Castor oil after a hair transplant: evidence, timing and risks

Where does castor oil’s reputation for hair come from?

This vegetable oil is pressed from the seeds of Ricinus communis. About 90% of its fatty acids are ricinoleic acid, a monounsaturated omega-9 fatty acid responsible for most of its chemical profile (Girdler et al., 2026). It is very viscous and has long been used in a wide range of cosmetics.

Its use on hair is first and foremost cultural. In African, Caribbean, Indian and Indigenous American traditions, it has been used for generations to care for hair and scalp, particularly textured hair. People expect it to add shine, make hair easier to style, keep the lengths moisturised and soothe a dry or itchy scalp, although most of these uses have never been studied for clinical efficacy (Girdler et al., 2026).

Around hair transplants, many websites credit it with three further effects: stimulating graft growth, reducing inflammation and strengthening the new hairs. These claims often point back to a single 2015 paper on prostaglandin D2, whose method has to be understood to judge what it establishes.

Does castor oil help transplanted hair grow?

A hypothesis calculated by computer

Prostaglandin D2 (PGD2) is a molecule that research links to androgenetic alopecia, the common pattern hair loss, and blocking its production was a recent treatment idea in 2015. That year, a team in Macao screened 389 compounds from twelve plants used in traditional Chinese medicine to find those that might block the enzyme producing PGD2. The work relied on molecular docking, a simulation that calculates how strongly a molecule should bind to an enzyme, combined with predictions of skin penetration and tolerance (Fong et al., 2015).

Ricinoleic acid was one of the five compounds identified as likely inhibitors with a profile suited to application on skin. The authors presented them as candidates for future laboratory and in vivo studies, since their study involved no follicles, no animals and no patients. A website claiming that castor oil “blocks PGD2” and “restarts growth” is therefore presenting a prediction as a result. A 2026 review describes the clinical value of acting on this pathway in androgenetic alopecia as uncertain, and notes that a placebo-controlled trial of setipiprant, a drug that blocks the PGD2 receptor, showed no efficacy in men with this condition (Girdler et al., 2026).

What a systematic review concluded

In 2022, a systematic review brought together 22 publications on three widely used oils, coconut, castor and argan, to check their effects on hair growth, hair quality and scalp infestations. For castor oil, the available data offer weak support for improved shine of the hair shaft, and no strong evidence supports its use to grow hair (Phong et al., 2022).

The reviewers point out that these oils belong to long-standing cultural practices, and that many dermatologists advise continuing them because no side effects are foreseeable, without relying on proven clinical efficacy. None of these data concern an operated scalp: neither graft survival nor the tolerance of the oil on micro-incisions has been the subject of a published study.

Claimed effect	What studies show
Stimulates growth	Hypothesis from a simulation
Soothes inflammation	Not tested on an operated scalp
Improves graft survival	No published study
Makes hair shiny	Limited, favourable data

Why a transplant changes things in the first weeks

An FUE or DHI transplant leaves hundreds, often thousands, of micro-incisions on the scalp: in the donor area, where the follicular units were harvested, and in the recipient area, where each one was implanted. Both stages are described in our complete guide to hair transplantation. Until these openings close, any product applied touches broken skin, and each graft can still move within its site.

Bernstein and Rassman (2006) tested how firmly grafts held in 42 patients as the days went by. A tug on the implanted hair was enough to pull out the graft during the first two days and no longer did so by day six; pulling off a stuck scab still removed it up to day five, and only on day nine did every graft hold. The authors concluded that scabs lengthen the period at risk and that limiting their formation would shorten it, which is the purpose of the gentle washing explained in our page on the scabs that form after a transplant.

A thick oil alters these conditions in two ways. It does not rinse out well with plain water, so removing it calls for firmer shampooing and therefore more handling of an area where every rub counts. It is also spread on skin whose protective outer layer is broken, while contact dermatitis arises either when an irritant damages that layer or when an allergen triggers an immune response in the skin (NHS, 2023).

During this period, it is often itching that prompts people to look for something to apply. It usually starts within the first week and fades over a few days or weeks; Romera de Blas and colleagues (2026) link it to forming scabs, drying skin and an epidermis that is still rebuilding itself. Each of these causes has its own remedies, covered further down, none of which requires an oil.

When can castor oil be considered?

