Recently, I became intrigued by questions that were asked by people who were reading my review of Viviscal, a popular hair growth supplement. Specifically, people started asking if castor oil, could re-grow hair or make it thicker? This was something that I had never heard of before but a few people stated saying castor oil was working for them. After a quick search, I discovered that sure enough, lots of websites do indeed discuss this, but, I wanted to see if there was any clinical evidence for it. So, in this review, I'm going to try to find research on castor oil and hair growth. Does castor oil really grow hair, regrow it or make hair thicker? Lets see what we can discover. Also see my review of Viviscal for more information.
What Is Castor Oil?
Castor oil, is the oil that comes from the castor bean. The scientific name for the castor bean is Ricinus communis. While castor oil has been used to treat many things over the years, for those who are old enough (thankfully I'm not one of them), some may remember it used as a laxative and/or punishment used by parents on misbehaving kids.
Castor Oil And Hair Growth: How Is It Supposed To Work?
While I could not find anything definitive on how it is said to regrow hair, some websites say castor oil helps by improving circulation to the follicles on the scalp. Castor oil does contains many substances such as vitamins and fatty acids which various websites tout as helping hair growth. Few websites though, show evidence of it.
Another theory involves inhibiting a hormone-like compound called prostaglandin D2 (PGD2). Some research finds that the scalps of bald men show higher levels of PGD2 than men who are not balding. One of the ingredients in castor oil is called ricinoleic acid (rey-sin-ole-ick acid).
At least one study has noted that ricinoleic acid can inhibit PGD2. In theory, this might mean more hair growth. Currently, human research involving ricinoleic acid and hair growth appear to be lacking. See this review of PGD2 and hair loss, for more information.
Castor Oil Hair Growth Research
I have seen before and after pictures on the internet. Some of the pictures are impressive. But, the real proof if castor oil is going to work is to see if there are any studies done on people – not test tubes studies and not lab animal studies. To see if any clinical studies exist, I searched the National Library of Medicine for these search terms:
- Castor oil hair
- Castor oil baldness
- Ricinus communis hair
- Ricinus communis baldness
- Castor oil PGD2
- Ricinus communis PGD2
I also did the same search on Google and checked ClincalTrials.gov as well. Unfortunately, I could not locate any clinical studies on castor oil helps and hair growth in people. I also looked at many websites saying castor oil improved hair loss too. None of the websites I saw showed any evidence it actually worked.
I also couldn't locate any human studies showing that blocking PGD2 in people lead to hair growth or a slowing of hair loss either. That's sad given that scientist have been talking about it.
One study has noted castor oil improved the luster of hair. In other words, when light hits the hair, it looks better. Might this “optical illusion” effect play a role the perception of some that they are growing new hair? Might it be possible that what people are seeing as “new hair” is just the oil sticking to existing hair, making it look thicker? I'm speculating of course. I have not idea either way.
Lack of evidence does not mean something does not work. It might be that interest in castor oil helping hair loss is in its infancy. I will update this review as I become aware of new research.
What About Eyebrows?
Several websites extol the benefits of castor oil for helping regrow eyebrows and eyelashes or make them thicker/fuller. Maybe it does or maybe it doesn't. All I can say is that I could not find any clinical studies that looked at this. Like anything you put near your eyes be careful with castor oil and shampoos getting in your eyes.
Do You Drink It?
Every website I saw on this issue recommended placing castor oil on the hair. Do not drink castor oil to help your hair grow. Remember, castor oil is a laxative. Every place I looked said the same thing: castor oil is said to work when a small amount is massaged into the scalp and left on for a period of time before washing it out.
How Long Does It Take To Work?
Some recommend using castor oil a couple of times a week and leaving it on the scalp for few hours before washing it out. From what I saw, if it is going to work, it might take several months of regular use before noticing any hair growth.
What Type Is Best?
Until proper human studies are done, people have two options:
1. Use the brand that people you know and trust have used and say works.
2. Start with the least expensive brand first and see if that works.
Fortunately, most brands of castor oil is not expensive.
Here is castor oil on Amazon for those who want to compare prices.
Castor Oil Shampoo
Castor oil is found in some shampoos. This might be an option for those who don't want to mess around with using straight castor oil on their hair. I'm not aware of any head-to head comparisons on which brand of shampoo might be best – or whether any of them work. These shampoos likely contain many other ingredients too. Whether these other ingredients add anything to “hair growing effects” of the product, I cannot say.
If you try one of these shampoos, look at the ingredients list. Ideally, you'd want a shampoo where castor oil is near the top of the ingredients list. The further down the list you see it, means the less castor oil is present.
Is Castor Oil + Coconut Oil Better?
It appears no clinical studies have investigated whether adding coconut oil will improve the hair growth effects of caster oil. It may or may not.
Castor Oil Side Effects
I'm not aware of any negative side effects from massaging castor oil into the scalp. Other than it maybe smelling bad, it appears to be safe. One case study noted a “contact allergy” when it was placed on the skin. Others have also noted allergies to castor oil too.
I don't know how common castor oil allergies are, so just in case this happens in others, for those who have not used it before, it may be wise to rub a small amount on to the skin for a few days to see if you personally have any negative reaction to it.
Some may have heard that the castor bean is the source of ricin, a deadly poison. While this is true, there is no ricin in castor oil.
If anyone has any thoughts or tips on how to use castor oil best, please leave a comment below.
Does Castor Oil Work?
I have no idea of it works or not. Given that several people have told me castor oil was helping their hair growth, I was disappointed to see no human clinical trials to confirm or deny this. Is that because you can't patent castor oil like you can patent a hair growth drug? Maybe. As research on this topic this eventually changes. I'll update this review.
As this paper points out, there is some rationale that PGD2 might lead to hair loss in some people. Given that ricinoleic acid -a component of castor oil – can block/inhibit PGD2, does appear to lend some evidence to its effects. To know for sure though, we will need human research. For what it's worth, I think hair loss is more complicated than simply blocking one chemical. The good news for those who want to try it is that castor oil isn't expensive and likely doesn't have any bad side effects when applied topically.