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What is minoxidil?
Minoxidil (brand name Rogaine) is an FDA-approved hair loss treatment applied to the scalp twice a day to slow or stop the progression of male pattern baldness and thinning hair. “Minoxidil is thought to help increase circulation in the scalp, which can help improve nutrients and ingredient delivery to the hair follicle,” says Tsippora Shainhouse, MD, FAAD, a board-certified dermatologist in Beverly Hills, California. “But its mechanism of action is not entirely clear.”
- Minoxidil comes in two forms: foam (aerosol) and liquid (topical solution). It also comes in two concentrations: 2% and 5%.
- All versions have pros and cons.
- Liquid minoxidil may cause side effects like irritation because it contains an ingredient that the foam versions lack.
It’s available over-the-counter as a liquid (sometimes called a topical solution) or foam (sometimes called an aerosol). Both are currently available in two different strengths: 2% and 5%.
To maintain results, minoxidil must be used continuously. Four months is generally needed to see results. If you stop using the medication, the new hair growth may reverse, and hair loss will continue.
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Minoxidil foam vs. liquid
When choosing between minoxidil foam or liquid, these considerations may come into play.
Allergies or sensitivities
Some men might experience an allergic reaction when using the liquid form of minoxidil. That’s because it contains propylene glycol, which is often the cause of allergic reactions or irritation (Friedman, 2002). The foam version of minoxidil does not contain propylene glycol. However, it’s still possible to be allergic to some of the other ingredients in the foam, like minoxidil itself (Badri, 2020).
Look and feel/absorption
Minoxidil liquid may cause your hair to feel or look somewhat greasy. If that’s the case, the foam version may be better for you. “Foam may absorb more quickly, so that skin and hair appear less greasy and have less oily residue,” says Shainhouse. “It’s less likely to drip where you don’t want it, like the face.”
Ease of use
The density of foam and the precision of liquid (which is applied with a dropper) both have benefits and drawbacks. “Foam is easier to apply to larger areas with significant balding or thinning hair,” says Shainhouse. “But the liquid form of minoxidil may be easier to apply to the scalp, particularly if you have long hair near the application area, which may catch some of the foam before it makes it to your scalp.”
Men vs. women
Minoxidil 2% topical solution and 5% topical foam are FDA-approved for use by women. However, the 5% topical solution is only FDA-approved for use in men, and it is considered off-label use when used by women.
Why? “That’s just how Rogaine currently has the FDA approvals, and it would be very costly and time-consuming for them to go through the clinical trials to approve the 5 percent minoxidil solution for women,” wrote Dr. Eric Schweiger, a New York City board-certified dermatologist, and hair transplant surgeon, on hairloss.com. “I use both for women in my practice, depending upon the specific hair loss, sensitivity, and scalp situation.”
One review of 17 studies on minoxidil use by women with female pattern baldness found no difference in effectiveness between 2% and 5% formulations. But the researchers said more study was needed (Van Zuuren, 2016).
Which is best for me?
Should you use minoxidil 2% or 5%? Liquid or foam?
Studies show that the higher concentration of minoxidil is more effective than the lower one. In one study published in the Journal of the American Academy of Dermatology, men were assigned to three different groups: 5% minoxidil, 2% minoxidil, or placebo. Men using 5% minoxidil had 45% more hair regrowth than the 2% group (Olsen, 2002).
But in terms of whether foam or liquid is more effective, “the verdict is still out,” says Dr. Lawrence Barnard, DO, a hair restoration surgeon at Maxim Hair Restoration in New York City. “The liquid form is often used because it’s believed to be more effective due to increased absorption, but research is insignificant and far from proving this.”
Some researchers also theorize that, because the liquid causes irritation and dermatitis more frequently than foam, it causes blood flow and growth factor migration that may stimulate hair growth, making it the more potent of the two formulations, explains Barnard. But right now, that’s just a theory.
“The reality is that it comes down to user preference,” says Barnard, who has found that his patients tend to prefer foam. “If you have highly sensitive skin, then you may find that minoxidil foam is the better option, as it’s less likely than its liquid counterpart to spread to peripheral locations. Due to the lack of sufficient evidence as to which form has higher efficacy, we recommend the foam to avoid dermatitis. It seems to be more comfortable and has less of a negative impact on your aesthetic.”