No study sets a date, and the timings found online range from two weeks to three months. The most reliable guide is the state of your skin. Three signs should all be present before you raise the subject with the team: every scab has fallen off by itself and the skin has closed without oozing, any redness has gone or is clearly fading, and no spots or persistent itching suggest folliculitis or irritation.

Scabs usually come away within about ten days, but folliculitis can still appear up to the fourth week, and redness around the grafts sometimes lasts longer (Romera de Blas et al., 2026). A delay of about a month covers this period; treat it as a guide to confirm with the team, who can judge your healing from photos or at a check-up.

Stage	What applies
Days 1 to 9	Prescribed aftercare only
Scabs still present	Prescribed aftercare only
Spots or marked redness	Ask the team first
Skin closed and settled	Oil possible, if approved

With Body Expert, your scalp is washed for the first time at the clinic the day after surgery, and you leave with the washing products to use from then on. This care fits into the wider recovery timeline, from rest in the first days to returning to your usual activities, which we set out in our guide to hair transplant aftercare.

What are the risks of castor oil on a transplanted scalp?

Contact allergy and irritation

Castor oil is generally well tolerated, but it can cause contact dermatitis. The review by Girdler et al. (2026) names this as its most frequent side effect, described mainly with make-up, shampoos and deodorants containing it, and regards the ricinoleic acid in non-hydrogenated oil as the most likely sensitising agent. The authors also cite the case of a man who developed dermatitis from a dressing containing castor oil, a setting close to that of a healing wound.

An allergen acts through the immune system, which first has to become sensitised, so a first application that goes smoothly does not rule out a reaction later. Contact dermatitis makes the skin itchy, dry, cracked and sometimes blistered, and the reaction usually appears within a few hours or days of exposure; on lighter skin it looks red, while on darker skin it can appear dark brown, purple or grey (NHS, 2023). A pharmacist can advise on a troublesome reaction, and a GP should see one that persists, recurs or is severe (NHS, 2023); according to Girdler et al. (2026), most are mild and can be treated quickly.

Signs that are easy to confuse

Lasting redness, intense itching or small spots around the grafts can point to folliculitis, infection or a reaction to a product. Romera de Blas et al. (2026) advise looking for contact dermatitis or a reaction to a hair care product when itching persists. Adding an oil during this period complicates that sorting, because it becomes harder for the team to tell the course of healing apart from the effect of the product.

Felting of long hair

A rare mishap affects hair long enough to tangle: acute hair felting, in which the hair suddenly turns into a compact mass that cannot be combed out. One case was described immediately after a very first application of castor oil, and the only solution was to cut off the affected hair (Girdler et al., 2026). The risk mainly concerns people who keep longer hair around the grafted area, for example after a female hair transplant.

Sign	What to do
Stinging soon after applying	Rinse, stop the product
Itchy, inflamed patches	Stop, send a photo
Pus or worsening pain	Seek medical advice promptly
Hair matted into a mass	Do not pull, ask for advice

How to use it if the team gives the go-ahead

Once healing is complete and you have the team’s agreement, castor oil can be used as a cosmetic, with a few precautions. Choose a pure oil without added fragrance or essential oils, to limit the number of ingredients that could sensitise you. Start with a test: apply a drop to a small patch of healthy skin away from the grafted area and watch it for at least 48 hours, since an allergic reaction can take hours or days to appear.

If your skin does not react, a small amount is enough. Apply it with your fingertips, without vigorously massaging the grafted area, leave it on briefly, then wash it out with the gentle shampoo recommended by the clinic. Avoid starting any other new product at the same time, so that any reaction can be traced back to the oil, and stop at the first sign of a spot, redness or new itching.

On the lengths, once the transplanted hair has grown, castor oil behaves like other cosmetic oils. Its best-documented effect concerns the shine of the hair shaft (Phong et al., 2022). On long hair, detangle it before applying the oil and rinse without rubbing the hair together in a mass.

What to use instead to moisturise the scalp and support regrowth?

During healing, useful care targets the causes of dryness and itching directly. Romera de Blas et al. (2026) list regular saline sprays and gentle cleansing to remove scabs and keep the skin hydrated, along with emollient lotions or moisturisers designed for use after a transplant, to ease dryness. How often to spray, and for how long, is explained in our article on saline spray after a hair transplant.

