Minoxidil foam or liquid: which formula should you choose?

The liquid solution has been around since 1984. It’s the original formulation, the one used in all those major clinical studies that proved minoxidil actually works for androgenetic alopecia. Decades of proven results speak for themselves.

The foam arrived later, specifically designed to solve a problem dermatologists kept seeing: skin irritation from propylene glycol, wich is in the liquid version.

But choosing between them isn’t just about whether your scalp gets irritated. Your skin type matters, yes, but so does your hair length, your daily routine, your budget, and, honestly, whether you can stick with a treatment that requires months (sometimes years) to show real results.

Because here’s the thing: minoxidil is a commitment. You’ll need at least several months to see any difference, and often years to maintain it. This is exactly why picking the right formulation matters so much. A treatment you abandon after three weeks because it’s irritating your scalp or making your hair look greasy? Completely useless. Far better to choose something you’re actually comfortable using from day one.

The mechanism at work in your follicles

The transformation of minoxidil

Minoxidil doesn’t work the moment you apply it to your scalp. It’s what we call a prodrug, essentially, it needs to be transformed into something else before it becomes effective. This conversion happens right inside your hair follicles, thanks to an enzyme called sulfotransferase.

This enzyme converts minoxidil into minoxidil sulphate, which is the actual active form. And here’s where it gets interesting: the activity of this enzyme varies massively from person to person.

Research shows that minoxidil sulphate is 14 times more potent than minoxidil at stimulating hair growth. What does this mean in practice? Well, if your body produces plenty of sulfotransferase in your follicles, you’ve got a decent chance of responding well to treatment. If you produce very little, you’ll probably be disappointed with the results, regardless of whether you choose foam or liquid.

There are tests that can predict your response to minoxidil by measuring this enzymatic activity, with a sensitivity of 93% and a specificity of 83%.

The effect on the hair cycle

Once it’s activated, minoxidil sulphate affects the hair cycle in several ways. It shortens the telogen phase, that’s the resting phase when hair isn’t growing, from 20 days down to just 1 or 2 days in animal studies. What happens then? Dormant follicles wake up much faster and enter anagen, the active growth phase.

It also extends this growth phase, which means longer, thicker hair. On top of that, minoxidil increases production of VEGF (vascular endothelial growth factor) sixfold, improving blood flow around the follicles.

How long before you see results? You’ll need patience. The first visible changes typically appear after a minimum of 8 weeks. That’s how long it takes for your follicles to respond to the signal, enter the growth phase, and for new hairs to emerge from the scalp.

Best results usually show up between 6 and 12 months of continuous use. Clinical data suggests about 3 out of 5 patients see improvement after 6 months, which is actually quite encouraging.

Worth remembering: Whether you choose foam or liquid doesn’t change how minoxidil works. But it does affect how well the minoxidil penetrates your skin and reaches those follicles. Just as importantly, it determines whether you can actually tolerate the treatment long enough to see any benefits.

The liquid solution: effective but not always comfortable

Composition

Minoxidil liquid solution remains the scientific gold standard. Most of the major clinical studies validating treatment for androgenetic alopecia since 1984 used this formulation.

The solution contains three main components:

• Minoxidil (the active ingredient)
• Ethanol (alcohol)
• Propylene glycol

The last two aren’t just fillers, they’re there to dissolve the minoxidil and help it pass through the skin barrier. Propylene glycol, in particular, helps minoxidil penetrate down to the hair follicles.

About 1.4% of topically applied minoxidil actually penetrates normal skin. Sounds small, doesn’t it? But it’s more than enough to get results whilst limiting how much enters your bloodstream.

Proven effectiveness

The data supporting the liquid solution is robust. Over a 5-year follow-up period, studies show that 2% minoxidil produces a peak in hair growth as early as the first year in men, with effectiveness maintained in subsequent years. The 5% version works even better.

The solution works on the entire scalp, from the frontal area right through to the crown. The main advantage? Price. It’s generally more affordable than foam. The fluid texture also allows for very precise application to specific areas, which is particularly useful if you’ve got short hair or localised thinning.

Daily drawbacks

Now for the less pleasant bit: this same fluid texture can cause real problems with daily use. Many people complain about the greasy or sticky feeling that lingers after application. As it dries, the solution can leave crystalline residue on your scalp, doesn’t affect effectiveness, but it’s frankly unpleasant. The liquid also tends to drip easily, especially if you’ve got longer hair or you’re applying it to your temples.

