It’s one of the first rec­om­mend­ed reme­dies when nat­u­rals com­plain of thin strands or weak edges; “Girl just rub it with some cas­tor oil!” And many women swear by the thick­en­ing and strength­en­ing prop­er­ties of cas­tor oil, but what if it’s not sci­en­tif­i­cal­ly proven! A detailed arti­cle from explains why cas­tor oil does not actu­al­ly thick­en strands of hair

“…it is bio­log­i­cal­ly impos­si­ble for the phys­i­cal hair strand to become thick­er after it has emerged from the scalp. There­fore, it should make sense that prod­ucts applied direct­ly to the hair that promise to increase the thick­ness can only deliv­er the illu­sion of actu­al hair thick­ness. In order to phys­i­cal­ly grow thick­er strands of hair, you would have to address the prob­lem at the root (pun intend­ed)…”

But what about the many nat­u­rals who swear by incred­i­ble results from cas­tor oil? 

“Improved hair den­si­ty due to a cas­tor oil treat­ment could be attrib­uted to the lubri­cat­ing of the scalp with an oil known to have anti-inflam­ma­to­ry and antibac­te­r­i­al prop­er­ties, which can help clear up bac­te­r­i­al infest­ed fol­li­cles. This can most like­ly be achieved with oth­er oils such as rose­mary or tea tree oil. In addi­tion, it is often encour­aged to light­ly mas­sage the oil into the scalp. A scalp mas­sage alone could pos­si­bly stim­u­late blood cir­cu­la­tion, which may help the flow of nutri­ents in the papil­la. In this case, results would not be lim­it­ed to the use of cas­tor oil, but any prod­uct asso­ci­at­ed with a scalp mas­sage or scrub. In my opin­ion, this all comes down to a per­son­al pref­er­ence.”

Blog­ger and biol­o­gist Jc of the Nat­ur­al Haven also cred­its cas­tor oil’s stick­i­ness for its per­ceived thick­en­ing qual­i­ties.

“…cas­tor oil per­haps can stick to hair more firm­ly than most oils and there­fore cre­ate an illu­sion of thick­ness. Any­one who has used it will note how thick and vis­cous it is. It is almost like a soft glue and tends to stay put and not move when applied. It does not trans­fer eas­i­ly either, which means that it can attract small par­ti­cles of dust and lint which may also add to the illu­sion of thick­ness.”

Hmm­mm.… Well we’re cer­tain­ly not going to ditch our cas­tor oil! It is still an incred­i­ble oil with great seal­ing and strength­en­ing abil­i­ties.

Ladies, what are your thoughts?

Black Girl With Long Hair

Leila Noel­liste, founder of Black Girl with Long Hair (April 2008). Social media, pop cul­ture and black beau­ty enthu­si­ast. bell hooks’ hair twin…

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10 Comments on "Science Confirms Castor Oil Does Not Thicken Hair Strands"

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It works!

Nicole Hunter

I don’t care what the sci­en­tist is talk­ing about. Just like doc­tors don’t know every­thing and even their tests can be wrong, so can the sci­en­tist!


Oh well, it solved my bald edges issue so i’m still using it. Before i start­ed using JBCO my hair line was reced­ing rapid­ly. I gen­uine­ly believe this stuff stim­u­lates hair growth.


Yes, but peo­ple don’t use cas­tor oil to thick­en their indi­vid­ual hair strands, but to restore thin edges (increase the *num­ber* of indi­vid­ual hair strands). And even this post admits that by killing bac­te­r­i­al growth on your scalp, it allows dor­mant fol­li­cles to pro­duce hair and accom­plish just what these ladies are look­ing for. :)


Well, what I DO know for sure is that JBCO was the only thing that helped restore my edges so I’m for­ev­er a fan!


Sci­ence is a dis­course like any­thing else. One day sci­en­tists know some, the next day they learn some­thing else. Sci­en­tists don’t have all the answers.


I have been into nat­ur­al hair sites for 4+ years and have nev­er heard that black Jamaican cas­tor oil made strands thick­er; I not­ed on my research that it help regrow and retain your edges, aaar­rrgggh­hh, what’s up with that head­line!


Yeah, I’ve nev­er heard that either. I’ve heard that it stim­u­lates hair growth and I believe that to be true. I’ve been using it as a face mask to seal in mois­ture on my skin and my sparse eye­brow hairs have got­ten longer. It’s strange, but now they look more full, so I’ll take’em


Well I am hap­py you are shar­ing this info because *cough cough* some major hair brands that cater to us — MMMMM WHY YOU LYING?! Cas­tor oil is great for hair though, no doubt.

I fig­ured this out back in 2009 that it doesn’t thick­en strands, it just coats it. Sim­i­lar­ly to the tex­ture and stick­i­ness of min­er­al oil also. It attracts lint and oth­er par­ti­cles to the ends to look thick­er. The more you rub in, the more par­ti­cles twist and attach to your hair caus­ing an illu­sion. Hen­na also sticks the the hair too and stays bc it’s like a clay. Once you stop using hen­na, you no longer have that red­dish clay after col­or and the thick­ness also fades too. So I just stuck with using sesame, peanut, or any oil… Read more »