Intense or lasting itching calls for medical advice: the same review then mentions oral antihistamines or low-potency topical corticosteroids, prescribed case by case. It is also the moment to check that no added product is keeping the problem going.

For regrowth, the question of treatment arises mainly for the native hairs around the grafted area. Their temporary loss, known as shock loss, affects some patients between the second and eighth week, and the review by Romera de Blas lists minoxidil, as a lotion or by mouth, among the treatments that may speed up regrowth. Its use after surgery, like that of finasteride, is a decision to make with a doctor; both medicines are covered in a separate piece on minoxidil and finasteride after a hair transplant.

The other oils suggested after a transplant, such as coconut oil, argan oil or rosemary essential oil, raise the same questions of timing and tolerance on a healing scalp. What the studies say about each one is set out in our selection of the best oils for hair growth.

Frequently asked questions about castor oil and hair transplants

Is castor oil toxic, given that it comes from the castor plant?

Ricin, the plant’s toxin, is found in its seeds, and the purified oil sold for cosmetic use does not contain it (Girdler et al., 2026). The danger lies with the seeds themselves, which should never be crushed to make a home remedy.

Can castor oil be mixed with a minoxidil solution?

It is best not to do so without medical advice. Dermatology uses castor oil to increase the skin penetration of certain active ingredients (Girdler et al., 2026): mixed with a medicine, it can change how much of it passes through the skin, and therefore how well it is tolerated. If both products are allowed, ask the team how to space out their applications.

Can castor oil be left on overnight?

Nothing suggests that a longer contact time brings any benefit. A whole night does, however, prolong contact with the skin, and with it exposure to a possible allergen, and the oil rubs off onto the pillow. In the first months after the transplant, a short application followed by a gentle shampoo remains the safer option.

How long does castor oil take to make transplanted hair grow?

No timescale can be given, since an effect on growth has not been demonstrated. Transplanted hair follows its own timetable: the implanted shafts may shed in the first weeks, new hairs usually become visible from the third or fourth month, and the result is judged between twelve and eighteen months, as described in our hair transplant timeline.

Your hair care after surgery with Body Expert

Before you fly home, the team at our partner clinic in Istanbul explains the aftercare to continue at home. If you later consider castor oil, or any other oil, photograph the label and send it to your English-speaking patient coordinator, together with a photo of your scalp taken in daylight, so that the medical team can reply according to how your skin is healing.

Your package includes a 12-month post-operative follow-up, which also covers the first months of regrowth, so you can go over with the team the hair care you would like to resume as the new hairs appear and lengthen.

If you are planning your stay, our overview of hair transplant in Istanbul explains how it is organised, from airport pick-up to your transfer back to the airport. Once your photos are with us, a free, no-obligation quote reaches you within 24 hours.

Sources

Bernstein, R. M., & Rassman, W. R. (2006). Graft anchoring in hair transplantation. Dermatologic Surgery, 32(2), 198-204. https://doi.org/10.1111/j.1524-4725.2006.32033.x

Fong, P., Tong, H. H. Y., Ng, K. H., Lao, C. K., Chong, C. I., & Chao, C. M. (2015). In silico prediction of prostaglandin D2 synthase inhibitors from herbal constituents for the treatment of hair loss. Journal of Ethnopharmacology, 175, 470-480. https://doi.org/10.1016/j.jep.2015.10.005

Girdler, K., Cabatu, A., Olds, H., & Potts, G. A. (2026). Use of castor oil in dermatology: A narrative review. Cureus, 18(2), e103289. https://doi.org/10.7759/cureus.103289

NHS. (2023, May 3). Contact dermatitis. https://www.nhs.uk/conditions/contact-dermatitis/

Phong, C., Lee, V., Yale, K., Sung, C., & Mesinkovska, N. (2022). Coconut, castor, and argan oil for hair in skin of color patients: A systematic review. Journal of Drugs in Dermatology, 21(7), 751-757. https://pubmed.ncbi.nlm.nih.gov/35816075/

Romera de Blas, C., Vega Díez, D., Ricart Vayá, J. M., & Gómez Zubiaur, A. (2026). Complications in follicular unit excision hair transplantation: Current evidence and practical approaches. Frontiers in Medicine, 13, 1750989. https://doi.org/10.3389/fmed.2026.1750989