.doi:10.1016/j.clae.2025.102471 (PubMed)