Irritation is the real issue with the liquid solution:

• About 7% of people using the 2% solution report itching, dryness, redness, or flaking
• This percentage goes up with the 5% version, which contains more propylene glycol
• Studies show that 11% of patients develop allergic contact dermatitis with alcohol-based formulations

One clinical trial measured scalp hydration after 30 days of use. The result? Alcohol-based formulations significantly reduced skin hydration, with an average decrease of 3.28. Alcohol and propylene glycol both have a pronounced drying effect, which explains why some patients stop treatment despite it actually working.

Who is the liquid solution for?

The liquid solution suits patients without specific skin sensitivities who want an economical treatment and need very precise application. If you’ve got short hair, a limited application area, and your skin handles alcohol-based products well, the liquid solution makes sense.

Foam: comfort and efficacy combined

A redesigned formulation

Minoxidil foam was specifically developed to address the irritation caused by propylene glycol. Its thermosetting, hydroethanolic formulation uses cetyl and stearyl alcohols instead of propylene glycol. The result? Significantly better skin tolerance whilst keeping the active ingredient working just as well.

Technical advantages

The foam format offers a real technical advantage. Unlike a solution that stays liquid, the foam concentrates the active ingredient at the interface between the vehicle and your skin. This helps minoxidil penetrate into the follicles more effectively.

Laboratory studies demonstrated this rather dramatically: in an animal model (hamster ear), the 5% foam generated 5 times greater minoxidil absorption than the 5% solution after 2 hours of application.

Another significant point is systemic absorption. With the 5% foam (1g applied twice daily), absorption into the bloodstream is roughly half that seen with the 5% solution (1cc twice daily). This reduces the risk of systemic side effects, though these remain rare with topical formulations anyway.

Proven efficacy

But does the foam work as well as the original solution? Phase III clinical trials give us a clear answer.

In a study of 113 women with androgenetic alopecia, researchers compared the 5% foam applied once daily to the 2% solution applied twice daily. At 24 weeks, the increase in hair count was virtually identical:

• 5% Foam: 23.9 hairs/cm²
• 2% Solution: 24.2 hairs/cm²

The foam proved non-inferior to the solution, with a major bonus: significantly fewer side effects.

In men, a 16-week study of 352 participants showed that the 5% foam increased hair count by 13.4% in the target area, compared to only 3.4% with placebo.

Superior tolerability

Regarding tolerability, the numbers speak for themselves. After 52 weeks of treatment with foam, only 5% of patients reported scalp irritation symptoms. That’s considerably less than the 7 to 11% seen with alcohol-based solutions.

The impact on skin hydration is similar: propylene glycol-free formulations significantly improve scalp hydration (an average increase of 9.74 after 30 days), whereas alcohol-based solutions make it worse.

The daily experience

The difference is noticeable straight away. The foam has a light texture that spreads easily, even through longer hair. It dries quickly without leaving any greasy or sticky residue. Your hair stays manageable after application.

For many patients, especially those who gave up on the liquid solution because it was too uncomfortable, this changes everything. Studies also show that a single daily application of the 5% foam is enough to achieve results comparable to two daily applications of the 2% solution. This simplifies treatment considerably and improves long-term compliance.

One particularly interesting study followed patients who didn’t respond to the conventional 5% minoxidil solution and switched to a propylene glycol-free foam. Result: 70% showed observable improvement on clinical examination and microscopy, and an additional 22% showed improvement only visible under microscopy.

This suggests that some “non-responders” to minoxidil aren’t actually non-responders at all, they just couldn’t tolerate the liquid formulation.

Who is the foam for?

The foam particularly suits patients with a sensitive scalp or a history of skin irritation. Those who’ve already tried the liquid solution and couldn’t get on with it. People with longer hair for whom liquid application is awkward. And anyone who values daily comfort, even if it costs a bit more.

Choosing according to your personal situation

Your skin type

Your skin type plays a major role in choosing the right formulation. If you’ve got a reactive scalp, prone to redness, itching, or dryness, the foam is almost certainly the better choice. The tolerance studies leave little room for doubt: propylene glycol and alcohol in the liquid solution make these problems worse.

On the other hand, if your skin has no particular sensitivity, the liquid solution may suit you perfectly well and save you money.

Your hair type also significantly influences application. With short or very fine hair, the liquid solution allows for targeted, precise application. You can see exactly where the product goes, control the amount, and it easily reaches the scalp.

With long, thick, or curly hair, though? The foam is far more practical. It spreads better, passes more easily through the hair, and doesn’t drip onto your face or neck.

If you’ve got Afro or kinky hair, the foam offers an additional advantage. These hair types tend to be naturally drier, and the drying effect of alcohol and propylene glycol can weaken them further. The foam respects their structure and natural moisture better.

