💈 HairBase
🔍▦ Browse all
🌐 EN
Hair guideWhat is the difference between type I and type II 5-alpha-reductase?

What is the difference between type I and type II 5-alpha-reductase?

✓ Medically reviewed✍️ HairBase editorial team📅 Last updated: June 14, 2026⏱ 1 min read
💡 Quick answer

A “stronger DHT block” TikTok is not a diagnosis. Photograph; ask a prescriber about labelled indications.

Type II 5AR is the main story in prostate and many scalp discussions of finasteride 1 mg. Type I is another isoform. Dutasteride’s dual block is why some countries approve it for hair and others keep it off-label. This page will not invent a PMID. Related: dutasteride-versus-finasteride — different URL.

Do not mash leftover 5 mg prostate tablets as a hair stack. Pregnancy pictograms apply. Do not double minoxidil as a 5AR substitute.

A partner who is pregnant and handled crushed tablets should call their clinician. This is not medical advice.

Try the free self-check →
📚 Sources

Sources: StatPearls (NIH) ↗

FAQ

Is dutasteride always better?

This page does not rank. Approvals and AE labels differ.

Can I switch myself?

No. Prescriber.

Same as dutasteride-vs-finasteride?

Related drug compare, different URL. This file is isoform literacy.

More foam on dual block?

No. Follow the carton.

Explore more

Found this helpful? Share it
Not medical advice. General education only; it does not replace diagnosis or treatment by a licensed professional. Figures such as 1 mg or 5% are labelled strengths you may see in your country — not a dosing instruction. 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
Try the free self-check →
Try the free self-check →