A substance that widens blood vessels. Minoxidil was first a blood-pressure vasodilator, and improved scalp blood flow was an early theory for how it grows hair — though its main action is now thought to be opening potassium channels and prolonging the growth phase, not blood flow alone.
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Not medical advice. General education only; it does not replace diagnosis or treatment by a licensed professional. Consult a board-certified dermatologist before starting, stopping or changing any treatment.
⚠️ When to see a doctor — don’t self-treat
- Sudden patchy or circular bald spots
- Redness, scaling, pus, pain or itch (possible scarring alopecia — treat urgently)
- Broken hairs or rapid loss
- Loss with body-wide signs (weight loss, fatigue, cycle changes, acne, extra hair)
- Loss right after a new medication
- Any hair loss in a child