Twice-weekly (or three-times-weekly) dutasteride dosing has been proposed as an alternative to daily dosing, using the drug’s long terminal half-life of about 5 weeks to hold DHT suppression with potentially fewer side effects. One randomized, investigator-blinded pilot trial in 60 men has now tested the intermittent regimens against daily finasteride; no large trial has. Hair loss dosing of dutasteride is off-label, since the FDA approves the drug for bph/">benign prostatic hyperplasia only.
Pharmacokinetic Rationale
Dutasteride’s half-life of approximately 5 weeks means that even with non-daily dosing, serum levels remain therapeutic. After reaching steady state (which takes months), missing individual doses has minimal impact on serum DHT suppression due to the drug’s extensive tissue binding and slow clearance.
Common Protocols
- Twice weekly: 0.5 mg on Monday and Thursday (or any two days separated by 3-4 days)
- Three times weekly: 0.5 mg on Monday, Wednesday, Friday
- Alternate days: 0.5 mg every other day
All protocols use the standard 0.5 mg capsule. Clinical guide.
What the Pilot Trial Found
Sereepanpanich and colleagues randomised 60 men aged 21 to 60 to dutasteride 0.5 mg twice weekly, dutasteride 0.5 mg thrice weekly, or finasteride 1 mg daily for 24 weeks. Mean change in terminal hair count was 7.74 hairs/cm² on twice-weekly dutasteride, 17.43 on thrice-weekly, and 12.81 on daily finasteride. Thrice-weekly dosing beat twice-weekly on hair density and diameter, but did not significantly beat daily finasteride on hair count. Sexual adverse events were similar across the three groups. Participants were not blinded to their allocation, and 60 men is a pilot.
Sources
- Sereepanpanich V, Khunkhet S, Rojhirunsakool S, Udompataikul M. Efficacy and safety of twice- or thrice-weekly dutasteride versus daily finasteride in men with androgenetic alopecia: a randomized, investigator-blinded, active-controlled, parallel-group pilot study. JAAD Int. 2025;23:69-76. PubMed 41140354
- FDA. Avodart (dutasteride) Prescribing Information, Section 12.3 Pharmacokinetics. NDA 021319.