However, many people swear by these vitamins to help support hair health overall—and if you do find a formula that gives you noticeable results (i.e., a longer mane), your body hair can technically join the party, too.* “Oral supplements cannot solely target one area of the body—only topical products can do that,” says Yadav. “If you take a hair growth [vitamin] by mouth, it will affect all of your hair follicles.” Certified trichologist William Gaunitz, FWTS, founder of Advanced Trichology, agrees: "Internal hair growth supplementation, no matter what, will impact the entire body in one way or the other. There’s no changing the systemic impact," he says.
Essentially, there’s no way these nutrients and bioactives know that you want lush locks on your head but to leave your arms and legs alone. How could they?
Here’s the thing, though: These vitamins are not going to make hair suddenly appear in areas you don’t have hair to begin with. For example, if you don’t already have facial hair, taking a hair growth supplement will not magically sprout a stache. “New facial hair growth can occur when hormone levels are disrupted; vitamin supplements likely won't affect your hormones (though it's always worth seeing a physician and naturopath before starting a new vitamin regimen, if you're concerned),” Yadav explains.
However, if you do invest time and money in hair removal (waxing, sugaring, shaving, etc.), you should know that these supplements can technically promote hair growth in these areas.* "If you were nutritionally [insufficient] and the hair growth vitamin is supplying you appropriate nutrition systemically, it is possible to increase body hair that was affected by nutritional [gaps] prior,"* says Gaunitz.
At the same time, it's not like you're going to experience an unnatural amount of body hair. "When you are utilizing hair growth supplementation, the best possible outcome is that you have the fullest amount of hair that you would have had naturally," Gaunitz adds. Meaning, your body already had the capacity to grow that much hair—the vitamins may just support the appropriate amount of nutrition to do so.*
Again, you can’t expect a formula to promote fuller, stronger strands on your head without targeting the other follicles on your body. But as Yadav adds: “They can also promote longer and stronger fingernails—so it's not all bad!” (and let's not forget the skin benefits, mind you).*