Editorial & review policy
How we weight evidence
We rank sources in this order: peer-reviewed systematic reviews and meta-analyses > StatPearls/NIH > clinical bodies (AAD, NHS, Mayo Clinic) > ISHRS transplant standards > FDA/EMA drug labels. Our evidence grades — Proven, Promising, Limited, No evidence — are bound to the underlying data.
Independence and funding
HairBase is funded by advertising and affiliate links, which may earn us a commission at no extra cost to you. This never influences our medical content or evidence grades — no advertiser or affiliate can change a rating, and product mentions are kept separate from clinical guidance.
Review and corrections
A page's last-reviewed date changes only when we genuinely re-check the content against current sources. If you spot an error, tell us and we will correct it promptly; material changes are noted in our updates log. We state uncertainty honestly and avoid overclaiming — where evidence is weak or mixed, we say so.
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⚠️ 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