Notes
Short, citation-friendly answers to specific hair-loss questions. New note most weekdays. Each one links to the full guide on the same topic.
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FPHL · May 20, 2026
Spironolactone is a common second-line treatment for female pattern hair loss.
Spironolactone is a common second-line treatment for female pattern hair loss. Anti-androgen, oral, prescribed off-label. Not for men. Not safe in pregnancy.
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Mechanism · May 19, 2026
Finasteride does not help telogen effluvium.
Finasteride does not help telogen effluvium. Different mechanism. TE is a synchronised shed after a trigger, not DHT damage. Finasteride only works on DHT-driven loss.
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Mechanism · May 18, 2026
Pattern hair loss is driven by DHT (dihydrotestosterone) shrinking susceptible follicles over years.
Pattern hair loss is driven by DHT (dihydrotestosterone) shrinking susceptible follicles over years. Finasteride and dutasteride work by blocking the enzyme that makes it.
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Oral minoxidil · May 17, 2026
Low-dose oral minoxidil (0.25 to 5 mg/day) is the quiet revolution in hair loss treatment.
Low-dose oral minoxidil (0.25 to 5 mg/day) is the quiet revolution in hair loss treatment. As effective as topical for many people, easier to take, fewer scalp side effects.
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PRP · May 16, 2026
PRP for hair loss has real but modest effects in androgenetic alopecia.
PRP for hair loss has real but modest effects in androgenetic alopecia. Three monthly sessions, then maintenance. Not a substitute for finasteride or minoxidil.
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Microneedling · May 15, 2026
Microneedling adds a real bump to topical minoxidil for AGA.
Microneedling adds a real bump to topical minoxidil for AGA. The data is consistent. The catch: weekly sessions, 1.5mm depth, for at least 12 weeks.
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About · May 14, 2026
What we cover at Regrowth Index: every form of hair loss, the diagnostic flow, the bloods worth requesting, what each treatment actually…
What we cover at Regrowth Index: every form of hair loss, the diagnostic flow, the bloods worth requesting, what each treatment actually does. Every claim cited.
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Urgent · May 13, 2026
See a dermatologist sooner if there's redness, scaling, itching, burning, pain, or visible scarring.
See a dermatologist sooner if there's redness, scaling, itching, burning, pain, or visible scarring. Those suggest a different category.
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Tracking · May 12, 2026
Photographs of the same scalp area, under the same lighting, taken a month apart.
Photographs of the same scalp area, under the same lighting, taken a month apart. Beats counting shed hairs in the drain.
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Hair transplants · May 11, 2026
A hair transplant doesn't grow new hair.
A hair transplant doesn't grow new hair. It moves existing follicles. Realistic density is 30–50 units/cm². Original full hair is 60–100.
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Treatment · May 10, 2026
In 5-year data, finasteride 1mg/day stabilised or improved hair in ~90% of men with AGA.
In 5-year data, finasteride 1mg/day stabilised or improved hair in ~90% of men with AGA. The placebo arm continued progressive loss.
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Bloods · May 9, 2026
Ferritin is the single most useful blood test for hair loss.
Ferritin is the single most useful blood test for hair loss. Hair specialists target above 50 ng/mL; some target 70.
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Evidence · May 8, 2026
Biotin only helps with hair if you're actually deficient, which is rare.
Biotin only helps with hair if you're actually deficient, which is rare. No supplement has been shown to shorten telogen effluvium in well-nourished people.
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Diagnosis · May 7, 2026
Three observations narrow most hair-loss diagnoses: pattern, speed, scalp condition.
Three observations narrow most hair-loss diagnoses: pattern, speed, scalp condition. The combination usually points to one cause.
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Alopecia areata · May 6, 2026
Alopecia areata is autoimmune disease, not a cosmetic problem.
Alopecia areata is autoimmune disease, not a cosmetic problem. ~50% of patchy AA spontaneously regrows within 12 months.
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Diagnosis · May 5, 2026
Pattern hair loss is gradual over years, in specific zones, with progressively thinner shed hairs.
Pattern hair loss is gradual over years, in specific zones, with progressively thinner shed hairs. Telogen effluvium is sudden, diffuse, full-thickness shedding 2–4 months after a trigger.
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Telogen effluvium · May 4, 2026
Post-COVID hair loss is real and almost never permanent.
Post-COVID hair loss is real and almost never permanent. The trigger has already happened. What's needed now is patience.
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Postpartum · May 3, 2026
Postpartum hair loss is common, alarming, and almost always temporary.
Postpartum hair loss is common, alarming, and almost always temporary. Peaks around month 3–4. Resolves by 9–12.
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Minoxidil · May 2, 2026
On topical minoxidil six weeks in and "nothing's happening"?
On topical minoxidil six weeks in and "nothing's happening"? You're on track. Visible change shows at 4–6 months. Full effect at 12.
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Female pattern · May 1, 2026
Is your part widening?
Is your part widening? Female pattern hair loss is diffuse central thinning with the frontal hairline preserved, the "Christmas tree" pattern.