Minoxidil opens potassium channels in vascular smooth muscle, increasing follicular blood flow. Topical 5% solution has been standard for decades; low-dose oral (1.25-5mg) has become popular for hair growth without the topical hassle.
Dose: 1.25-5mg orally daily, or 5% topical solution twice daily.
Caveats: Oral form has more cardiovascular effects (mild fluid retention, hair growth elsewhere). Combine with finasteride for best results. Hair quality of regrowth varies.