Practicality

Practicality is a major factor. Liquid solutions generally require two applications daily for best effectiveness. The 5% foam, however, can be used once a day with comparable results, according to studies.

If you’ve got a busy schedule, travel frequently, or know you’ll struggle to remember twice-daily applications, the once-a-day option simplifies things considerably. And over several months, this simplicity can make all the difference to your consistency.

Budget

The budget is worth considering. Liquid solutions are generally less expensive than foam, which can represent a significant difference over a year of treatment.

But be careful with this calculation. If the liquid solution irritates you to the point of stopping treatment after a few weeks, you won’t have saved anything. Worse, you’ll have wasted time and money without results.

A more expensive foam that you actually use regularly for months will give far better results than a cheap solution abandoned halfway through.

When topical minoxidil isn’t enough

Biological limitations

Let’s be honest about the limitations of topical minoxidil, regardless of formulation. Research on follicular sulfotransferase has revealed something important: about a third of patients don’t respond well to minoxidil, and this is linked to low activity of this enzyme in their follicles.

For these people, increasing application frequency or switching formulations (from solution to foam or vice versa) won’t solve the fundamental problem. It’s their biology that limits the conversion of minoxidil to its active form.

The oral alternative

An interesting avenue is emerging from recent studies: patients with low sulfotransferase activity paradoxically respond better to oral minoxidil than topical minoxidil. The explanation lies in metabolism: when taken orally, minoxidil is converted to minoxidil sulphate by the liver, which has much higher sulfotransferase activity than hair follicles. This bypasses the problem of insufficient local conversion.

A clinical trial demonstrated this: after 6 months of treatment, patients receiving 1 mg of oral minoxidil daily showed significantly better results than those using the 5% or 2% topical formulations. The response rate in patients with low follicular enzyme activity reached 85% with oral minoxidil, compared to only 43% with the topical version.

Drug interactions: Certain medications interfere with minoxidil’s effectiveness, and it’s worth knowing about this. Aspirin and salicylates, for example, inhibit sulfotransferase. One study showed that after 14 days of taking low-dose aspirin, only 27% of subjects were predicted to respond to minoxidil, compared to 50% before taking aspirin.

If you regularly take aspirin for cardiovascular reasons, this could explain a disappointing response to treatment. Worth discussing with your GP.

Improving response to minoxidil

On the flip side, topical tretinoin (a vitamin A derivative) can improve the response to minoxidil. Researchers have found that it increases the expression of follicular sulfotransferase. In their study, 43% of patients initially predicted to be non-responders became responders after only 5 days of tretinoin application. This is a strategy that’s beginning to be explored to improve minoxidil results in patients who respond poorly.

What if minoxidil isn’t enough?

Limitations of medical treatment

Minoxidil, whether in foam or solution form, is an excellent medical treatment for slowing hair loss and stimulating regrowth. But let’s be clear about its limitations: it can’t regrow hair where follicles have been dead for a long time. It can’t redraw a completely bald hairline. And it requires continuous application, stop the treatment, and hair loss resumes within 3 to 4 months.

For advanced androgenetic alopecia (stage III and above on the Hamilton-Norwood scale in men, or Ludwig type II-III in women), hair transplantation often becomes the most sensible option. It offers a permanent solution for balding areas, with success rates exceeding 90% when performed under the right conditions.

Modern techniques: Modern techniques have evolved considerably. FUE (Follicular Unit Extraction) allows for the extraction of follicles one by one from the donor area, without a linear scar. The Sapphire FUE variant uses sapphire crystal blades to create the incisions that will receive the grafts, offering even greater precision and density.

DHI (Direct Hair Implantation) goes further by directly implanting the follicles with a Choi implanter pen, without the need for prior incisions.

What truly makes the difference between a successful transplant and a disappointing one? The surgeon’s expertise and the volume of procedures they perform. A surgeon who performs hundreds of procedures annually develops technical mastery and an understanding of aesthetic subtleties that simply can’t be acquired otherwise.

Creating a natural hairline, for example, requires an artistic eye as much as surgical skill. Placing the grafts at the correct angle, direction, and density makes all the difference between a noticeable result and an imperceptible one.

Dr Cinik’s approach

Dr Emrah Cinik combines over 20 years of experience in hair transplant in Turkey with internationally validated scientific protocols. His approach is based on a personalised assessment that takes into account your type of alopecia, the quality of your donor area, your expectations, and your medical history. Because a transplant isn’t a one-size-fits-all solution, it must be tailored to each individual.

