castor oil for hair: A Survey of Research
Someone recently asked me a fascinating question after reading my review of Viviscal, a popular hair growth supplement: Does castor oil have hair growth or can make hair thicker? I had never thought about this question before, but I found some people online saying that castor oil has these effects.
I found that there are indeed many websites discussing this issue, but I wanted to know if there is enough clinical evidence to prove the effect of castor oil. So in this article, I decided to find out if there is any research on the hair growth effect of castor oil. Does castor oil really have the effect of growing and strengthening hair? Let’s see what we can find. Of course, if you are interested in the Viviscal supplement mentioned above, here is my previous review of Viviscal supplement.
What is castor oil?
Castor oil is an oil extracted from the castor bean, the scientific name of which is Ricinus Communis . It has long been used to treat a variety of ailments, but if you’re old enough (thankfully I’m not), you might remember it being used as a laxative and as a punishment for disobedient children.
Castor Oil and Hair Growth: What Benefits Might It Have?
Although I haven’t found any definitive articles to determine whether it works, some websites say that castor oil works by promoting lymphatic circulation in the scalp. Castor oil does contain many nutrients, such as various vitamins and fatty acids, and a lot of websites use this to brag about the hair growth effect of castor oil, but few websites actually provide evidence to prove its effectiveness.
Another theory is based on the inhibition of a hormone-like substance called prostaglandin D2 (PGD2). Some studies have found that the scalp of bald people has higher levels of PGD2 than the average person . Ricinoleic acid, a component of castor oil, can inhibit the action of PGD2.
At least one article suggests that ricinoleic acid can inhibit the effects of PGD2 . In theory, inhibiting the effects of PGD2 should mean hair growth. However, there are still too few studies based on human experiments on the effects of ricinoleic acid on hair growth. If you are interested, I found a review on PGD2 and hair loss , which can help you learn more about the effects of PGD2.
Study on the Hair Growth Effect of Castor Oil
Regardless of its theoretical basis, the best way to prove whether castor oil is effective is to see if there is any relevant human research – in vitro studies and animal experiments do not count. To find relevant research, I searched the National Library of Medicine for the following keywords:
- Castor Oil Hair
- Castor Oil for Baldness
- Ricinus Communis Hair
- Ricinus Communis Baldness
- Castor Oil PGD2
- Ricinus Communis PGD2
I also searched Google and ClinicalTrails.gov , hoping that these keyword searches would yield some evidence based on human studies published in medical journals.
Unfortunately, I haven’t found any evidence that castor oil can help promote hair growth. I’ve also seen on many websites that castor oil can help prevent hair loss, but I haven’t found any evidence that it can help prevent hair loss.
I can’t find any human studies that show blocking PGD2 on the scalp can restore hair growth or alleviate hair loss. It’s sad that there are no studies to prove that the theory is correct.
I did find an article that said castor oil can improve the color of hair . In other words, when light hits your hair, it looks prettier. Maybe this “optical illusion” phenomenon is what people think of as hair growth? Maybe the “new hair” people see is just the castor oil sticking to the hair and making it look thicker? I’m just speculating, and since there’s no scientific research , I have no idea.
The lack of experimental evidence doesn’t mean it doesn’t work, but perhaps the popularity of using castor oil for hair growth isn’t strong enough for the scientific community to study it properly. If I find new research, I’ll list it here.
So how does it work for eyebrows?
As I was writing this, I also saw some websites touting that castor oil can also promote the growth of eyebrows and eyelashes, and make them fuller and thicker. As with the hair research above, I couldn’t find any relevant research, so let them say what they want.
Do you drink castor oil?
All the websites I looked at recommended putting castor oil on your hair. Do not try to drink castor oil to help your hair grow. Remember, castor oil is a laxative. All the websites I found said the same thing: Put a small amount of castor oil on your hair, massage it into your scalp, and wait a while before rinsing it off.
How long does it take for it to take effect?
Some websites recommend using castor oil a few times a week, leaving it on for at least a few hours before washing it off. From what I’ve heard, you may need to use it for a few months before you see noticeable growth.
Which castor oil is best?
Considering that there are no relevant human trials to prove that castor oil can relieve hair loss or promote hair growth, I don’t know what criteria you use to judge which brand is good – such as cold extraction , organic extraction, etc.
As I said before, until there are enough human studies proving its efficacy, you have two options:
- Use a brand that someone you know is using, has seen results with, and recommended to you.
- Start with the cheapest brand and use it for a while to see if it works.
Fortunately, most castor oils are inexpensive.
Here is a link to castor oil from Amazon if you want to compare prices .
Castor Oil Shampoo
There are also a number of shampoos that contain castor oil. For those who don’t want to end up with a mess of castor oil all over their hair, castor oil shampoo may be a good option. I haven’t found anyone who says that one brand of castor oil shampoo is better than another – or to put it another way, I haven’t heard anyone say that any one brand works. These shampoos all contain a lot of other ingredients, and it’s possible that these ingredients, besides castor oil, will help hair growth, but I’m not sure if that’s the case.
If you’re planning to try this shampoo, take a look at the ingredients list first. Ideally, you want a shampoo that lists castor oil near the top of the list. The lower it is on the list, the less castor oil it contains.
Side Effects of Castor Oil
Since I can’t find any literature on castor oil’s effects on humans, I don’t know if applying it to your scalp will cause any side effects. Aside from the fact that it makes you want to throw up, it’s pretty safe. There is one case study that says castor oil can cause a ” contact allergic reaction ” if applied to the skin . I found another case report of an allergic reaction to castor oil .
I’m not sure how common an allergic reaction to castor oil is, so to prevent this unpleasant ailment from happening to you, if you haven’t used such products before, apply a small amount to your skin for a few days before using a shampoo containing castor oil to see if you have an allergic reaction to it.
Some of you may have heard that ricin—a deadly poison—is also extracted from castor beans. While this is true, it is scientifically and factually proven that castor oil does not contain ricin .
If you are using castor oil and it works well for you, please leave a comment below so everyone can learn how to use it correctly.
Does castor oil work?
I have no idea if it works. A few people have told me that castor oil worked on their hair, but I’m disappointed because there is no clinical evidence to prove it works, so I can’t say for sure. But it’s possible that you can’t patent castor oil products like you can patent hair growth drugs, so major companies are researching more profitable hair growth drugs instead of proving castor oil’s hair growth effect – clinical trials are also very expensive and time-consuming. Anyway, if there are any new discoveries about castor oil in the future, I will update here.
As this article points out , there are some theories that PGD2 may cause hair loss in some people. Considering that ricinoleic acid, a component of castor oil, can block/inhibit the effects of PGD2, it is possible that castor oil may have some anti-hair loss effects. However, to fully confirm this, we need more human data. Regardless, I think hair loss is a very complex process, and blocking the effects of just one compound is unlikely to reverse the entire process. The good news for those who are eager to try, however, is that castor oil is not expensive and has no side effects when used properly.
