Topical minoxidil: when to judge whether it works

Two months of minoxidil solution, twice a day. You lean towards the mirror, push your parting aside and compare it with how you remember your scalp at the start of the year. Nothing worse, nothing better. So, is it working or not?

At two months, nobody can tell. Not you, not your mirror. Minoxidil works slowly, and official sources give fairly precise timelines for when to ask the question.

The timelines, source by source

The leaflets of solutions sold in France give the shortest timeline. The 5% leaflet says 2 months of treatment may be needed before hair growth is stimulated⁶. The 2% leaflet says about 3 to 4 months, and its summary of product characteristics specifies about 4 months or more, varying from person to person⁵. The French Society of Dermatology gives the same range: effectiveness can usually only be judged after 3 to 4 months of regular use, sometimes longer².

Dermatologists still ask you to wait longer before drawing conclusions. The European S3 guideline sets the assessment at least 6 months after starting¹. The British Association of Dermatologists says at least 6 months, possibly 12, before any benefit shows⁴. And the American Academy of Dermatology: it usually takes about 6 to 12 months to see results³.

The two sets of figures don’t contradict each other. The 3 to 4 months is when an effect may begin; the 6 to 12 months is when you can reasonably decide.

Why it takes so long

Minoxidil doesn’t grow a hair in a few days. It works on the cycle: it restarts resting follicles and, according to the S3 guideline, turns some of the hairs thinned by androgenetic alopecia back into normal hairs¹. That change follows the pace of the hair cycle, which is measured in months.

The start muddies the picture too. In the first 8 weeks, heavier shedding is possible: follicles restarted at the same time let go of their old hair¹. We explain it in detail in the minoxidil shed in the first weeks. Judging during this phase means judging at the worst possible moment.

Finally, the first hairs to grow back are almost invisible. According to the leaflet, they’re soft, downy and hard to see, then they can thicken if treatment continues⁵. So it takes time before they show up in a photo.

What the studies show

One trial is often used as a reference. Olsen and colleagues followed 393 men aged 18 to 49, randomly assigned to apply a 5% solution, a 2% solution or a placebo twice a day for 48 weeks⁷. By the end, the 5% solution had produced 45% more regrowth than the 2% one, and the response had appeared earlier. The trade-off: more itching and irritation with 5%⁷. Limits to bear in mind: only young men took part, and the study summary doesn’t say in which week the difference appeared.

In women, a 48-week trial reported in the S3 guideline compared the same strengths. At 12 months, the count of non-vellus (non-downy) hairs had risen by 13.8% with the 2% solution, 17.3% with 5% and 6.8% with placebo; the difference between 2% and 5% wasn’t significant¹. In France, only the 2% solution is licensed for women⁵⁶.

These averages hide very different responses from one person to the next. The French Society of Dermatology sums them up in three equal shares²:

The AAD makes the same point: minoxidil can help early hair loss, but it can’t regrow an entire head of hair³.

How to judge it in practice

The trap is waiting for dramatic regrowth. For a third of people, the result is hair loss that stops². And hair loss that no longer progresses doesn’t show in the mirror: nothing changes, and that’s exactly the result.

The only way to see it is to compare against a fixed starting point. Before your first application, take a set of photos of the areas you’re treating: crown, parting, temples. Then compare at 6 months and at 12 months, in the same conditions. Look at three things:

• how much scalp shows through the hair, on the crown and along the parting;
• how wide the parting is, always at the same spot;
• the fine little hairs at the temples or crown, and whether they get longer and darker.

If nothing has moved at 6 months when your hair loss was progressing before, that isn’t necessarily a failure: it may be stabilisation. If the area has thinned despite regular use, it’s time to talk it over. Either way, talk to your pharmacist or doctor before changing anything, and bring your photos. If you’re unsure about the form of the product, our article on minoxidil foam or solution compares the two.

Other options are judged the same way, on the same timescale: the trial comparing rosemary oil with minoxidil was measured on standardised photos at 3 and 6 months.

What if you stop?

Minoxidil only works while you use it. The French Society of Dermatology describes it as a suspensive treatment: once stopped, hair loss gradually resumes its natural course². The S3 guideline adds that the increased shedding usually starts 3 months after stopping¹, and the leaflet expects a return to your starting point within 3 to 4 months⁵.

The AAD describes what you then notice: some hairs look and feel thinner, and you gradually shed more³. The benefit gained over the months of treatment fades. That’s another reason to judge at 6 months, on photos, rather than give up at 2 months on a hunch.

Stopping or continuing is a decision to make with your pharmacist or doctor. If your hair loss may have a cause other than genetics, the causes of hair loss in women and inherited hair loss can help you see more clearly.

The real test: your day-one photo

From one month to the next, the change is too slow to see. Between your first photo and the one at six months, it becomes readable, as long as both are taken the same way: same light, same angle, same distance, hair dry and styled the same.

That’s what Calvap does. One photo a week, zone by zone, guided by a ghost of the previous one so you find the same framing. On the six-month mark, you drag the slider between week 1 and week 24 and see what has changed. Your treatment is logged in the journal, on the same timeline. Your photos stay on your phone, and you can show them to your doctor.