Minoxidil explained: how it works, side effects and how long to use it

Key takeaways

• Minoxidil works best on hair that is thinning, not on scalp that has been bald for years.
• Extra shedding in the first two to eight weeks is common and usually a sign the hair cycle is resetting.
• It takes at least four months, and often six to twelve, to judge whether it is working.
• The benefit lasts only while you use it. Most new hair is lost within a few months of stopping.
• Strength, form, and whether to use tablets instead of a lotion are prescription decisions made after a diagnosis.

How does minoxidil work for hair?

Here is a nice bit of medical history. Minoxidil was first developed as a blood pressure tablet. Doctors noticed that patients taking it were growing more hair, and a version for the scalp followed.

Its exact action on the follicle is still not fully understood. What we do know is this. In pattern hair loss, the growing phase of each hair gets shorter with each cycle, and the follicle shrinks. Minoxidil appears to counter this by prolonging the growing phase and helping miniaturised follicles produce longer, thicker hairs. It does not block the hormone DHT, which drives pattern hair loss. That is why I often combine it with other treatments.

Who can use it?

• Men with male pattern hair loss, especially crown thinning and early temple recession.
• Women with female pattern hair loss. The American Academy of Dermatology describes it as the treatment dermatologists most often recommend for women, at 2% or 5% strength.
• Some other hair conditions, as an add-on, at a doctor's discretion.

It is not used during pregnancy or breastfeeding, according to the American Academy of Dermatology. If you have heart disease or low blood pressure, discuss it with a doctor first, even for the lotion.

How do I use topical minoxidil correctly?

Follow your doctor's instructions, but the general principles from MedlinePlus and the American Academy of Dermatology are: - Apply it to a dry scalp, directly on the thinning area, not on the hair. - Use the amount prescribed. More does not speed up growth, and it may increase side effects. - The Mayo Clinic notes it is typically used once daily by women and twice daily by men, depending on the product. - Wash your hands after applying, and keep it away from your eyes and face. - Let it dry before your head touches the pillow, so it does not spread to your forehead and cheeks. - Do not apply it to sunburned, cut or irritated skin.

Solution or foam? The American Academy of Dermatology notes foam may cause less scalp irritation. In Mumbai's humidity, some people find foam less greasy. I suggest what suits your scalp after I have seen it.

Why does my hair fall more when I start minoxidil?

This is the most common reason people stop too early, so it is worth understanding properly.

See, what happens is, minoxidil nudges resting follicles to start a new growing phase. As the new hair starts, it pushes out the old resting hair a little earlier than it would have fallen anyway. The American Academy of Dermatology describes a temporary increase in shedding in the first two to eight weeks, and the Indian Journal of Dermatology, Venereology and Leprology review notes shedding in the first eight weeks is expected and should be explained to patients. So I explain it before you start, not after you panic.

If the shedding continues beyond two to three months, or is very heavy, talk to your doctor rather than stopping on your own.

How long before I see results?

A photo of the same area every month, in the same light and position, is the most honest way to track progress. My article on how long hair treatment takes explains why.

What are the side effects?

Common, usually mild: - Scalp itching, dryness, flaking or burning, which MedlinePlus lists as the most common side effects - Unwanted fine hair on the forehead, cheeks or around the face, especially in women, often from the product spreading - The temporary shedding described above

Less common, see a doctor promptly: - Rapid heartbeat, chest pain or light-headedness - Swelling of the face, hands, ankles or stomach, or sudden weight gain - Trouble breathing, especially when lying down

MedlinePlus also notes it can make skin more sensitive to sunlight.

What about oral minoxidil?

Low-dose oral minoxidil is increasingly used for hair loss, off-label. The Medical Letter, an independent drug review, notes that doses of 0.25 to 2.5 mg daily have been shown to promote regrowth, far lower than blood pressure doses. In one trial in women, 1 mg daily by mouth worked similarly to 5% lotion once daily over 24 weeks, but with more side effects.

The main side effects of oral minoxidil are unwanted hair growth on the face and body, and ankle swelling. Less commonly it can cause a fast heart rate or fluid around the heart. It is not used in pregnancy or breastfeeding.

People ask me, "Doctor, can I just take the tablet? I keep forgetting the lotion." That is a fair reason, and oral minoxidil can be a good option for people who cannot tolerate or keep up with a lotion. But it is a prescription decision. I need to check your blood pressure, heart history and other medicines first. The dose is the skill here. And please, never use blood pressure tablets meant for someone else to treat your hair.

What happens if I stop?

MedlinePlus states that most new hair is lost within a few months of stopping, because minoxidil does not cure pattern hair loss. The American Academy of Dermatology adds that maintained hair may look thinner and shedding gradually increases. If you plan to stop, or to apply it less often, discuss it with your doctor so you can plan a maintenance approach rather than losing your gains suddenly. Stopping is your choice. I just want it to be an informed one.

How we approach this at Dr Tvacha

Minoxidil is one of the most useful tools in hair treatment, but only when it is the right tool for the right diagnosis. At a Rs 499 hair diagnosis at our Thane, Andheri, Bandra or Dahisar centre, my team and I decide whether minoxidil suits you, in which form and strength, and what to combine it with. In the 5-Year Time Machine Hair Plan, home medicines are combined with monthly in-clinic sessions for four months, with a maintenance plan after. See our hair page, or read about oral treatments for male hair loss.

Written by

Dr Amit KarkhanisAesthetic Physician · MBBS, Dip. Dermatology (UK) · Reg. No. 2001/02/1124

Founder of Dr Tvacha, practising in Thane since 2005. Leads the weight loss and hair programmes.