Oils (coconut, argan, olive, mineral)
Pre-wash treatments, shine and softness — and descaling in some medicines Also on labels as: Cocos nucifera oil, Argania spinosa kernel oil, Olea europaea oil, paraffinum liquidum
Reviewed on
What it does
Oils are among the oldest hair treatments, but a hair-science review notes there are "few articles" on their effects. What the research says:
- Coconut oil — in a laboratory study (funded by a coconut hair oil maker), it was the only one of three oils tested that reduced protein loss from hair when used before and after washing; it can penetrate the hair shaft, unlike mineral oil. A 2022 systematic review found clinical evidence for coconut oil in brittle hair (and head lice), with little evidence for hair growth.
- Argan oil — the same systematic review found no significant evidence that argan oil improves hair growth or quality. A lab study suggested it may protect hair from oxidative damage.
- Olive oil — lab work suggests it is partly absorbed into hair; we found no clinical studies.
- Mineral oil — doesn't penetrate hair but coats the surface, which can add shine and reduce friction.
Oils that get into the hair may reduce how much it swells with water, which researchers think may reduce damage from repeated wetting and drying. Many dermatologists are relaxed about hair oils because they're unlikely to cause harm, rather than because they're proven to help.
On the scalp, oils have a medical use: coconut oil is used with salicylic acid in descaling products for seborrhoeic dermatitis and scalp psoriasis.
Cautions
- Heavy oils on the scalp can add to greasiness and build-up.
- Babies: for cradle cap the NHS suggests coconut oil or an emollient, but says not to use olive oil (may not be suitable for skin) or peanut oil (allergy risk).
- Allergic reactions to plant oils (including argan) are possible — patch-test if you have sensitive skin.
How strong is the evidence?
Evidence: Cosmetic
Changes how hair looks or feels; not a treatment for any condition.
Mostly laboratory studies on hair fibres, plus a systematic review that found limited clinical evidence. Rated cosmetic.
Products on this site that list it
- Bouclème Curl Cleanser
- Philip Kingsley Elasticizer Pre-Shampoo Treatment
- Remington Shine Therapy Straightener S8500
Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.
Sources
- Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology 2015 pmc.ncbi.nlm.nih.gov
- Rele AS, Mohile RB. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. J Cosmet Sci 2003 pubmed.ncbi.nlm.nih.gov
- Keis K et al. Investigation of penetration abilities of various oils into human hair fibers. J Cosmet Sci 2005 pubmed.ncbi.nlm.nih.gov
- Phong C et al. Coconut, castor, and argan oil for hair in skin of color patients: a systematic review. J Drugs Dermatol 2022 pubmed.ncbi.nlm.nih.gov
- Sharifi N et al. J Cosmet Dermatol 2022 (argan oil and oxidative hair damage) pubmed.ncbi.nlm.nih.gov
- Foti C et al. Allergic contact dermatitis caused by argan oil. Contact Dermatitis 2014 pubmed.ncbi.nlm.nih.gov
- NHS – Cradle cap nhs.uk
- British Association of Dermatologists – Seborrhoeic dermatitis bad.org.uk