How it works
Dutasteride is a dual inhibitor of the enzyme 5α-reductase, blocking both type I and type II isoenzymes. Finasteride, by comparison, inhibits only type II. Type I 5α-reductase is found predominantly in sebaceous glands and the skin, while type II is the dominant form in the dermal papilla of hair follicles and in the prostate. By inhibiting both isoenzymes, dutasteride reduces serum dihydrotestosterone (DHT) more completely than finasteride, which inhibits only the type II isoenzyme. DHT binds to androgen receptors in the dermal papilla with higher affinity than testosterone and drives the miniaturisation of genetically susceptible hair follicles — the hallmark of androgenetic alopecia. Blocking DHT production at the follicular level slows and may partially reverse this miniaturisation cycle. The rationale for topical application is to deliver dutasteride directly to the follicle while limiting systemic absorption. Because dutasteride has a relatively large molecular weight and high lipophilicity, penetration across the stratum corneum is limited; specialised vehicles (liposomal gels or alcohol-based solutions) are used to improve follicle-directed delivery while keeping serum exposure low. Even so, topical application does not eliminate systemic absorption entirely, and some DHT suppression can occur — which is why the prescriber monitors for sexual, breast, fertility and mood effects. Pregnant people and those who could become pregnant must avoid any contact with the spray, because dutasteride inhibits fetal 5α-reductase and can disrupt normal development of male external genitalia. Capsules of oral dutasteride are known to be absorbed through the skin, and the same precaution principle applies to the compounded liquid.How to use
Applying the spray is a short procedure, and the order matters — measure first, then apply, then let it dry before anything touches it.1
Use the pharmacy-labelled dose
Apply exactly as labelled by the dispensing pharmacy — the number of pumps and frequency are specific to that compounded formula.
2
Apply to scalp and let it dry
Apply to a dry, intact scalp, wash hands afterwards, and prevent transfer to other people or surfaces until fully dry. Do not use extra product after a missed application, and do not combine with oral dutasteride unless specifically prescribed.
Dose schedule
- Daily, as labelled — consistency matters more than any single application.
- Review after several months — the prescriber assesses scalp tolerance, systemic symptoms, adherence and standardised photographs, and continues the off-label compounded treatment only while it is considered suitable.
What has been reported
Contact your doctor if
- Chest pain, fainting, breathing difficulty, facial swelling, or a widespread rash
- A breast lump, severe mood change, persistent sexual symptoms, palpitations, or ankle swelling
- Wet product contacts a pregnant person, someone who could become pregnant, a child, or a pet
Storage
Keep in the original pharmacy-labelled bottle, tightly closed, upright, and away from heat or flame. Follow the pharmacy’s storage and use-by instructions exactly.What to expect
Hair treatment is gradual. Early shedding can occur, and photographs taken in the same light are more useful than day-to-day checking. The doctor normally reviews tolerance and progress after several months, and continues the treatment only while the balance of benefit and risk remains appropriate.Related reading
- Finasteride — how it works and evidence
- Minoxidil — topical vs oral
- Androgenetic alopecia
- Safety and eligibility
Start a consultation
Hair-growth consultation
Answer the hair-growth questionnaire and a registered doctor reviews it.
They decide whether treatment is appropriate, which one, and at what dose —
and declining is a normal outcome. See what it costs
and how the review works.