Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 12/11/2020
Losing your hair can be a stressful, frustrating experience. It’s also a common one. According to the American Hair Loss Association, about two thirds of American men experience some degree of hair loss by age 35, with 85 percent experiencing significant thinning by the age of fifty.
If you’ve searched online for information about preventing hair loss, you may have come across articles and how-to guides recommending onion juice as a natural treatment for baldness.
Many natural health enthusiasts recommend onion juice as an alternative to medications for hair loss. Although it’s popular in some circles, onion juice hasn’t been widely studied and not a lot of information is available about its effectiveness.
Below, we’ve dug into the science behind onion juice as a natural treatment for hair loss. We’ve also explained how and why hair loss happens, including the genetic and hormonal factors that may cause you to experience thinning and baldness.
Finally, we’ve listed other treatments that you may want to consider if you’re starting to lose your hair, including several FDA-approved, science-backed medications.
Onion juice has long been a favorite of natural health enthusiasts, and for good reason: onions are full of important nutrients and, when eaten as part of a balanced diet, offer a diverse range of health-related benefits.
For example, onions are rich in dietary flavonoids — a group of important antioxidants that may be related to a reduced risk of disease. They’re also rich in dietary fiber and vitamins, such as vitamin C and important B vitamins.
Despite these health benefits, there isn’t much research on the effects of onions or onion juice on hair loss. Very few studies have been carried out, with the research that is available small in scale and far from ideal in terms of quality.
To treat hair loss effectively, it’s important to understand how and why hair loss happens in the first place.
Contrary to popular belief, hair loss isn’t caused by wearing a hat, overusing shampoo or other common myths. Instead, male pattern baldness — the specific type of hair loss that affects men — is caused by a genetic sensitivity to the hormone dihydrotestosterone, or DHT.
DHT is a byproduct of testosterone — an important male sex hormone that your body produces in order to give you male characteristics. Your body converts a small amount of testosterone to DHT via an enzyme called 5 alpha-reductase.
If you’re genetically susceptible to male pattern baldness the excess DHT that’s produced by your body may bind to your hair follicles. This causes the follicles to gradually shrink, weaken and, over time, stop producing new hairs.
Not all men are equally sensitive to DHT. Some men have hair follicles that are barely affected at all, with little to no noticeable hair loss even in their 40s and fifties. Others are highly sensitive to DHT, with significant, noticeable hair loss in their 20s and thirties.
We’ve explained the relationship between DHT and hair loss in more detail, as well as how your genetics can factor into the equation, in our full guide to DHT and male pattern baldness.
Because DHT is the primary hormone responsible for male pattern baldness, the most effective hair loss treatments generally work by either blocking the effects of DHT at a local level (in your scalp specifically) or at a systemic level (throughout your entire body).
Others work by increasing the supply of blood to your hair follicles to promote healthier, thicker hair growth.
We’ve talked about these treatments in more detail further down the page. You can also learn more about them in our guide to the current options for treating and reversing hair loss.
Although onion juice is often recommended online as a natural treatment for hair loss, scientific evidence to back up its purported benefits is hard to come by.
For example, one study from 2002 is often provided as evidence that onion juice is effective at preventing hair loss.
In the study, a group of 23 people with a form of hair loss called alopecia areata were given an onion juice treatment and told to apply it two times per day. A second group of 15 people were given a treatment consisting of tap water and told to do the same thing.
The researchers monitored the progress of both groups over the course of the study. After six weeks, 86.9 percent of the people in the onion juice group showed signs of hair regrowth, with only 13 percent of people in the tap water group experiencing regrowth after eight weeks.
At first glance, this study looks like great evidence for onion juice as a hair loss treatment. After all, most of the people in the onion juice group experienced hair regrowth, versus just a fraction of the people in the total number of people in the tap water group.
However, after looking at things more closely, it’s clear that this study really doesn’t prove much when it comes to preventing male pattern baldness.
First, the study is very small, with just 23 people in the onion juice group and 15 in the tap water group. Second, the patients that took part in the study were male and female, meaning the total number of men in the study is even smaller than it first appears.
Third, the patients were affected by a type of hair loss called alopecia areata, which is believed to be an autoimmune disease. As such, even if onion juice is effective for regrowing hair that’s lost due to alopecia areata, this doesn’t mean that it’s a treatment for male pattern baldness.
In short, although the study is interesting, it’s far from definitive proof that onion juice is actually effective at preventing, treating or reversing hair loss caused by male pattern baldness.
As for other research, there isn’t any. Although there’s a lot of scientific evidence to back up the other health benefits of onions, no large-scale, reputable research has actually looked at onion juice as a treatment for male pattern baldness.
While there’s little evidence that onion juice is effective at preventing hair loss, there are several proven, science-backed treatments that you may want to consider using if you’re starting to lose your hair:
F. An FDA-approved medication for male pattern baldness, finasteride works by inhibiting the effects of 5α-reductase — the enzyme that’s responsible for converting testosterone into DHT.
Numerous studies have found that finasteride helps to prevent hair loss caused by male pattern baldness. Some have noted that men who use finasteride experience regrowth in certain parts of the scalp — a topic we’ve discussed in our guide to finasteride results.
We offer finasteride online, following an online consultation with a healthcare provider to determine if a prescription is appropriate.
M. A topical treatment, minoxidil has been approved by the FDA to treat hair loss and help regrow hair. It comes in liquid or foam form and is designed to be applied to the areas of your scalp that are affected by hair loss.
Like finasteride, minoxidil has been proven effective in numerous studies, with research showing that results usually take around three to six months.
Ketoconazole shampoo. Shampoo containing the topical antifungal ketoconazole may help to improve hair growth and stop hair loss. In fact, one study found that it performed similarly to minoxidil as a treatment for stimulating hair growth.
Our guide to ketoconazole shampoo and hair loss goes into more detail about what you can expect from ketoconazole shampoo as a hair loss treatment.
Many other treatments, such as saw palmetto and biotin, may also help to prevent hair loss and stimulate the growth of new hair. However, there isn’t as much research about these treatments available as there is for FDA-approved medications such as finasteride and minoxidil.
Despite popularity in natural health circles, there’s no large-scale scientific proof to suggest that onion juice helps to treat male pattern baldness.
If you’re starting to lose your hair, it’s generally best to stick with FDA-approved treatments such as finasteride, minoxidil or both. These medications have undergone large-scale testing for both efficacy and safety, making them reliable choices for protecting and restoring your hair.
For further information about detecting and stopping hair loss, check out our guide to the early signs of balding. It covers what to look for if you’re worried about hair loss, as well as the steps that you can take to stop hair loss and protect your hairline.
Insider tips, early access and more.