One such ingredient that both she and Dr. Mirmirani recommend is minoxidil, “a drug with a long and proven track record for hair growth,” says Dr. Mirmirani. “These minoxidil serums have benefits, but are often more expensive than over-the-counter minoxidil solutions or foams.” (This investment may be worth it if you’re more likely to use a serum on a regular basis, which typically yields better results.)
Also, avoid formulas that contain additives that can irritate the scalp and inadvertently cause dryness or itching, such as harsh chemicals, dyes and fragrances. Instead, look for products that have been dermatologically tested, advises Dr. Shaver.
What is the difference between a serum and a dietary supplement?
For one thing, supplements, often taken orally, can “correct certain nutritional deficiencies that may be lacking in a person’s diet,” says Dr. Mirmirani. So they may be helpful in addressing systemic causes of hair loss, such as a deficiency in certain nutrients. (For example, research has found that deficiencies in iron, vitamin D and folate may correlate with hair loss or slow hair growth.)
However, these take longer to work because supplements “must first be metabolized by the body and distributed through the bloodstream to be effective,” says Dr. Shaver. And oral supplements can have more systemic side effects and interactions with other medications, so it’s especially important to consult your doctor before taking a supplement.
“The goal of a serum is to act directly on the hair follicles by delivering compounds that can facilitate improved or optimal hair growth,” says Dr. Mirmirani. These ingredients are those not normally found in the diet, such as minoxidil and herbal compounds.
Topical serums tend to be better for “treating superficial issues like scalp flaking and hair shaft dryness because the product can be applied directly to the area that needs the serum,” says Dr. Shaver, who notes that they also produce positive effects more quickly, such as moisturizing and soothing the scalp.
How to use hair growth serums
The most important step is to test your serum before using it for the first time. “Apply the serum to a small area of the scalp for a few days to make sure it is not irritated before using it more widely,” recommends Dr. Mirmirani. “A metered approach is best.” So, be familiar with the fact that you will need to be consistent and patient with your application, as results may take some time to appear.
Apply the hair growth serum to a clean scalp (this may vary depending on the product). Ideally, you’ll do this when the hair is still slightly damp, as this “can help distribute the product throughout the scalp, making the scalp more porous and improving absorption,” says Dr. Shaver. (She notes, however, that a very damp scalp would dilute your serum and potentially make it less effective.)