The packages offered include the surgical technique (Classic FUE, Sapphire, or DHI, depending on your needs), as well as comprehensive peri-operative support: accommodation in a comfortable hotel, VIP transfers between the airport, hotel, and clinic, complete post-operative care including PRP to improve graft survival, necessary medications, and long-term follow-up. This all-inclusive approach avoids unpleasant surprises and guarantees high-quality, comprehensive care.

For more specific cases, other options are available. No-shave hair transplantation suits professional situations where you can’t afford a visible transformation for several weeks. Beard and eyebrow transplants, or the use of body hair (BHT) when the conventional donor area is insufficient, demonstrate the breadth of modern technical possibilities.

Complementary treatments

Complementary treatments also play a role. PRP (Platelet-Rich Plasma), systematically included in the packages, improves scalp vascularisation and stimulates graft survival. Regenera Activa mesotherapy uses autologous stem cells to regenerate weakened follicles. Low-level laser therapy synchronises the follicles’ entry into the growth phase. These approaches are often combined with transplantation to maximise results.

And what about minoxidil? It still plays a vital role, even after transplantation. Many surgeons recommend it to protect the remaining native hair, the hair that wasn’t transplanted but is at risk of falling out over time. Transplantation restores density to thinning areas, whilst minoxidil preserves what remains. It’s a complementary approach that provides the best long-term results.

The personalised consultation

A personalised consultation allows us to assess your situation precisely. Your alopecia pattern, the quality of your donor area, your age, your medical history, your response to medical treatments if you’ve already tried them, all these elements are important in determining the best treatment plan.

Sometimes, a combination of hair transplantation and minoxidil proves more effective than transplantation alone. Other times, well-managed medical treatment is sufficient to achieve the desired results

Scientific sources

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Buhl, A. E., Waldon, D. J., Baker, C. A., & Johnson, G. A. (1990). Minoxidil sulfate is the active metabolite that stimulates hair follicles. Journal of Investigative Dermatology, 95(5), 553-557. https://doi.org/10.1111/1523-1747.ep12505793

Dooley, T. P., Walker, C. J., Hirshey, S. J., Falany, C. N., & Diani, A. R. (1991). Localization of minoxidil sulfotransferase in rat liver and the outer root sheath of anagen pelage and vibrissa follicles. Journal of Investigative Dermatology, 96(1), 65-70. https://doi.org/10.1111/1523-1747.ep12515856

Friedman, E. S., Friedman, P. M., Cohen, D. E., & Washenik, K. (2002). Allergic contact dermatitis to topical minoxidil solution: Etiology and treatment. Journal of the American Academy of Dermatology, 46(2), 309-312. https://doi.org/10.1067/mjd.2002.119104

Goren, A., Castano, J. A., McCoy, J., Bermudez, F., & Lotti, T. (2015). Novel enzymatic assay predicts minoxidil response in the treatment of androgenetic alopecia. Dermatologic Therapy, 28(4), 252-254. https://doi.org/10.1111/dth.12229

Messenger, A. G., & Rundegren, J. (2004). Minoxidil: mechanisms of action on hair growth. British Journal of Dermatology, 150(2), 186-194. https://doi.org/10.1111/j.1365-2133.2004.05785.x

Olsen, E. A., Whiting, D., Bergfeld, W., Miller, J., Hordinsky, M., Wanser, R., Zhang, P., & Kohut, B. (2007). A multicenter, randomized, placebo-controlled, double-blind clinical trial of a novel formulation of 5% minoxidil topical foam versus placebo in the treatment of androgenetic alopecia in men. Journal of the American Academy of Dermatology, 57(5), 767-774. https://doi.org/10.1016/j.jaad.2007.04.012

Rossi, A., Cantisani, C., Melis, L., Iorio, A., Scali, E., & Calvieri, S. (2012). Minoxidil use in dermatology, side effects and recent patents. Recent Patents on Inflammation & Allergy Drug Discovery, 6(2), 130-136. https://doi.org/10.2174/187221312800166859

Sharma, A., Goren, A., Dhurat, R., Agrawal, S., Sinclair, R., Trüeb, R. M., Vañó-Galván, S., Chen, G., Tan, Y., Kovacevic, M., Situm, M., & McCoy, J. (2019). Tretinoin enhances minoxidil response in androgenetic alopecia patients by upregulating follicular sulfotransferase enzymes. Dermatologic Therapy, 32(3), e12915. https://doi.org/10.1111/dth.12915

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Suchonwanit, P., Thammarucha, S., & Leerunyakul, K. (2019). Minoxidil and its use in hair disorders: a review. Drug Design, Development and Therapy, 13, 2777-2786. https://doi.org/10.2147/DDDT.S214907