The causes of hair loss run the gamut, according to the American Academy of Dermatology Association, from age and poor diet, to significant weight loss, chronic iron deficiency, thyroid disorders, childbirth, and more.
In the United States, the most common type of hair loss, androgenetic alopecia, commonly known as male or female pattern hair loss, is hereditary and affects more than 50 million men and 30 million women, according to the National Institutes of Health.
Given that hair loss is so common, the marketplace can seem crowded with products promising to help.
The first step to treating hair loss, though, is to work with a health care provider to identify the cause, according to Dr. Jennifer Ashton, ABC News chief medical correspondent and a board-certified obstetrician and gynecologist.
Once a root cause is identified, there are natural, cost-effective remedies that may help stop hair loss and even boost hair growth.
Here, Ashton breaks down six of the most scientifically proven natural remedies for hair loss.
What to know before trying a natural remedy: Ashton notes that the natural remedies are topical solutions, meaning they should be applied to the skin and scalp, and not ingested. Because applying the remedies could potentially cause scalp irritation, Ashton suggests testing the solution on a small patch of skin for a day or two and observing the results before applying it to the scalp.
She also says each remedy below is one that should be used every other night or every two to three days, not daily. Also, patience is required, as it could take as long as three to six months to see any results. There are also FDA-approved medications available for hair loss. Talk to your doctor to see if you may be eligible.
1. Coconut oil
Coconut oil has been shown in research to potentially help prevent hair loss.
While it is more a preventive option than a remedy for regrowing hair, Ashton said coconut oil – which comes both in liquid and solid forms – is a low-risk option that she loves.
"There's very limited data that shows a dramatic improvement with hair growth or hair thickening with a coconut oil," Ashton said. "But ... you always have to say to yourself: risk versus benefit. This is incredibly low-risk. There may not be a benefit there, but it's certainly not going to do harm."
Pro tip: Ashton suggests also using coconut oil as a moisturizer, noting that it is safe to be absorbed into the bloodstream and can be used "from head-to-toe."
2. Rosemary oil
At least one study has found that rosemary oil is similarly effective as the over-the-counter hair-growth medication minoxidil – commonly sold under the brand name Rogaine – in promoting hair growth.
The oil, which is extracted from the rosemary plant, can be directly applied to and massaged into the scalp, according to Ashton.
Pro tip: Ashton suggests vigorously massaging rosemary oil into the scalp to increase absorption and blood flow.
3. Peppermint oil
Peppermint oil has been shown to stimulate hair growth in animal studies by working to increase blood flow to the scalp.
"Peppermint oil vasodilates," Ashton said. "[That] means it takes the blood vessels and makes them larger. When you make a tube larger and you're talking about a blood vessel, that increases blood flow. Menthol, eucalyptus, peppermint absolutely can do that."
Ashton said peppermint oil needs to be diluted with another oil, after which it can be applied and massaged directly into the scalp.
Pro tip: Ashton recommends washing your hands thoroughly after using peppermint oil, to avoid skin irritation.
4. Red ginseng
Red ginseng is a widely-used herbal remedy that has also been shown in studies to improve hair growth in mice.
"There is some improvement in thickening [hair], in transitioning the hair follicle from the resting phase to the more active phase," Ashton said of using red ginseng. "Again, pretty low risk, and may have some benefit."
Pro tip: Ashton says that red ginseng also needs to be diluted with another oil, or used sparingly in droplet form on the scalp.
5. Onion juice
Onion juice has been shown in studies as well to promote hair growth in people.
It's said to work because of its sulfur content, which is said to help strengthen hair, reduce inflammation and hydrate the scalp.
Onion juice can be rubbed directly into the scalp on its own.
Pro tip: Be aware that onion juice carries with it a potent odor, and make sure to wash your hands thoroughly after use, recommends Ashton.
6. Scalp massage
Studies show that simply massaging your scalp can help increase the thickness of your hair.
The technique works by helping to boost blood flow to the scalp, according to Ashton.
"There are a lot of different instruments out there," Ashton said of scalp massager options. "They're inexpensive. You can order them online or find them in in some drugstores."
Pro tip: While there are many scalp massager products on the market, Ashton says using your own fingers to massage your scalp is equally effective.
BONUS: What ingredients to look for in hair products
Just like packaged foods have nutrition labels that list their ingredients, hair-care products do as well.
While those hair-care product ingredients may be intended to help support hair growth or treat hair loss, they can also potentially cause hair loss, as well as affect your overall health, according to Ashton.
"Anything you put on your skin, including your scalp, will be absorbed into your bloodstream," she said. "So it really is a good idea to make sure that those ingredients are as clean and low in chemicals as possible."
The first ingredient to look for in a hair-care product, according to Ashton, is alcohol.
"It's oftentimes one of the first three ingredients, but it does real damage to your hair," Ashton said of alcohol. "It literally dries out the hair, makes it subject to breakage, and, ultimately, it can also dry out your scalp, depending on where you're applying it."
She continued, "So that's something that's in almost every hair product, but you want to try to pick one that either doesn't have it at all or doesn't have it in the first three ingredients."
On the other hand, beneficial ingredients to look for in hair-care products include caffeine, menthol or mint, according to Ashton. She noted that those ingredients will increase blood flow when applied to the scalp, which in turn helps overall scalp health.